Question:

What is a spinal drip?

Answer:

Spontaneous Cerebrospinal Fluid Leak Syndrome (SCSFLS) is a medical condition in which the cerebrospinal fluid (CSF) held in and around a human brain and spinal cord leaks out of the surrounding protective sac, the dura, for no apparent reason.

More Info:

Cerebrospinal fluid (CSF) is a clear colorless bodily fluid produced in the choroid plexus of the brain. It acts as a cushion or buffer for the cortex, providing a basic mechanical and immunological protection to the brain inside the skull and serves a vital function in cerebral autoregulation of cerebral blood flow. The CSF occupies the subarachnoid space (the space between the arachnoid mater and the pia mater) and the ventricular system around and inside the brain and spinal cord. It constitutes the content of the ventricles, cisterns, and sulci of the brain, as well as the central canal of the spinal cord. CSF serves four primary purposes: Various comments by ancient physicians have been read as referring to CSF. Hippocrates discussed "water" surrounding the brain when describing congenital hydrocephalus, and Galen referred to "excremental liquid" in the ventricles of the brain, which he believed was purged into the nose. But for some 16 intervening centuries of ongoing anatomical study, CSF remains unmentioned in the literature. This is perhaps because of the prevailing autopsy technique, which involved cutting off the head, thereby removing evidence of the CSF before the brain was examined. The modern rediscovery of CSF is now credited to Emanuel Swedenborg. In a manuscript written between 1741 and 1744, unpublished in his lifetime, Swedenborg referred to CSF as "spirituous lymph" secreted from the roof of the fourth ventricle down to the medulla oblongata and spinal cord. This manuscript was eventually published in translation in 1887. Albrecht von Haller, a Swiss physician and physiologist made note in his 1747 book on physiology that the "water" in the brain was secreted into the ventricles and absorbed in the veins, and when secreted in excess, could lead to hydrocephalus. Francois Magendie studied the properties of CSF by vivisection. He discovered the foramen Magendie, the opening in the roof of the fourth ventricle, but mistakenly believed that CSF was secreted by the pia mater. Thomas Willis (noted as the discoverer of the circle of Willis) made note of the fact that the consistency of the CSF is altered in meningitis. In 1891, W. Essex Wynter began treating tubercular meningitis by tapping the subarachnoid space, and Heinrich Quincke began to popularize lumbar puncture, which he advocated for both diagnostic and therapeutic purposes. In 19th and early 20th century literature, particularly German medical literature, liquor cerebrospinalis was a term used to refer to CSF. In 1912, William Mestrezat gave the first accurate description of the chemical composition of the CSF. In 1914, Harvey W. Cushing published conclusive evidence that the CSF is secreted by the choroid plexus. CSF is produced in the brain by modified ependymal cells in the choroid plexus (approx. 50-70%) and the remainder is formed around blood vessels and along ventricular walls. It circulates from the lateral ventricles to the foramina of Monro (Interventricular foramina), third ventricle, aqueduct of Sylvius (Cerebral aqueduct), fourth ventricle, foramen of Magendie (Median aperture) and foramina of Luschka (Lateral apertures), subarachnoid space over brain and spinal cord. It should be noted that the CSF moves in a pulsatile manner throughout the CSF system with nearly zero net flow. CSF is reabsorbed into venous sinus blood via arachnoid granulations. It had been thought that CSF returns to the vascular system by entering the dural venous sinuses via the arachnoid granulations (or villi). However, some have suggested that CSF flow along the cranial nerves and spinal nerve roots allow it into the lymphatic channels; this flow may play a substantial role in CSF reabsorbtion, in particular in the neonate, in which arachnoid granulations are sparsely distributed. The flow of CSF to the nasal submucosal lymphatic channels through the cribriform plate seems to be especially important. The CSF contains approximately 0.3% plasma proteins, or approximately 15 to 40 mg/dL, depending on sampling site, and it is produced at a rate of 500 ml/day. Since the subarachnoid space around the brain and spinal cord can contain only 135 to 150 ml, large amounts are drained primarily into the blood through arachnoid granulations in the superior sagittal sinus. Thus the CSF turns over about 3.7 times a day. This continuous flow into the venous system dilutes the concentration of larger, lipid-insoluble molecules penetrating the brain and CSF. CSF pressure, as measured by lumbar puncture (LP), is 10-18 O2cmH (8-15 mmHg or 1.1-2 kPa) with the patient lying on the side and 20-30cmH2O (16-24 mmHg or 2.1-3.2 kPa) with the patient sitting up. In newborns, CSF pressure ranges from 8 to 10 O2cmH (4.4–7.3 mmHg or 0.78–0.98 kPa). Most variations are due to coughing or internal compression of jugular veins in the neck. When lying down, the cerebrospinal fluid as estimated by lumbar puncture is similar to the intracranial pressure. There are quantitative differences in the distributions of a number of proteins in the CSF. In general, globular proteins and albumin are in lower concentration in ventricular CSF compared to lumbar or cisternal fluid. The IgG index of cerebrospinal fluid is a measure of the immunoglobulin G content, and is elevated in multiple sclerosis. It is defined as IgG index = (IgGCSF / IgGserum ) / (albuminCSF / albuminserum). A cutoff value has been suggested to be 0.73, with a higher value indicating presence of multiple sclerosis.
When CSF pressure is elevated, cerebral blood flow may be constricted. When disorders of CSF flow occur, they may therefore affect not only CSF movement but also craniospinal compliance and the intracranial blood flow, with subsequent neuronal and glial vulnerabilities. The venous system is also important in this equation. Infants and patients shunted as small children may have particularly unexpected relationships between pressure and ventricular size, possibly due in part to venous pressure dynamics. This may have significant treatment implications, but the underlying pathophysiology needs to be further explored. CSF connections with the lymphatic system have been demonstrated in several mammalian systems. Preliminary data suggest that these CSF-lymph connections form around the time that the CSF secretory capacity of the choroid plexus is developing (in utero). There may be some relationship between CSF disorders, including hydrocephalus and impaired CSF lymphatic transport. CSF can be tested for the diagnosis of a variety of neurological diseases. It is usually obtained by a procedure called lumbar puncture. Removal of CSF during lumbar puncture can cause a severe headache after the fluid is removed, because the brain hangs on the vessels and nerve roots, and traction on them stimulates pain fibers. This pain can be relieved by intrathecal injection of sterile isotonic saline. Lumbar puncture is performed in an attempt to count the cells in the fluid and to detect the levels of protein and glucose. These parameters alone may be extremely beneficial in the diagnosis of subarachnoid hemorrhage and central nervous system infections (such as meningitis). Moreover, a CSF culture examination may yield the microorganism that has caused the infection. By using more sophisticated methods, such as the detection of the oligoclonal bands, an ongoing inflammatory condition (for example, multiple sclerosis) can be recognized. A beta-2 transferrin assay is highly specific and sensitive for the detection for, e.g., CSF leakage.
Lumbar puncture can also be performed to measure the intracranial pressure, which might be increased in certain types of hydrocephalus. However a lumbar puncture should never be performed if increased intracranial pressure is suspected because it can lead to brain herniation and ultimately death. This fluid has an importance in anesthesiology. Baricity refers to the density of a substance compared to the density of human cerebrospinal fluid. Baricity is used in anesthesia to determine the manner in which a particular drug will spread in the intrathecal space. A 2010 study showed analysis of CSF for three protein biomarkers can indicate the presence of Alzheimer's disease. The three biomarkers are CSF amyloid beta 1-42, total CSF tau protein and P-Tau181P. In the study, the biomarker test showed good sensitivity, identifying 90% of persons with Alzheimer's disease, but poor specificity, as 36% of control subjects were positive for the biomarkers. The researchers suggested the low specificity may be explained by developing but not yet symptomatic disease in controls. Arachnoid granulation  Arachnoid trabeculae
Denticulate ligaments
M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
