Headache is what we commonly think of as a sequela of dural puncture. Other adverse consequences of dural puncture include ocular and auditory disturbance. Ocular abnormalities are due to cranial nerve palsy, typically involving the sixth nerve cranial (abducens nerve), and uncommonly involving the third and fourth cranial nerves.
Dr. Jennifer E. Hofer, Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois, and Dr. Barbara M. Scavone, also from the Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois, summarize the incidence, time course, presentation, pathophysiology, risk factors, prevention, and treatment of cranial nerve six palsy after dural puncture. Their review is contained in the article titled “Cranial Nerve VI Palsy After Dural-Arachnoid Puncture,” published in this month’s issue of Anesthesia & Analgesia.
Headache usually precedes ocular involvement. Though other neurologic and ophthalmic abnormalities should be considered, if an isolated ocular deficit preceded by headache is seen within 3 weeks of dural puncture, the abnormality is likely a consequence of dural puncture. Patient complaints include blurred or double vision, sensitivity to light, and trouble focusing or reading. On physical exam, there is impaired ocular abduction, though findings may be subtle. In most cases the palsy is unilateral. Diplopia may persist for months. However, by 8 months the majority of patients (89%) have recovered.
The basis for palsy is presumed to be due to loss of CSF that results in intracranial hypotension, with caudal displacement of the brainstem causing cranial nerve traction. The position of cranial nerve VI in the brain makes it susceptible to preferential damage. Neural ischemia may result in focal segmental demyelination (neuropraxia) and/or axonal interruption. The length of time for recovery is a function of the time needed for myelin regeneration.
Since headache precedes cranial nerve VI palsy, and both are related to intracranial hypotension, they may share similar risk factors. Postdural puncture headache is most likely in younger individuals, and in women, after vaginal as opposed to cesarean section. Use of small-gauge and non-cutting needles decreases the incidence of headache. Though epidural blood patch usually provides relief of headache, it does not reliably reverse cranial nerve VI palsy, particularly if neural demyelination has already occurred.
This is a nice review of an important topic. Clinicians should be aware that headache is not the only potential complication of dural puncture.