Cerebrospinal fluid (CSF) is a clear, colorless body fluid found in the brain and spinal cord. It is produced by specialised ependymal cells in the choroid plexuses of the ventricles of the brain, and absorbed in the arachnoid granulations. There is about 125mL of CSF at any one time, and about 500 mL is generated every day. CSF acts as a cushion or buffer, providing basic mechanical and immunological protection to the brain inside the skull. CSF also serves a vital function in the cerebral autoregulation of cerebral blood flow.
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.
The cauda equina is a bundle of spinal nerves and spinal nerve rootlets, consisting of the second through fifth lumbar nerve pairs, the first through fifth sacral nerve pairs, and the coccygeal nerve, all of which arise from the lumbar enlargement and the conus medullaris of the spinal cord. The cauda equina occupies the lumbar cistern, a subarachnoid space inferior to the conus medullaris. The nerves that compose the cauda equina innervate the pelvic organs and lower limbs to include motor innervation of the hips, knees, ankles, feet, internal anal sphincter and external anal sphincter. In addition, the cauda equina extends to sensory innervation of the perineum and, partially, parasympathetic innervation of the bladder.
The ventricular system is a set of four interconnected cavities in the brain, Within each ventricle is a region of choroid plexus where the cerebrospinal fluid (CSF) is produced. The ventricular system is continuous with the central canal of the spinal cord from the fourth ventricle, allowing for the flow of CSF to circulate.
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to help diagnose diseases of the central nervous system, including the brain and spine. Examples of these conditions include meningitis and subarachnoid hemorrhage. It may also be used therapeutically in some conditions. Increased intracranial pressure is a contraindication, due to risk of brain matter being compressed and pushed toward the spine. Sometimes, lumbar puncture cannot be performed safely. It is regarded as a safe procedure, but post-dural-puncture headache is a common side effect.
The meninges are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in the subarachnoid space between the arachnoid mater and the pia mater. The primary function of the meninges is to protect the central nervous system.
Dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. The other two meningeal layers are the arachnoid mater and the pia mater. The dura surrounds the brain and the spinal cord. It envelops the arachnoid mater, which is responsible for keeping in the cerebrospinal fluid. It is derived primarily from the neural crest cell population, with postnatal contributions of the paraxial mesoderm.
Spinal anaesthesia, also called spinal block, subarachnoid block, intradural block and intrathecal block, is a form of neuraxial regional anaesthesia involving the injection of a local anaesthetic or opioid into the subarachnoid space, generally through a fine needle, usually 9 cm (3.5 in) long. It is a safe and effective form of anesthesia performed by nurse anesthetists and anesthesiologists which can be used as an alternative to general anesthesia commonly in surgeries involving the lower extremities and surgeries below the umbilicus. The local anesthetic or opioid injected into the cerebrospinal fluid provides anesthesia, analgesia, and motor and sensory blockade. The tip of the spinal needle has a point or small bevel. Recently, pencil point needles have been made available.
The spinal cavity is the cavity that contains the spinal cord within the vertebral column, formed by the vertebrae through which the spinal cord passes. It is a process of the dorsal body cavity. This canal is enclosed within the vertebral foramen of the vertebrae. In the intervertebral spaces, the canal is protected by the ligamentum flavum posteriorly and the posterior longitudinal ligament anteriorly.
Epidural administration is a medical route of administration in which a drug such as epidural analgesia and epidural anaesthesia or contrast agent is injected into the epidural space around the spinal cord. The epidural route is frequently employed by certain physicians and nurse anaesthetists to administer local anaesthetic agents, and occasionally to administer diagnostic and therapeutic chemical substances. Epidural techniques frequently involve injection of drugs through a catheter placed into the epidural space. The injection can result in a loss of sensation—including the sensation of pain—by blocking the transmission of signals through nerve fibres in or near the spinal cord.