Spontaneous cerebrospinal fluid leak syndrome (SCSFLS) is a medical condition in which the cerebrospinal fluid (CSF) held in and around a human brain and spinal cord leaks out of the surrounding protective sac, the dura, for no apparent reason. The dura, a tough, inflexible tissue, is the outermost of the three layers of the meninges, the system of meninges surrounding the brain and spinal cord. (The other two meningeal layers are the pia mater and the arachnoid mater). A spontaneous cerebrospinal fluid leak is one of several types of cerebrospinal fluid leaks and occurs due to the presence of one or more holes in the dura. A spontaneous CSF leak, as opposed to traumatically caused CSF leaks, arises idiopathically. A loss of CSF greater than its rate of production leads to a decreased volume inside the skull known as intracranial hypotension. A CSF leak is most often characterized by a severe and disabling headache and a spectrum of various symptoms which occur as a result of intracerebral hemorrhage (ICH). These symptoms can include: dizziness, nausea, fatigue, a metallic taste in the mouth (indicative of a cranial leak), myoclonus, tinnitus, tingling in the limbs, and facial weakness amongst others. A CT scan can identify the site of a cerebrospinal fluid leakage. Once identified, the leak can often be repaired by an epidural blood patch, an injection of the patient's own blood at the site of the leak, fibrin glue injection or surgery. SCSFLS afflicts 5 out of every 100,000 people. On average, the condition is developed at the age of 42, and women are twice as likely as men to develop the condition. Some people with SCSFLS chronically leak cerebrospinal fluid despite repeated attempts at patching, leading to long-term disability due to pain and nerve damage. SCSFLS was first described by German neurologist Georg Schaltenbrand in 1938 and by American physician Henry Woltman of the Mayo Clinic in the 1950s. SCSFLS is classified into two main types, cranial leaks and spinal leaks. Cranial leaks occur in the head. In some cases, CSF can be seen dripping out of the nose, or ear. Spinal leaks occur when one or more holes form in the dura along the spinal cord. Both cranial and spinal spontaneous CSF leaks cause neurological symptoms as well as spontaneous intracranial hypotension, diminished volume and pressure of the cranium. While referred to as intracranial hypotension the intracranial pressure may be normal, but low-volume CSF is instead the underlying issue. For this reason SCSFLS is referred to as CSF hypovolemia as opposed to CSF hypotension. Most people who develop SCSFLS feel a sudden onset of a severe and acute headache. It is a headache usually but not necessarily orthostatic in nature, typically becoming prominent throughout the day, in which usually the pain is worse when the person is vertical and less severe when horizontal. Other symptoms include dizziness and vertigo, facial numbness or weakness, unusually blurry or double vision, neuralgia, fatigue, a metallic taste in the mouth, nausea, or vomiting. Leaking CSF can sometimes be felt or observed as discharge through the nose or ear. Orthostatic headaches can be incapacitating; these ailments often become chronic and can be sufficiently disabling to make those afflicted unable to work. Some patients with CSF leak will develop headaches that begin in the afternoon. This is known as second-half-of-the-day headache. This may be an initial presentation of CSF leak or appear after treatment and likely indicates a slow CSF leak. Lack of CSF pressure and volume allows the brain to descend through the foramen magnum, or occipital bone, the large opening at the base of the skull. The lower portion of the brain is believed to stretch or impact one or more cranial nerve complexes, thereby causing a variety of sensory symptoms. Nerves that can be affected and their related symptoms are detailed in the table at right. The two main theories as to the underlying cause of SCSFLS are as a result of a connective tissue disorder or spinal drainage problems. A spontaneous CSF leak is idiopathic; it can arise spontaneously or from an unknown cause. Various scientists and physicians have suggested that this condition may be the result of an underlying connective tissue disorder affecting the spinal dura. It may also run in families and be associated with aortic aneurysms and joint hypermobility. Up to two thirds of those afflicted demonstrate some type of generalized connective tissue disorder. Marfan syndrome, Ehlers-Danlos syndrome and autosomal dominant polycystic kidney disease are the three most common connective tissue disorders associated with SCSFLS. Roughly 20% of patients with SCSFLS exhibit features of Marfan syndrome, including tall stature, chest divot (pectus excavatum), joint hypermobility and arched palate. However these patients do not exhibit any other Marfan syndrome presentations. Some other studies have proposed that issues with the spinal venous drainage system may cause a CSF leak. According to this theory, dural holes and intracranial hypotension are symptoms caused by low pressure in the epidural space due to outflow to the heart through the inferior vena cava vein. Patients with a nude (absent) nerve root are at increased risk for developing recurrent CSF leaks. Cranial CSF leaks are as a result of intracranial hypertension in a vast majority of cases. The increased pressure causes a rupture of the cranial dura mater, leading to CSF leak and intracranial hypotension. Lumbar disc herniation has been reported to cause CSF leak in at least one case. Degenerative spinal disc diseases cause a disc to pierce the dura mater, leading to a CSF leak. Another view of the cause of orthostatic headaches proposes a malformed distribution of craniospinal elasticity as a result of the collapse of the lower spine's CSF space resulting in the collapse of the dura sac. Cerebrospinal fluid is produced by the choroid plexus in the brain and contained by the dura and arachnoid layers of the meninges. The brain floats in CSF, which also transports nutrients to the brain and spinal cord. As holes form in the spinal dura mater, CSF leaks out into the surrounding space. The CSF is then absorbed into the spinal epidural venous plexus or soft tissues around the spine. Due to the sterile conditions of the soft tissues around the spine there is no risk of meningitis. The primary place of first complaint to a physician is a hospital emergency room. Up to 94% of those suffering from SCSFLS are initially misdiagnosed. Incorrect diagnoses include migraines, meningitis, and psychiatric disorders. The average time from onset of symptoms until definitive diagnosis is 13 months. A study found a 0% success rate for proper diagnosis in the emergency department. Diagnosis of CSF leak can be done through various imaging techniques, chemical tests of bodily fluid discharged from a head orifice, or clinical exam. The use of CT, MRI, and assays are the most common types of CSF leak instrumental tests. Many CSF leaks are occult and do not show up on imaging and chemical assays, thus such diagnostic tools are not definitive to rule out CSF leaks. A clinician may often depend upon patient history and exam to diagnose, for example: discharge of excessive amount of clear fluid from the nose upon bending over, the increase in headache following a Valsalva maneuver or the reduction of headache when the patient takes a prone position are positive indicators. As most candidates for CSF leak do not have access to imaging and laboratory tools (modern medicine), clinical exam is the most often used means to diagnose CSF leaks. Improved patient response to conservative treatment may further define a positive diagnosis. The lack of clinician awareness of the signs -symptoms and ailments- of a CSF leak is the greatest challenge to proper diagnosis and treatment, in particular: the loss of the orthostatic characteristic of headache and that every chronic CSF leaker will have a unique symptom set which as a whole contributes to the underlying condition, and diagnosis of, a CSF leak. Diagnosis of a cerebrospinal fluid leak is performed through a combination of measurement of the CSF pressure and a computed tomography myelogram (CTM) scan of the spinal column for fluid leaks. The opening fluid pressure in the spinal canal is obtained by performing a lumbar puncture, also known as a spinal tap. Once the pressure is measured, radiopaque contrast material is injected into the spinal fluid. The contrast then diffuses out through the dura sac before leaking through dural holes. This allows for a CTM with fluoroscopy to locate and image any sites of dura rupture via contrast seen outside the dura sac in the imagery. Magnetic resonance imaging is historically less effective at directly imaging sites of CSF leak. MRI studies may show pachymeningeal enhancement (when the dura mater looks thick and inflamed) and an Arnold-Chiari malformation in many, but not all, cases. An Arnold-Chiari malformation occurs when the brain sags and has a downward displacement due to the decreased volume and buoyancy of cerebrospinal fluid in which the brain floats. MRIs can present as completely normal, however, and are not the study of choice. An alternate method of locating the site of a CSF leak is to use heavily T2-weighted MR myelography. This has been effective in identifying the sites of a CSF leak without the need for a CT scan, lumbar puncture, and contrast and at locating fluid collections such as CSF pooling. MRIs done on patients sitting upright demonstrated no difference in MRI results compared to those lying down. The use of intrathecal contrast and MR Myelography is also an alternative method of locating CSF leaks with a very high degree of success. When cranial CSF leak is suspected because of discharge from the nose or ear that is potentially CSF, the fluid can be collected and tested with a beta-2 transferrin assay. This test can positively identify if the fluid is cerebrospinal fluid. Patients with CSF leak have been noted to have very low or even negative opening pressures. However, patients with confirmed CSF leaks may also demonstrate completely normal opening pressures. In 18–46% of cases, the CSF pressure is measured within the normal range. Analysis of spinal fluid may demonstrate lymphocytic pleocytosis and elevated protein content or xanthochromia. This is hypothesized to be due to increased permeability of dilated meningeal blood vessels and a decrease of CSF flow in the lumbar subarachnoid space. The diagnostic criteria for SCSFLS is based on the 2004 International Classification of Headache Disorders, 2nd edn (ICHD-II) (Table 1) (50) criteria. However, the presentation of patients with confirmed diagnosis may be very different from that of the clinical diagnostic criteria and cannot be considered authoritative. The treatment of choice for this condition is the surgical application of epidural blood patches, which has a 90% success rate in treating dural holes; a rate higher than that of a conservative treatment of bed rest and hydration. Through the injection of a person's own blood into the area of the hole in the dura, an epidural blood