Lumbar puncture | |
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![]() Lumbar puncture in a sitting position. The reddish-brown swirls on the patient's back are tincture of iodine (an antiseptic). | |
Other names | Spinal tap |
ICD-9-CM | 03.31 |
MeSH | D013129 |
eMedicine | 80773 |
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 (pressure in the skull) is a contraindication, due to risk of brain matter being compressed and pushed toward the spine. Sometimes, lumbar puncture cannot be performed safely (for example due to a severe bleeding tendency). It is regarded as a safe procedure, but post-dural-puncture headache is a common side effect if a small atraumatic needle is not used. [1]
The procedure is typically performed under local anesthesia using a sterile technique. A hypodermic needle is used to access the subarachnoid space and collect fluid. Fluid may be sent for biochemical, microbiological, and cytological analysis. Using ultrasound to landmark may increase success. [2]
Lumbar puncture was first introduced in 1891 by the German physician Heinrich Quincke.
The reason for a lumbar puncture may be to make a diagnosis [3] [4] [5] or to treat a disease, as outlined below. [4]
The chief diagnostic indications of lumbar puncture are for collection of cerebrospinal fluid (CSF). Analysis of CSF may exclude infectious, [4] [6] inflammatory, [4] and neoplastic diseases [4] affecting the central nervous system. The most common purpose is in suspected meningitis, [7] since there is no other reliable tool with which meningitis, a life-threatening but highly treatable condition, can be excluded. A lumbar puncture can also be used to detect whether someone has Stage 1 or Stage 2 Trypanosoma brucei . Young infants commonly require lumbar puncture as a part of the routine workup for fever without a source. [8] This is due to higher rates of meningitis than in older persons. Infants also do not reliably show classic symptoms of meningeal irritation (meningismus) like neck stiffness and headache the way adults do. [7] In any age group, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension, and many other diagnoses may be supported or excluded with this test. It may also be used to detect the presence of malignant cells in the CSF, as in carcinomatous meningitis or medulloblastoma. CSF containing less than 10 red blood cells (RBCs)/mm3 constitutes a "negative" tap in the context of a workup for subarachnoid hemorrhage, for example. Taps that are "positive" have an RBC count of 100/mm³ or more. [9]
Lumbar punctures may also be done to inject medications into the cerebrospinal fluid ("intrathecally"), particularly for spinal anesthesia [10] or chemotherapy.
Serial lumbar punctures may be useful in temporary treatment of idiopathic intracranial hypertension (IIH). This disease is characterized by increased pressure of CSF which may cause headache and permanent loss of vision. While mainstays of treatment are medication, in some cases lumbar puncture performed multiple times may improve symptoms. It is not recommended as a staple of treatment due to discomfort and risk of the procedure, and the short duration of its efficacy. [11] [12]
Additionally, some people with normal pressure hydrocephalus (characterized by urinary incontinence, a changed ability to walk properly, and dementia) receive some relief of symptoms after removal of CSF. [13]
Lumbar puncture should not be performed in the following situations:
Post-dural-puncture headache with nausea is the most common complication; it often responds to pain medications and infusion of fluids. It was long taught that this complication can be prevented by strict maintenance of a supine posture for two hours after the successful puncture; this has not been borne out in modern studies involving large numbers of people. Doing the procedure with the person on their side might decrease the risk. [16] Intravenous caffeine injection is often quite effective in aborting these spinal headaches. A headache that is persistent despite a long period of bedrest and occurs only when sitting up may be indicative of a CSF leak from the lumbar puncture site. It can be treated by more bedrest, or by an epidural blood patch, where the person's own blood is injected back into the site of leakage to cause a clot to form and seal off the leak. [17]
The risk of headache and need for analgesia and blood patch is much reduced if "atraumatic" needles are used. This does not affect the success rate of the procedure in other ways. [18] [19] Although the cost and difficulty are similar, adoption remains low, at only 16% c. 2014. [20]
The headaches may be caused by inadvertent puncture of the dura mater. [21]
Contact between the side of the lumbar puncture needle and a spinal nerve root can result in anomalous sensations (paresthesia) in a leg during the procedure; this is harmless and people can be warned about it in advance to minimize their anxiety if it should occur.
