Lumbar puncture

Lumbar puncture
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
[edit on Wikidata]

Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the

Lumbar puncture was first introduced in 1891 by the German physician Heinrich Quincke.

Medical uses

The reason for a lumbar puncture may be to make a diagnosis^[3][4][5] or to treat a disease, as outlined below.^[4]

Diagnosis

The chief diagnostic indications of lumbar puncture are for collection of

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]

Contraindications

Lumbar puncture should not be performed in the following situations:

• Idiopathic (unidentified cause)
  increased intracranial pressure
  (ICP)
  • Rationale: lumbar puncture in the presence of raised ICP may cause
    uncal herniation
  • Exception: therapeutic use of lumbar puncture to reduce ICP, but only if obstruction (for example in the third ventricle of the brain) has been ruled out
  • Precaution
    • CT brain, especially in the following situations
      • Age >65
      • Reduced GCS
      • Recent history of seizure
      • Focal neurological signs
      • Abnormal respiratory pattern
      • Hypertension with bradycardia and deteriorating consciousness
    • Ophthalmoscopy for papilledema
• Bleeding diathesis (relative)
  • Coagulopathy
  • Decreased platelet count (<50 x 10⁹/L)
• Infections
  • Skin infection at puncture site
• Vertebral deformities (scoliosis or kyphosis), in hands of an inexperienced physician.^[14][15]

Adverse effects

Headache

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 – only 16% ca. 2014.^[20]

The headaches may be caused by inadvertent puncture of the dura mater.^[21]

Other

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.

CSF leaks can result from a lumbar puncture procedure.^{[23][24][25][26]}

Technique

Mechanism

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]

Procedure

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

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]

Children

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

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]

Interpretation

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]

Pressure determination

Increased CSF pressure can indicate

CSF can be sent to the microbiology lab for various types of smears and cultures to diagnose infections.

• Gram staining may demonstrate gram positive bacteria in bacterial meningitis.^[34]
• Microbiological culture is the gold standard for detecting bacterial meningitis. Bacteria, fungi, and viruses can all be cultured by using different techniques.
• herpesvirus and enterovirus. It has high sensitivity and specificity for many infections of the CNS, is fast, and can be done with small volumes of CSF. Even though testing is expensive, cost analyses of PCR testing in neonatal patients demonstrated savings via reduced cost of hospitalization.^[35][36]
• Numerous antibody-mediated tests for CSF are available in some countries: these include rapid tests for antigens of common bacterial pathogens, treponemal titers for the diagnosis of neurosyphilis and Lyme disease, Coccidioides antibody, and others.^{[citation needed]}
• The India ink test is still used for detection of meningitis caused by Cryptococcus neoformans,^[37][38] but the cryptococcal antigen (CrAg) test has a higher sensitivity.^[39]

Chemistry

Several substances found in cerebrospinal fluid are available for diagnostic measurement.

• De Vivo disease.^[43]
• Increased glucose levels in the fluid can indicate diabetes, although the 60% rule still applies.[44]^[45]
• Increased levels of
  Reye's syndrome,^[49][50] hepatic coma, cirrhosis,^[48] hypercapnia and depression.^[51]
• Increased levels of lactate can occur the presence of cancer of the CNS, multiple sclerosis, heritable mitochondrial disease, low blood pressure, low serum phosphorus, respiratory alkalosis, idiopathic seizures, traumatic brain injury, cerebral ischemia, brain abscess, hydrocephalus, hypocapnia or bacterial meningitis.^[44]
• The enzyme lactate dehydrogenase can be measured to help distinguish meningitides of bacterial origin, which are often associated with high levels of the enzyme, from those of viral origin in which the enzyme is low or absent.^[52]
• Changes in total protein content of cerebrospinal fluid can result from pathologically increased permeability of the
  hemorrhage, polio, collagen disease or Guillain–Barré syndrome, leakage of CSF, increases in intracranial pressure, or hyperthyroidism
  . Very high levels of protein may indicate tuberculous meningitis or spinal block.
• IgG synthetic rate is calculated from measured IgG and total protein levels; it is elevated in immune disorders such as multiple sclerosis, transverse myelitis, and
  neuromyelitis optica of Devic. Oligoclonal bands
  may be detected in CSF but not in serum, suggesting intrathecal antibody production.

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