patch uses blood's clotting factors to clot the sites of holes. The volume of autologous blood and number of patch attempts for patients is highly variable. One quarter to one third of SCSFLS patients do not have relief of symptoms from epidural blood patching. If blood patches alone do not succeed in closing the dural tears, placement of percutaneous fibrin glue can be used in place of blood patching, raising the effectiveness of forming a clot and arresting CSF leakage. In extreme cases of intractable CSF leak, a surgical lumbar drain has been used. This procedure is believed to decrease spinal CSF volume while increasing intracranial CSF pressure and volume. This procedure restores normal intracranial CSF volume and pressure while promoting the healing of dural tears by lowering the pressure and volume in the dura. This procedure has led to positive results leading to relief of symptoms for up to one year. For patients who do not respond to either epidural blood patching or fibrin glue, neurosurgery is available to directly repair leaking meningeal diverticula. The areas of dura leak can be tied together in a process called ligation and then a metal clip can be placed in order to hold the ligation closed. Alternatively, a small compress called a muscle pledget can be placed over the dura leak and then sealed with gel foam and fibrin glue. Primary suturing is rarely able to repair a CSF leak and in some patients exploration of the dura may be required to properly locate all sites of CSF leak. The use of an abdominal binder has also been employed as a treatment. Final outcomes for people with SCSFLS remain poorly studied. Some of those afflicted continue to leak CSF from one or more sites and may suffer from unremitting symptoms for many years. People with chronic SCSFLS may be disabled and unable to work. Recurrent CSF leak at an alternate site after recent repair is common. Several complications can occur as a result of SCSFLS including decreased cranial pressure, brain herniation, infection, blood pressure problems, transient paralysis, and coma.The primary and most serious complication of SCSFLS is spontaneous intracranial hypotension, where pressure in the brain is severely decreased. This complication leads to the hallmark symptom of severe orthostatic headaches. People with cranial CSF leaks have a higher chance of developing meningitis than those with spinal CSF leaks. Additionally, if cranial leaks last more than seven days, the chances of developing meningitis are significantly higher. Spinal CSF leaks do not usually result in meningitis due to the mostly aseptic conditions of the spinal dura. When a CSF leak occurs at the temporal bone surgery becomes necessary in order to prevent infection and repair the leak. Orthostatic hypotension is another complication which occurs due to autonomic dysfunction when blood pressure drops significantly. The autonomic dysfunction is caused by compression of the brain stem, which controls breathing and circulation. An Arnold-Chiari malformation is a downward displacement of lower parts of the brain through the skull opening that occurs due to a lack of CSF volume and pressure. A further, albeit rare, complication of CSF leak is transient quadriplegia due to a sudden and significant loss of CSF. This loss results in hindbrain herniation and causes major compression of the upper cervical spinal cord. The quadriplegia dissipates once the patient lays supine. An extremely rare complication of SCSFLS is third nerve palsy, where the ability to move one's eyes becomes difficult and interrupted due to compression of the third cranial nerve. Although other sources consider 3rd nerve palsy a common manifestation of CSF leaks. There are documented cases of reversible frontotemporal dementia and coma. Coma due to a CSF leak has been successfully treated by using blood patches and/or fibrin glue and placing the patient in the Trendelenburg position. Empty sella syndrome, a boney structure that surround the pituitary gland, occurs in CSF leak patients. A 1994 community-based study indicated that two out of every 100,000 people suffered from SCSFLS, while a 2004 emergency room-based study indicated five per 100,000. SCSFLS generally affects the young and middle aged; the average age for onset is 42.3 years, but onset can range from ages 22 to 61. In an 11-year study women were found to be twice as likely to be affected as men. Studies have shown that SCSFLS runs in families and it is suspected that genetic similarity in families includes weakness in the dura mater, which leads to SCSFLS. Large scale population-based studies have not yet been conducted. While a majority of SCSFLS cases continue to be undiagnosed or misdiagnosed, an actual increase in occurrence is unlikely. Spontaneous CSF leaks have been described by notable physicians and reported in medical journals dating back to the early 1900s. German neurologist Georg Schaltenbrand reported in 1938 and 1953 what he termed "aliquorrhea", a condition marked by very low, unobtainable, or even negative CSF pressures. The symptoms included orthostatic headaches and other features that are now recognized as spontaneous intracranial hypotension. A few decades earlier, the same syndrome had been described in French literature as "hypotension of spinal fluid" and "ventricular collapse". In 1940, Henry Woltman of the Mayo Clinic wrote about "headaches associated with decreased intracranial pressure". The full clinical manifestations of intracranial hypotension and CSF leaks were described in several publications reported between the 1960s and early 1990s. Modern reports of spontaneous CSF leak have been reported to medical journals since the late 1980s. IV Cosyntropin, a corticosteroid that causes the brain to produce additional spinal fluid to replace the volume of the lost CSF and alleviate symptoms, has been used to treat CSF leaks. In two small studies of two patients and another with one patient who suffered from recurrent CSF leaks where repeated blood patches failed to form clots and relieve symptoms, the patients received temporary but complete resolution of symptoms with an epidural saline infusion. The saline infusion temporarily restores the volume necessary for a patient to avoid SIH until the leak can be repaired properly. Intrathecal saline infusion is used in urgent cases such as intractable pain or decreased consciousness. The gene TGFBR2 has been implicated in several connective tissue disorders including Marfan syndrome, arterial tortuosity and thoracic aortic aneurysm. A study of patients with SCSFLS demonstrated no mutations in this gene. Minor features of Marfan syndrome has been found in 20% of CSF leak patients. Abnormal findings of fibrillin-1 has been documented in these CSF leak patients but only one patient demonstrated a fibrillin-1 defect consistent with Marfan syndrome.
The arachnoid mater is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is interposed between the two other meninges, the more superficial and much thicker dura mater and the deeper pia mater, from which it is separated by the subarachnoid space. The delicate arachnoid layer is attached to the inside of the dura and surrounds the brain and spinal cord. It does not line the brain down into its sulci (folds), as does the pia mater, with the exception of the longitudinal fissure, which divides the left and right cerebral hemispheres. Cerebrospinal fluid (CSF) flows under the arachnoid in the subarachnoid space. The arachnoid mater makes arachnoid villi, small protrusions through the dura mater into the venous sinuses of the brain, which allow CSF to exit the subarachnoid space and enter the blood stream. The arachnoid mater and dura mater are very close together throughout the cranium all the way to S2, where the two layers fuse into one layer and terminate. Sandwiched between the dura and arachnoid maters lie some veins that connect the brain's venous system with the venous system in the dura mater. The arachnoid mater is named after the Greek words "Arachne" ("spider") and suffix "-oid" ("in the image of"), and "mater" (the Latin word for mother), because of the fine spider web-like appearance of the delicate fibres of the arachnoid which extend down through the subarachnoid space and attach to the pia mater. The arachnoid mater covering the brain is referred to as the "arachnoidea encephali," and the portion covering the spinal cord as the "arachnoidea spinalis." The arachnoid and pia mater are sometimes considered as a single structure, the leptomeninx, or the plural version, leptomeninges. ("Lepto"- from the Greek root meaning "thin"). Similarly, the dura in this situation is called the pachymeninx. CSF circulates in the subarachnoid space (between arachnoid and pia mater). Cerebrospinal fluid is produced by the choroid plexus (inside the ventricles of the brain, which are in direct communication with the subarachnoid space so the CSF can flow freely through the nervous system). Cerebrospinal fluid is a transparent, colourless fluid and it is produced at about 500 ml/day. Its electrolyte levels, glucose levels, and pH are very similar to those in plasma, but the presence of blood in cerebrospinal fluid is always abnormal. There are some minor differences among the meninges. The dura mater, the outermost part, is a loosely arranged, fibroelastic layer of cells, characterized by multiple interdigitating cell processes, no extracellular collagen, and significant extracellular spaces. The middle region is a mostly fibrous portion. The arachnoid is composed of an outermost portion (arachnoid barrier cell layer) with tightly packed cells and no extracellular collagen; that is why it is considered to represent an effective morphological and physiological meningeal barrier between the cerebrospinal fluid and subarachnoid space and the blood circulation in the dura. The arachnoid barrier layer is characterized by a distinct continuous basal lamina on its inner surface toward the innermost collagenous portion of the arachnoid reticular layer. There are two subdivisions of arachnoid mater within the velum interpositum, the dorsal layer and the ventral layer. The dorsal layer covers internal cerebral veins and fixes them to the surrounding tela choroidea. The ventral layer of arachnoid membrane, on the other hand, is a direct anterior extension of this arachnoid envelope that the dorsal layer forms over the pineal region. Meninges Diagrammatic section of scalp. The medulla spinalis and its membranes. Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view. Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view. Arachnoid granulation  Arachnoid trabeculae