Serious complications of a properly performed lumbar puncture are extremely rare. [4] They include spinal or epidural bleeding, adhesive arachnoiditis and trauma to the spinal cord [10] or spinal nerve roots resulting in weakness or loss of sensation, or even paraplegia. The latter is exceedingly rare, since the level at which the spinal cord ends (normally the inferior border of L1, although it is slightly lower in infants) is several vertebral spaces above the proper location for a lumbar puncture (L3/L4). There are case reports of lumbar puncture resulting in perforation of abnormal dural arterio-venous malformations, resulting in catastrophic epidural hemorrhage; this is exceedingly rare. [10]
The procedure is not recommended when epidural infection is present or suspected, when topical infections or dermatological conditions pose a risk of infection at the puncture site or in patients with severe psychosis or neurosis with back pain. Some authorities believe that withdrawal of fluid when initial pressures are abnormal could result in spinal cord compression or cerebral herniation; others believe that such events are merely coincidental in time, occurring independently as a result of the same pathology that the lumbar puncture was performed to diagnose. In any case, computed tomography of the brain is often performed prior to lumbar puncture if an intracranial mass is suspected. [22]
CSF leaks can result from a lumbar puncture procedure. [23] [24] [25] [26]
The brain and spinal cord are enveloped by a layer of cerebrospinal fluid, 125–150 mL in total (in adults) which acts as a shock absorber and provides a medium for the transfer of nutrients and waste products. The majority is produced by the choroid plexus in the brain and circulates from there to other areas, before being reabsorbed into the circulation (predominantly by the arachnoid granulations). [27]
The cerebrospinal fluid can be accessed most safely in the lumbar cistern. Below the first or second lumbar vertebrae (L1 or L2) the spinal cord terminates (conus medullaris). Nerves continue down the spine below this, but in a loose bundle of nerve fibers called the cauda equina. There is lower risk with inserting a needle into the spine at the level of the cauda equina because these loose fibers move out of the way of the needle without being damaged. [27] The lumbar cistern extends into the sacrum up to the S2 vertebra. [27]
The person is usually placed on their side (left more commonly than right). The patient bends the neck so the chin is close to the chest, hunches the back, and brings knees toward the chest. This approximates a fetal position as much as possible. Patients may also sit on a stool and bend their head and shoulders forward. The area around the lower back is prepared using aseptic technique. Once the appropriate location is palpated, local anaesthetic is infiltrated under the skin and then injected along the intended path of the spinal needle. A spinal needle is inserted between the lumbar vertebrae L3/L4, L4/L5 [10] or L5/S1 [10] and pushed in until there is a "give" as it enters the lumbar cistern wherein the ligamentum flavum is housed. The needle is again pushed until there is a second 'give' that indicates the needle is now past the dura mater. The arachnoid membrane and the dura mater exist in flush contact with one another in the living person's spine due to fluid pressure from CSF in the subarachnoid space pushing the arachnoid membrane out towards the dura. Therefore, once the needle has pierced the dura mater it has also traversed the thinner arachnoid membrane. The needle is then in the subarachnoid space. The stylet from the spinal needle is then withdrawn and drops of cerebrospinal fluid are collected. The opening pressure of the cerebrospinal fluid may be taken during this collection by using a simple column manometer. The procedure is ended by withdrawing the needle while placing pressure on the puncture site. The spinal level is so selected to avoid spinal injuries. [10] In the past, the patient would lie on their back for at least six hours and be monitored for signs of neurological problems. There is no scientific evidence that this provides any benefit. The technique described is almost identical to that used in spinal anesthesia, except that spinal anesthesia is more often done with the patient in a seated position.[ citation needed ]
The upright seated position is advantageous in that there is less distortion of spinal anatomy which allows for easier withdrawal of fluid. Some practitioners prefer it for lumbar puncture in obese patients, where lying on their side would cause a scoliosis and unreliable anatomical landmarks. However, opening pressures are notoriously unreliable when measured in the seated position. Therefore, patients will ideally lie on their side if practitioners need to measure opening pressure.[ citation needed ]
