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Lumbar punctures (LPs) are relatively safe procedures. However, some of the complications include:
Post-lumbar puncture headache
This is one of the most common complications after LP and occurs in 10-30% of patients receiving a LP. This is due to leakage of cerebrospinal fluid from the dura and traction on pain-sensitive structures. Patients with post-LP headache characteristically present with frontal or occipital headache within 12-24 hours after the procedure. Use of a higher gauge needle (i.e. smaller needle bore), orientation of the needle bevel parallel to the longitudinal fibers of the dura, and reinsertion of the stylet prior to needle removal have been shown to reduce the incidence of post-LP headache. For those with mild-moderate post-LP headache, these are usually self-limiting or improve with bed rest and analgesics. However, in those with severe prolonged headache, an epidural blood patch may be required.
Radicular symptoms and low back pain
Occasionally, patients complain of transient neuropathic pain in one leg during the procedure. However, sustained symptoms are rare.
Cerebral herniation
This is the most serious complication of a LP and occurs as a result of raised intracranial pressure, usually due to a significant intracranial mass lesion or cerebral oedema. Hence, cranial imaging is often performed prior to a LP. However, a CT brain in all patients prior to a LP may potentially delay treatment, e.g. in a patient with suspected acute bacterial meningitis. It is therefore currently advised that a CT scan prior to LP is not required unless patients has one of the following features: 1) altered mental status, 2) focal neurological signs, 3) papilledema, 4) recent seizures or 5) being immunocompromised.
Infection
With proper infection control measures, strict aseptic techniques with use of disinfectants and sterile equipment, meningitis is an uncommon complication of LP.
Bleeding
In the absence of an underlying significant bleeding diathesis, spinal hematoma resulting in spinal compromise is rare. LP is not recommended in those who have a severe thrombocytopenia (platelet count <50 x 109/L) or with an INR >1.4.