Denticulate ligaments
M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug (N1A/2AB/C/3/4/7A/B/C/D) Posterior/PCML: touch: Gracile  Cuneate
Lateral: proprioception: Spinocerebellar (Dorsal, Ventral)  pain/temp: Spinothalamic (Lateral, Anterior)  Posterolateral (Lissauer)  Spinotectal M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
Pia mater ( or ) often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. Pia mater is medieval Latin meaning "tender mother." The other two meningeal membranes are the dura mater and the arachnoid mater. Pia mater is a thin fibrous tissue that is impermeable to fluid. This allows the pia mater to enclose cerebrospinal fluid. By containing this fluid the pia mater works with the other meningeal layers to protect and cushion the brain. The pia mater allows blood vessels to pass through and nourish the brain. The perivascular space created between blood vessels and pia mater functions as a lymphatic system for the brain. When the pia mater becomes irritated and inflamed the result is meningitis. Pia mater is the thin, translucent, mesh-like meningeal envelope, spanning nearly the entire surface of the brain. It is absent only at the natural openings between the ventricles, the foramen of Majendie, and the foramina of Luschka. The pia firmly adheres to the surface of the brain and loosely connects to the arachnoid layer. Because of this continuum, the layers are often referred to as the pia arachnoid or leptomeninges. A subarachnoid space exists between the arachnoid layer and the pia, into which the choroid plexus releases and maintains the cerebrospinal fluid (CSF). The subarachnoid space contains trabeculae, or fibrous filaments, that connect and bring stability to the two layers, allowing for the appropriate protection from and movement of the proteins, electrolytes, ions, and glucose contained within the CSF. The thin membrane is composed of fibrous connective tissue, which is covered by a sheet of flat cells impermeable to fluid on its outer surface. A network of blood vessels travels to the brain and spinal cord by interlacing through the pia membrane. These capillaries are responsible for nourishing the brain. This vascular membrane is held together by areolar tissue covered by mesothelial cells from the delicate strands of connective tissue called the arachnoid trabeculae. In the perivascular spaces, the pia mater begins as mesothelial lining on the outer surface, but the cells then fade to be replaced by neuroglia elements. Although the pia mater is primarily structurally similar throughout, it spans both the spinal cord’s neural tissue and runs down the fissures of the cerebral cortex in the brain. It is often broken down into two categories, the cranial pia mater (pia mater encephali) and the spinal pia mater (pia mater spinalis). The section of the pia mater enveloping the brain is known as the cranial pia mater. It is anchored to the brain by the processes of astrocytes, which are glial cells responsible for many functions, including maintenance of the extracellular space. The cranial pia mater joins with the ependyma, which lines the cerebral ventricles to form choroid plexuses that produce cerebrospinal fluid. Together with the other meningeal layers, the function of the pia mater is to protect the central nervous system by containing the cerebrospinal fluid, which cushions the brain and spine. The cranial pia mater covers the surface of the brain. This layer goes in between the cerebral gyri and cerebellar laminae, folding inward to create the tela chorioidea of the third ventricle and the choroid plexuses of the lateral and third ventricles. At the level of the cerebellum, the pia mater membrane is more fragile due to the length of blood vessels as well as decreased connection to the cerebral cortex. The spinal pia mater closely follows the curves of the spinal cord. It encloses the surface of the medulla spinalis, or spinal cord, and is attached to it through a connection to the anterior fissure. The pia mater attaches to the dura mater through 21 pairs of denticulate ligaments that pass through the arachnoid mater and dura mater of the spinal cord. These denticular ligaments help to anchor the spinal cord and prevent side to side movement, providing stability. The membrane in this area is much thicker than the cranial pia mater, due to the two-layer composition of the pia membrane. The outer layer, which is made up of mostly connective tissue, is responsible for this thickness. Between the two layers are spaces which exchange information with the subarachnoid cavity as well as blood vessels. At the point where the pia mater reaches the conus medullaris or medullary cone at the end of the spinal cord, the membrane extends as a thin filament called the filum terminale or terminal filum, contained within the lumbar cistern. This filament eventually blends with the dura mater and extends as far as the coccyx, or tailbone. It then fuses with the periosteum, a membrane found at the surface of all bones, and forms the coccygeal ligament. Here it is called the central ligament and assists with movements of the trunk of the body. The pia mater is a neural crest derivative. Meninges of the CNS Median sagittal section of brain Coronal section of inferior horn of lateral ventricle Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. Diagrammatic section of scalp In conjunction with the other meningeal membranes, pia mater functions to cover and protect the central nervous system (CNS), to protect the blood vessels and enclose the venous sinuses near the CNS, to contain the cerebrospinal fluid (CSF) and to form partitions with the skull. The CSF, pia mater, and other layers of the meninges work together as a protection device for the brain, with the CSF often referred to as the fourth layer of the meninges. Cerebrospinal fluid is circulated through the ventricles, cisterns, and subarachnoid space within the brain and spinal cord. About 150 mL of CSF is always in circulation, constantly being recycled through the daily production of nearly 500 mL of fluid. The CSF is primarily secreted by the choroid plexus, however about one-third of the CSF is secreted by pia mater and the other ependymal surfaces of the ventricles and arachnoidal membranes. The ependymal surface refers to the thin epithelial membrane lining the brain and spinal cord canal. The CSF travels from the ventricles and cerebellum through three foramen in the brain, emptying into the cerebrum, and ending its cycle in the venous blood. The pia spans every surface crevice of the brain besides the foramen to allow the circulation of CSF to continue. Pia mater allows for the formation of perivascular spaces that help serve as the brain’s lymphatic system. Blood vessels that penetrate the brain first pass across the surface and then go inwards toward the brain. This direction of flow leads to a layer of the pia mater being carried inwards and loosely adhering to the vessels, leading to the production of a space, namely a perivascular space, between the pia mater and each blood vessel. This is critical because the brain lacks a true lymphatic system. In the remainder of the body, small amounts of protein are able to leak from the parenchymal capillaries through the lymphatic system. In the brain, this ends up in the interstitial space. The protein portions are able to leave through the very permeable pia mater and enter the subarachnoid space in order to flow in the cerebrospinal fluid (CSF), eventually ending up in the cerebral veins. The pia mater serves to create these perivascular spaces to allow passage of certain material, such as fluids, proteins, and even extraneous particulate matter such as dead white blood cells from the blood stream to the CSF, and essentially the brain. Pia mater see blood–brain barrier (BBB). The BBB is responsible for keeping the CSF and brain fluid separate from the blood, allowing limited sodium, chlorine, and potassium through, and absolutely no plasma proteins nor organic molecules. Nearby, the ventricles are lined with the ependyma membrane. The CSF is only kept separate through the pia mater. Due to the ependyma and pia mater’s high permeability, nearly anything entering the CSF is able to enter the brain interstitial fluid. However, regulation of this permeability is achieved through the abundant amount of astrocyte foot processes which are responsible for connecting the capillaries and the pia mater in a way that helps limit the amount of free diffusion going into the CNS. The permeability of the pia then serves to closely connect the interstitial brain fluid and the CSF and allow them to remain nearly homogenous in terms of composition. The function of the pia mater is more simply visualized through these ordinary occurrences. This last property is evident in cases of head injury. When the head comes into contact with another object, the brain is protected from the skull due to the similarity in density between these two fluids so that the brain does not simply smash through into the skull, but rather its movement is slowed and stopped by the viscous ability of this fluid. The contrast in permeability between the BBB and pia mater mentioned before is also useful in the application of medicine. Drugs that enter the blood stream can not penetrate and function in the brain, but instead must be administered into the cerebrospinal fluid. The pia mater also functions to deal with the deformation of the spinal cord under compression. Due to the high elastic modulus of the pia