Reinsertion of the stylet may decrease the rate of post lumbar puncture headaches. [15]
Although not available in all clinical settings, use of ultrasound is helpful for visualizing the interspinous space and assessing the depth of the spine from the skin. Use of ultrasound reduces the number of needle insertions and redirections, and results in higher rates of successful lumbar puncture. [28] If the procedure is difficult, such as in people with spinal deformities such as scoliosis, it can also be performed under fluoroscopy (under continuous X-ray imaging). [29]
In children, a sitting flexed position was as successful as lying on the side with respect to obtaining non-traumatic CSF, CSF for culture, and cell count. There was a higher success rate in obtaining CSF in the first attempt in infants younger than 12 months in the sitting flexed position. [30]
The spine of an infant at the time of birth differs from the adult spine. The conus medullaris (bottom of the spinal cord) terminates at the level of L1 in adults, but may range in term neonates (newly born babies) from L1–L3 levels. [31] It is important to insert the spinal needle below the conus medullaris at the L3/L4 or L4/L5 interspinous levels. [32] With growth of the spine, the conus typically reaches the adult level (L1) by 2 years of age. [31]
The ligamentum flavum and dura mater are not as thick in infants and children as they are in adults. Therefore, it is difficult to assess when the needle passes through them into the subarachnoid space because the characteristic "pop" or "give" may be subtle or nonexistent in the pediatric lumbar puncture. To decrease the chances of inserting the spinal needle too far, some clinicians use the "Cincinnati" method. This method involves removing the stylet of the spinal needle once the needle has advanced through the dermis. After removal of the stylet, the needle is inserted until CSF starts to come out of the needle. Once all of the CSF is collected, the stylet is then reinserted before removal of the needle. [32]
Lumbar punctures are often used to diagnose or verify an infection in very young babies and can cause quite a bit of pain unless appropriate pain control is used (analgesia). [8] Managing pain is important for infants undergoing this procedure. [8] Approaches for pain control include topical pain medications (anaesthetics such as lidocaine). The most effective approach for pain control in infants who require a lumbar puncture is not clear. [8]
Analysis of the cerebrospinal fluid generally includes a cell count and determination of the glucose and protein concentrations. The other analytical studies of cerebrospinal fluid are conducted according to the diagnostic suspicion. [4]
Increased CSF pressure can indicate congestive heart failure, cerebral edema, subarachnoid hemorrhage, hypo-osmolality resulting from hemodialysis, meningeal inflammation, purulent meningitis or tuberculous meningitis, hydrocephalus, or pseudotumor cerebri. [27] In the setting of raised pressure (or normal pressure hydrocephalus, where the pressure is normal but there is excessive CSF), lumbar puncture may be therapeutic. [27]
Decreased CSF pressure can indicate complete subarachnoid blockage, leakage of spinal fluid, severe dehydration, hyperosmolality, or circulatory collapse. Significant changes in pressure during the procedure can indicate tumors or spinal blockage resulting in a large pool of CSF, or hydrocephalus associated with large volumes of CSF. [27]
The presence of white blood cells in cerebrospinal fluid is called pleocytosis. A small number of monocytes can be normal; the presence of granulocytes is always an abnormal finding. A large number of granulocytes often heralds bacterial meningitis. White cells can also indicate reaction to repeated lumbar punctures, reactions to prior injections of medicines or dyes, central nervous system hemorrhage, leukemia, recent epileptic seizure, or a metastatic tumor. When peripheral blood contaminates the withdrawn CSF, a common procedural complication, white blood cells will be present along with erythrocytes, and their ratio will be the same as that in the peripheral blood.[ citation needed ]
The finding of erythrophagocytosis, [33] where phagocytosed erythrocytes are observed, signifies haemorrhage into the CSF that preceded the lumbar puncture. Therefore, when erythrocytes are detected in the CSF sample, erythrophagocytosis suggests causes other than a traumatic tap, such as intracranial haemorrhage and haemorrhagic herpetic encephalitis. In which case, further investigations are warranted, including imaging and viral culture.[ citation needed ]
CSF can be sent to the microbiology lab for various types of smears and cultures to diagnose infections.
Several substances found in cerebrospinal fluid are available for diagnostic measurement.