Dura mater is the outermost meningeal layer that covers the brain and spinal cord. It consists of two layers; the inner meningeal layer and the outer periosteal layer. The potential space between the layers of the dura mater is called the epidural space. The epidural space exists around both the brain and the spinal cord.
Neuromeres are morphologically or molecularly defined transient segments of the early developing brain. Rhombomeres are such segments that make up the rhombencephalon or hindbrain. More controversially, some argue that there exist early developmental segments that give rise to structures of the midbrain (mesomeres) and forebrain (prosomeres).
Intrathecal administration is a route of administration for drugs via an injection into the spinal canal, or into the subarachnoid space so that it reaches the cerebrospinal fluid (CSF) and is useful in spinal anesthesia, chemotherapy, or pain management applications. This route is also used to introduce drugs that fight certain infections, particularly post-neurosurgical. The drug needs to be given this way to avoid being stopped by the blood brain barrier. The same drug given orally must enter the blood stream and may not be able to pass out and into the brain. Drugs given by the intrathecal route often have to be compounded specially by a pharmacist or technician because they cannot contain any preservative or other potentially harmful inactive ingredients that are sometimes found in standard injectable drug preparations.
A suboccipital puncture or cisternal puncture is a diagnostic procedure that can be performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis, or rarely to relieve increased intracranial pressure. It is done by inserting a needle through the skin below the external occipital protuberance into the cisterna magna and is an alternative to lumbar puncture. Indications for its use are limited. Subarachnoid hemorrhage and direct puncture of brain tissue are the most common major complications. Fluoroscopic guidance decreases the risk for complications. The use of this procedure in humans was first described by Ayer in 1920.
Diastematomyelia is a congenital disorder in which a part of the spinal cord is split, usually at the level of the upper lumbar vertebra.
Post-dural-puncture headache (PDPH) is a complication of puncture of the dura mater. The headache is severe and described as "searing and spreading like hot metal", involving the back and front of the head and spreading to the neck and shoulders, sometimes involving neck stiffness. It is exacerbated by movement and sitting or standing and is relieved to some degree by lying down. Nausea, vomiting, pain in arms and legs, hearing loss, tinnitus, vertigo, dizziness and paraesthesia of the scalp are also common.
An epidural blood patch is a surgical procedure that uses autologous blood in order to close one or many holes in the dura mater of the spinal cord, usually as a result of a previous lumbar puncture. The procedure can be used to relieve post dural puncture headaches caused by lumbar puncture. A small amount of the patient's blood is injected into the epidural space near the site of the original puncture; the resulting blood clot then "patches" the meningeal leak. The procedure carries the typical risks of any epidural puncture. However, even though it is often effective, further intervention is sometimes necessary.
A spontaneous cerebrospinal fluid leak (SCSFL) is a medical condition in which the cerebrospinal fluid (CSF) surrounding the human brain and spinal cord leaks out of the surrounding protective dural sac for no apparent reason. The dura, a tough, inflexible tissue, is the outermost of the three layers of the meninges, the system of membranes surrounding the brain and spinal cord.
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and entering the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around 45 cm (18 in) in men and around 43 cm (17 in) long in women. The diameter of the spinal cord ranges from 13 mm in the cervical and lumbar regions to 6.4 mm in the thoracic area.
Tarlov cysts, are type II innervated meningeal cysts, cerebrospinal-fluid-filled (CSF) sacs most frequently located in the spinal canal of the S1-to-S5 region of the spinal cord, and can be distinguished from other meningeal cysts by their nerve-fiber-filled walls. Tarlov cysts are defined as cysts formed within the nerve-root sheath at the dorsal root ganglion. The etiology of these cysts is not well understood; some current theories explaining this phenomenon have not yet been tested or challenged but include increased pressure in CSF, filling of congenital cysts with one-way valves, inflammation in response to trauma and disease. They are named for American neurosurgeon Isadore Tarlov, who described them in 1938.