mater, it is able to provide a constraint on the surface of the spinal cord. This constraint stops the elongation of the spinal cord, as well as providing a high strain energy. This high strain energy is useful and responsible for the restoration of the spinal cord to its original shape following a period of decompression. Ventral root afferents are unmyelinated sensory axons located within the pia mater. These ventral root afferents relay sensory information from the pia mater and allow for the transmission of pain from disc herniation and other spinal injury. The significant increase in the size of the cerebral hemisphere through evolution has been made possible in part through the evolution of the vascular pia mater, which allows nutrient blood-vessels to penetrate deep into the intertwined cerebral matter, providing the necessary nutrients in this larger neural mass. Throughout the course of life on earth, the nervous system of animals has continued to evolve to a more compact and increased organization of neurons and other nervous system cells. This process is most evident in vertebrates and especially mammals in which the increased size of the brain is generally condensed into a smaller space through the presence of sulci or fissures on the surface of the hemisphere divided into gyri allowing more superficies of the cortical grey matter to exist. The development of the meninges and the existence of a defined pia mater was first noted in the vertebrates, and has been more and more significant membrane in the brains of mammals with larger brains. Meningitis is the inflammation of the pia and arachnoid mater. This is often due to bacteria that have entered the subarachnoid space, but can also be caused by viruses, fungi, as well as non-infectious causes such as certain drugs. It is believed that bacterial meningitis is caused by bacteria that enter the central nervous system through the blood stream. The molecular tools these pathogens would require to cross the meningeal layers and the blood–brain barrier are not yet well understood. Inside the subarachnoid, bacteria replicate and cause inflammation from released toxins such as hydrogen peroxide (H2O2) . These toxins have been found to damage the mitochondria and produce a large scale immune response. Headache and meningismus are often signs of inflammation relayed via trigeminal sensory nerve fibers within the pia mater. Disabling neuropsychological effects are seen in up to half of bacterial meningitis survivors. Research into how bacteria invade and enter the memingeal layers is the next step in prevention of the progression of meningitis. A tumor growing from the meninges is referred to as a meningioma. Most meningiomas grow from the arachnoid mater inward applying pressure on the pia mater and therefore the brain or spinal cord. While meningiomas make up 20% of primary brain tumors and 12% of spinal cord tumors, 90% of these tumors are benign. Meningiomas tend to grow slowly and therefore symptoms may arise years after initial tumor formation. The symptoms often include headaches and seizures due to the force the tumor creates on sensory receptors. The current treatments available for these tumors include surgery and radiation. Research is constantly ongoing involving the pia mater. A group of hospitals in Madrid, Spain published an article in 2004 based on the ultrastructural findings in human spinal pia mater in relation to subarachnoid anesthesia. The group was researching whether or not fenestrations were present in the pia mater membrane, and the effect they have on the transfer of local anesthetics across the membrane. Based on their research, fenestrations were found at the thoracic-lumbar junction, the conus medullaris, and nerve root levels. Although proving the presence of fenestrations in certain regions involving the pia mater, the group concluded that they could not determine the significance behind these fenestrations. They speculated the fenestrations at the lumbar spinal level may in fact facilitate the movement of local anesthetics across the pia mater membrane, which could in turn affect the onset time and latency of a subarachnoid block. Although no officially conclusion was made, research is still being done to prove their speculation. Arachnoid granulation  Arachnoid trabeculae
Denticulate ligaments
M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
The meninges is the system of membranes that envelope the central nervous system. In mammals, the meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system. Meninges () is the plural of meninx ( or ), from Ancient Greek:   "membrane". The adjective form is meningeal . The dura mater [Latin: 'tough mother'] (also rarely called meninx fibrosa or pachymeninx) is a thick, durable membrane, closest to the skull. It consists of two layers: the periosteal layer, which lies closest to the calvaria (skull)—and the inner meningeal layer, which lies closer to the brain. It contains larger blood vessels that split into the capillaries in the pia mater. It is composed of dense fibrous tissue, and its inner surface is covered by flattened cells like those present on the surfaces of the pia mater and arachnoid mater. The dura mater is a sac which envelops the arachnoid mater and surrounds and supports the large venous channels (dural sinuses) carrying blood from the brain toward the heart. The dura has four areas of infolding: The middle element of the meninges is the arachnoid mater, so named because of its spider web-like appearance. It provides a cushioning effect for the central nervous system. The arachnoid mater is a thin, transparent membrane. It is composed of fibrous tissue and, like the pia mater, is covered by flat cells also thought to be impermeable to fluid. The arachnoid does not follow the convolutions of the surface of the brain and so looks like a loosely fitting sac. In the region of the brain, particularly, a large number of fine filaments called arachnoid trabeculae pass from the arachnoid through the subarachnoid space to blend with the tissue of the pia mater. The arachnoid and pia mater are sometimes together called the leptomeninges. The pia mater [Latin: 'soft mother'] is a very delicate membrane. It is the meningeal envelope that firmly adheres to the surface of the brain and spinal cord, following the brain's minor contours (gyri and sulci). It is a very thin membrane composed of fibrous tissue covered on its outer surface by a sheet of flat cells thought to be impermeable to fluid. The pia mater is pierced by blood vessels to the brain and spinal cord, and its capillaries nourish the brain. The subarachnoid space is the space that normally exists between the arachnoid and the pia mater, which is filled with cerebrospinal fluid. Normally, the dura mater is attached to the skull, or to the bones of the vertebral canal in the spinal cord. The arachnoid is attached to the dura mater, while the pia mater is attached to the central nervous system tissue. When the dura mater and the arachnoid separate through injury or illness, the space between them is the subdural space. There are three types of hemorrhage involving the meninges: Other medical conditions that affect the meninges include meningitis (usually from fungal, bacterial, or viral infection) and meningiomas that arise from the meninges, or from meningeal carcinomatoses (tumors) that form elsewhere in the body and metastasize to the meninges. In fish, the meninges is a single membrane (the primitive meninx). In amphibians, reptiles and birds, the meninges include a thick outer dura mater and a thick inner secondary meninx. Mammals retain the dura mater, and the secondary meninx divides into the arachnoid and pia mater. Diagrammatic representation of a section across the top of the skull Diagrammatic section of scalp. M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug (N1A/2AB/C/3/4/7A/B/C/D) M: PNS anat (h/r/t/c/b/l/s/a)/phys (r)/devp/prot/nttr/nttm/ntrp noco/auto/cong/tumr, sysi/epon, injr proc, drug (N1B) Arachnoid granulation  Arachnoid trabeculae
Denticulate ligaments
M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
In the central nervous system, the subarachnoid cavity (subarachnoid space) is the interval between the arachnoid membrane and pia mater. It is occupied by spongy tissue consisting of trabeculae (delicate connective tissue filaments that extend from the arachnoid mater and blend into the pia mater) and intercommunicating channels in which the cerebrospinal fluid is contained. This cavity is small on the surface of the hemispheres of the brain. On the summit of each gyrus the pia mater and the arachnoid are in close contact, but in the sulci between the gyri, triangular spaces are left, in which the subarachnoid trabecular tissue is found. Whilst the pia mater closely follows the surface of the brain and dips into the sulci, the arachnoid bridges across them from gyrus to gyrus. At certain parts of the base of the brain, the arachnoid is separated from the pia mater by wide intervals, which communicate freely with each other and are named subarachnoid cisternæ; in these the subarachnoid tissue is less abundant. The subarachnoid space is the location of the interface between the vascular tissue and the cerebrospinal fluid and is active in the blood brain barrier. The arachnoid mater continues down the spinal cord too, and the subarachnoid layer with it. It serves a similar function in the spinal cord as it does in the brain. This article incorporates text from a public domain edition of Gray's Anatomy. Arachnoid granulation  Arachnoid trabeculae
Denticulate ligaments
M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
A cerebrospinal fluid leak (CSFL) is a medical condition when the cerebrospinal fluid of a person leaks out of the dura mater. This can be caused by several reasons, including spontaneous cerebrospinal fluid leak, post-surgical lumbar puncture (iatrogenic), physical trauma, etc. While high CSF pressure can make reclining unbearable, low CSF pressure due to a leak is often relieved somewhat by maintaining a supine position.

