MD Consult: Mandell: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases

lumbar puncture complications
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Numerous complications have been associated with performance of lumbar puncture,^[1,6-8] ranging from mild discomfort with insertion of the spinal needle to life-threatening conditions. The most common complication after lumbar puncture is headache, which is generally observed in 10% to 25% of patients, although may occur in up to 60% of patients; the headache is characteristically absent when the patient is recumbent and appears rapidly when the patient stands. The headache is believed to be secondary to low CSF pressure as a result of continued leakage of CSF at the site of the lumbar puncture. The risk of headache may be reduced by using smaller gauge needles (≤20 gauge) or by placing the patient in the prone position for several hours after the procedure, although it is unclear whether the latter maneuver is effective in reducing the likelihood of headache after lumbar puncture. A recommendation from the American Academy of Neurology supports the use of atraumatic (Sprotte or Pajunk) needles, rather than the standard (Quincke) needle, to reduce the risk of post–lumbar puncture headache.^[9] Reinsertion of the stylet before needle removal has also been shown to decrease the risk of headache.^[7] The headache usually resolves within hours to days after the procedure. Persistent headache can be treated by use of a "blood patch," in which some of the patient's own venous blood is injected outside the meninges at the site of the lumbar puncture; this procedure seals the site of CSF leakage.

Infection may occur after lumbar puncture, but the incidence of infection is low even in patients with concomitant bacteremia.^[1] Although there have been conflicting studies on the risk of subsequent meningitis in patients who are bacteremic at the time of lumbar puncture, the importance of performing a diagnostic lumbar puncture in the appropriate clinical setting greatly outweighs any minor risk that the procedure itself might induce meningitis in a bacteremic patient. Lumbar puncture should not be performed in patients with established local infection in the lumbar space (e.g., spinal epidural abscess, spinal subdural empyema, or superficial or deep paraspinal infection); in these cases, CSF analysis should be obtained under fluoroscopic guidance via high cervical or cisternal puncture.

Local bleeding is a more common complication after lumbar puncture^[1,6,8]; 20% of patients have a so-called traumatic tap.^[10] Bleeding may occur from inadvertent puncture of the venous plexuses located dorsally and ventrally to the spinal dura or secondary to injury to vessels that accompany the cauda equina. This local bleeding rarely does harm to the patient, although patients with coagulation disturbances or who are receiving anticoagulants may develop continued bleeding with the development of spinal subdural or epidural hematomas, which may compress the cauda equina and produce permanent neurologic injury.

The most feared complication after lumbar puncture is brain herniation, which may occur in a patient with an elevation of ICP.^[1,6-8] In patients who undergo lumbar puncture, there is normally a mild, transient reduction of lumbar CSF pressure that is rapidly communicated throughout the subarachnoid space. In patients with bacterial meningitis and suspected severe intracranial hypertension or impending herniation, a 22- or 25-gauge spinal needle should be used, with careful observation for several hours after removal of CSF; monitoring and treatment of increased ICP may need to be considered (see later). In patients who have an intracranial space-occupying lesion, particularly one located in the posterior fossa, there is already a relative pressure gradient (with downward displacement of the cerebrum and brain stem) that can be increased by lumbar puncture and precipitate brain herniation.

Certain patients should undergo neuroimaging studies (i.e., computed tomography [CT] or magnetic resonance imaging [MRI]) before lumbar puncture if there is a suspicion that their neurologic presentation may be secondary to an intracranial mass lesion with accompanying mass effect. These include patients with the following characteristics: immunocompromised state (HIV infection or AIDS, receiving immunosuppressive therapy, or after transplantation), history of CNS disease (mass lesion, stroke, or focal infection), new-onset seizure, abnormal level of consciousness, papilledema, or focal neurologic deficit (including dilated, nonreactive pupil; abnormalities of ocular motility; abnormal visual fields; gaze palsy; or arm or leg drift).^[1,11,12] It has been suggested, however, that a normal CT scan does not always mean performance of a lumbar puncture is safe. Certain clinical signs of impending herniation, such as a deteriorating level of consciousness (particularly a Glasgow Coma Scale score ≤11), brain stem signs (including pupillary changes, posturing, or irregular respirations), or a very recent seizure, may be predictive of patients in whom lumbar puncture should be delayed.^[13]