Infection | Appearance [54] | WBCs / mm3 [55] | Protein (g/L) [55] | Glucose [55] |
---|---|---|---|---|
Normal | Clear | <5 | 0.15 to 0.45 | > 2/3 of blood glucose |
Bacterial | Yellowish, turbid | > 1,000 (mostly PMNs) | > 1 | Low |
Viral | Clear | < 200 (mostly lymphocytes) | Mild increase | Normal or mildly low |
Tuberculosis | Yellowish and viscous | Modest increase | Markedly Increased | Decreased |
Fungal | Yellowish and viscous | < 50 (mostly lymphocytes) | Initially normal, then increased | Normal or mildly low |
The first technique for accessing the dural space was described by the London physician Walter Essex Wynter. In 1889 he developed a crude cut down with cannulation in four patients with tuberculous meningitis. The main purpose was the treatment of raised intracranial pressure rather than for diagnosis. [56] The technique for needle lumbar puncture was then introduced by the German physician Heinrich Quincke, who credits Wynter with the earlier discovery; he first reported his experiences at an internal medicine conference in Wiesbaden, Germany, in 1891. [57] He subsequently published a book on the subject. [58] [59]
The lumbar puncture procedure was taken to the United States by Arthur H. Wentworth an assistant professor at the Harvard Medical School, based at Children's Hospital. In 1893 he published a long paper on diagnosing cerebrospinal meningitis by examining spinal fluid. [60] However, he was criticized by antivivisectionists for having obtained spinal fluid from children. He was acquitted, but, nevertheless, he was uninvited from the then forming Johns Hopkins School of Medicine, where he would have been the first professor of pediatrics.[ citation needed ]
Historically lumbar punctures were also employed in the process of performing a pneumoencephalography, a nowadays obsolete X-ray imaging study of the brain that was performed extensively from the 1920s until the advent of modern non-invasive neuroimaging techniques such as MRI and CT in the 1970s. During this quite painful procedure, CSF was replaced with air or some other gas via the lumbar puncture in order to enhance the appearance of certain areas of the brain on plain radiographs.
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
Idiopathic intracranial hypertension (IIH), previously known as pseudotumor cerebri and benign intracranial hypertension, is a condition characterized by increased intracranial pressure without a detectable cause. The main symptoms are headache, vision problems, ringing in the ears, and shoulder pain. Complications may include vision loss.
Viral meningitis, also known as aseptic meningitis, is a type of meningitis due to a viral infection. It results in inflammation of the meninges. Symptoms commonly include headache, fever, sensitivity to light and neck stiffness.
Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary incontinence, personality changes, or mental impairment. In babies, it may be seen as a rapid increase in head size. Other symptoms may include vomiting, sleepiness, seizures, and downward pointing of the eyes.
Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 mmHg for a supine adult. This equals to 9–20 cmH2O, which is a common scale used in lumbar punctures. The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF.
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 usually performed by anesthesiologists that can be used as an alternative to general anesthesia commonly in surgeries involving the lower extremities and surgeries below the umbilicus. The local anesthetic with or without an opioid injected into the cerebrospinal fluid provides locoregional anaesthesia: true anaesthesia, motor, sensory and autonomic (sympathetic) blockade. Administering analgesics in the cerebrospinal fluid without a local anaesthetic produces locoregional analgesia: markedly reduced pain sensation, some autonomic blockade, but no sensory or motor block. Locoregional analgesia, due to mainly the absence of motor and sympathetic block may be preferred over locoregional anaesthesia in some postoperative care settings. The tip of the spinal needle has a point or small bevel. Recently, pencil point needles have been made available.
Normal pressure hydrocephalus (NPH), also called malresorptive hydrocephalus, is a form of communicating hydrocephalus in which excess cerebrospinal fluid (CSF) builds up in the ventricles, leading to normal or slightly elevated cerebrospinal fluid pressure. The fluid build-up causes the ventricles to enlarge and the pressure inside the head to increase, compressing surrounding brain tissue and leading to neurological complications. Although the cause of idiopathicNPH remains unclear, it has been associated with various co-morbidities including hypertension, diabetes mellitus, Alzheimer's disease, and hyperlipidemia. Causes of secondary NPH include trauma, hemorrhage, or infection. The disease presents in a classic triad of symptoms, which are memory impairment, urinary frequency, and balance problems/gait deviations. The disease was first described by Salomón Hakim and Raymond Adams in 1965.
Aseptic meningitis is the inflammation of the meninges, a membrane covering the brain and spinal cord, in patients whose cerebral spinal fluid test result is negative with routine bacterial cultures. Aseptic meningitis is caused by viruses, mycobacteria, spirochetes, fungi, medications, and cancer malignancies. The testing for both meningitis and aseptic meningitis is mostly the same. A cerebrospinal fluid sample is taken by lumbar puncture and is tested for leukocyte levels to determine if there is an infection and goes on to further testing to see what the actual cause is. The symptoms are the same for both meningitis and aseptic meningitis but the severity of the symptoms and the treatment can depend on the certain cause.
Myelography is a type of radiographic examination that uses a contrast medium to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors. Historically the procedure involved the injection of a radiocontrast agent into the cervical or lumbar spine, followed by several X-ray projections. Today, myelography has largely been replaced by the use of MRI scans, although the technique is still sometimes used under certain circumstances – though now usually in conjunction with CT rather than X-ray projections.