The central nervous system (CNS) is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except radially symmetric animals such as sponges and jellyfish. It contains the majority of the nervous system and consists of the brain and the spinal cord. Some classifications also include the retina and the second cranial nerve as parts of the CNS. Together with the peripheral nervous system, it has a fundamental role in the control of behavior. The CNS is contained within the dorsal cavity, with the brain in the cranial cavity and the spinal cord in the spinal cavity. In vertebrates, the brain is protected by the skull, while the spinal cord is protected by the vertebrae, and both are enclosed in the meninges.

During early development of the vertebrate embryo, a longitudinal groove on the neural plate gradually deepens and the ridges on either side of the groove (the neural folds) become elevated, and ultimately meet, transforming the groove into a closed tube, the ectodermal wall of which forms the rudiment of the nervous system. This tube initially differentiates into three vesicles (pockets): the prosencephalon at the front, the mesencephalon, and, between the mesencephalon and the spinal cord, the rhombencephalon. (By six weeks in the human embryo) the prosencephalon then divides further into the telencephalon and diencephalon; and the rhombencephalon divides into the metencephalon and myelencephalon.

Spontaneous cerebrospinal fluid leak syndrome (SCSFLS) is a medical condition in which the cerebrospinal fluid (CSF) held in and around a human brain and spinal cord leaks out of the surrounding protective sac, the dura, for no apparent reason. The dura, a tough, inflexible tissue, is the outermost of the three layers of the meninges, the system of meninges surrounding the brain and spinal cord. (The other two meningeal layers are the pia mater and the arachnoid mater).