Tuberculous meningitis, also known as TB meningitis or tubercular meningitis, is a specific type of bacterial meningitis caused by the Mycobacterium tuberculosis infection of the meninges—the system of membranes which envelop the central nervous system.
Xanthochromia, from the Greek xanthos (ξανθός) "yellow" and chroma (χρώμα) "colour", is the yellowish appearance of cerebrospinal fluid that occurs several hours after bleeding into the subarachnoid space caused by certain medical conditions, most commonly subarachnoid hemorrhage. Its presence can be determined by either spectrophotometry or simple visual examination. It is unclear which method is superior.
Cisternography is a medical imaging technique to examine the flow of cerebrospinal fluid (CSF) in the brain, and spinal cord. The gold standard for diagnosis of a cranial cerebrospinal fluid leak is CT cisternography. For the diagnosis of a spinal CSF leak radionuclide cisternography also known as radioisotope cisternography is used. The false negative rate of cisternography is high (30%), so the radiographic study of choice is CT myelography. The third type of cisternography is MR cisternography.
Leptomeningeal cancer is a rare complication of cancer in which the disease spreads from the original tumor site to the meninges surrounding the brain and spinal cord. This leads to an inflammatory response, hence the alternative names neoplastic meningitis (NM), malignant meningitis, or carcinomatous meningitis. The term leptomeningeal describes the thin meninges, the arachnoid and the pia mater, between which the cerebrospinal fluid is located. The disorder was originally reported by Eberth in 1870. It is also known as leptomeningeal carcinomatosis, leptomeningeal disease (LMD), leptomeningeal metastasis, meningeal metastasis and meningeal carcinomatosis.
An epidural blood patch (EBP) is a surgical procedure that uses autologous blood, meaning the patient's own blood, in order to close one or many holes in the dura mater of the spinal cord, which occurred as a complication of a lumbar puncture or epidural placement. The punctured dura causes cerebrospinal fluid leak. The procedure can be used to relieve orthostatic headaches, most commonly post dural puncture headache (PDPH).
An external ventricular drain (EVD), also known as a ventriculostomy or extraventricular drain, is a device used in neurosurgery to treat hydrocephalus and relieve elevated intracranial pressure when the normal flow of cerebrospinal fluid (CSF) inside the brain is obstructed. An EVD is a flexible plastic catheter placed by a neurosurgeon or neurointensivist and managed by intensive care unit (ICU) physicians and nurses. The purpose of external ventricular drainage is to divert fluid from the ventricles of the brain and allow for monitoring of intracranial pressure. An EVD must be placed in a center with full neurosurgical capabilities, because immediate neurosurgical intervention can be needed if a complication of EVD placement, such as bleeding, is encountered.
Mollaret's meningitis is a recurrent or chronic inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. Since Mollaret's meningitis is a recurrent, benign (non-cancerous), aseptic meningitis, it is also referred to as benign recurrent lymphocytic meningitis. It was named for Pierre Mollaret, the French neurologist who first described it in 1944.
Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, intense headache, vomiting and neck stiffness and occasionally photophobia.
A cerebrospinal fluid leak is a medical condition where the cerebrospinal fluid (CSF) that surrounds the brain and spinal cord leaks out of one or more holes or tears in the dura mater. A CSF leak is classed as either spontaneous (primary), having no known cause, or nonspontaneous (secondary) where it is attributed to an underlying condition. Causes of a primary CSF leak are those of trauma including from an accident or intentional injury, or arising from a medical intervention known as iatrogenic. A basilar skull fracture as a cause can give the sign of CSF leakage from the ear nose or mouth. A lumbar puncture can give the symptom of a post-dural-puncture headache.
A lumbar–peritoneal shunt is a technique to channelise the cerebrospinal fluid (CSF) from the lumbar thecal sac into the peritoneal cavity.
Lymphocytic pleocytosis is an abnormal increase in the amount of lymphocytes in the cerebrospinal fluid (CSF). It is usually considered to be a sign of infection or inflammation within the nervous system, and is encountered in a number of neurological diseases, such as pseudomigraine, Susac's syndrome, and encephalitis. While lymphocytes make up roughly a quarter of all white blood cells (WBC) in the body, they are generally rare in the CSF. Under normal conditions, there are usually less than 5 white blood cells per μL of CSF. In a pleocytic setting, the number of lymphocytes can jump to more than 1,000 cells per μL. Increases in lymphocyte count are often accompanied by an increase in cerebrospinal protein concentrations in addition to pleocytosis of other types of white blood cells.
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