A spontaneous cerebrospinal fluid leak is one of several types of cerebrospinal fluid leaks and occurs due to the presence of one or more holes in the dura. A spontaneous CSF leak, as opposed to traumatically caused CSF leaks, arises idiopathically. A loss of CSF greater than its rate of production leads to a decreased volume inside the skull known as intracranial hypotension. A CSF leak is most often characterized by a severe and disabling headache and a spectrum of various symptoms which occur as a result of intracerebral hemorrhage (ICH). These symptoms can include: dizziness, nausea, fatigue, a metallic taste in the mouth (indicative of a cranial leak), myoclonus, tinnitus, tingling in the limbs, and facial weakness amongst others. A CT scan can identify the site of a cerebrospinal fluid leakage. Once identified, the leak can often be repaired by an epidural blood patch, an injection of the patient's own blood at the site of the leak, fibrin glue injection or surgery.

A cerebrospinal fluid leak (CSFL) is a medical condition when the cerebrospinal fluid of a person leaks out of the dura mater. This can be caused by several reasons, including spontaneous cerebrospinal fluid leak, post-surgical lumbar puncture (iatrogenic), physical trauma, etc. While high CSF pressure can make reclining unbearable, low CSF pressure due to a leak is often relieved somewhat by maintaining a supine position.


Neurology

Cerebrospinal fluid (CSF) is a clear colorless bodily fluid found in the brain and spine. It is produced in the choroid plexus of the brain. It acts as a cushion or buffer for the cortex, providing a basic mechanical and immunological protection to the brain inside the skull, and it serves a vital function in cerebral autoregulation of cerebral blood flow.

The CSF occupies the subarachnoid space (the space between the arachnoid mater and the pia mater) and the ventricular system around and inside the brain and spinal cord. It constitutes the content of the ventricles, cisterns, and sulci of the brain, as well as the central canal of the spinal cord.

Syringomyelia

A pseudomeningocele is an abnormal collection of cerebrospinal fluid (CSF) that communicates with the CSF space around the brain or spinal cord. In contrast to a meningocele, in which the fluid is surrounded and confined by dura mater, in a pseudomeningocele, the fluid has no surrounding membrane but is contained in a cavity within the soft tissues.

Pseudomeningocele may result after brain surgery, spine surgery, or brachial plexus avulsion injury.

Anatomy

The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain (the medulla oblongata specifically). The brain and spinal cord together make up the central nervous system (CNS). The spinal cord begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column. It is around 45 cm (18 in) in men and around 43 cm (17 in) long in women. Also, the spinal cord has a varying width, ranging from 1/2 inch thick in the cervical and lumbar regions to 1/4 inch thick in the thoracic area. The enclosing bony vertebral column protects the relatively shorter spinal cord. The spinal cord functions primarily in the transmission of neural signals between the brain and the rest of the body but also contains neural circuits that can independently control numerous reflexes and central pattern generators. The spinal cord has three major functions: as a conduit for motor information, which travels down the spinal cord, as a conduit for sensory information in the reverse direction, and finally as a center for coordinating certain reflexes.

The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. The length of the spinal cord is much shorter than the length of the bony spinal column. The human spinal cord extends from the foramen magnum and continues through to the conus medullaris near the second lumbar vertebra, terminating in a fibrous extension known as the filum terminale.

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