Genetic screening for human leukocyte antigen alleles prior to carbamazepine treatment.

We describe a 28-year-old Malaysian Australian man of Han Chinese descent with toxic epidermal necrolysis (TEN), occurring 2 weeks after commencing carbamazepine. He was subsequently found to be positive for human leukocyte antigen (HLA)-B*1502. Carbamazepine-induced Stevens-Johnson syndrome/TEN is strongly associated with the HLA-B*1502 allele, which is highly prevalent in Han Chinese, Malay, Thai and Indian populations. Prospective screening for the allele may prevent this cutaneous adverse drug reaction from occurring, but many neurologists and other medical practitioners are still unaware of the medico-legal risks of prescribing carbamazepine in susceptible populations and the availability of HLA-B*1502 testing. Performing HLA-B*1502 genotyping and avoiding carbamazepine in at-risk individuals has been proven to decrease incidences of drug-induced TEN. This test is widely available at most large pathology services in Australia, with results available within 2 weeks. The recommendation by regulatory bodies should be strengthened to ensure that the broad medical community is made more aware of this pertinent issue.

Spontaneous low pressure headache - a review and illustrative patient.

Low pressure headache typically occurs as a complication of dural puncture. "Spontaneous" low pressure headache is a relatively rare but under-recognised cause of intractable headache. Clinical suspicion of this condition warrants imaging of the brain to confirm the diagnosis; spinal imaging may be needed to identify the site of the leak. Epidural blood patching may be necessary to seal the leak - CT fluoroscopy may be helpful in delivering the patch directly to the site of the leak. Surgical intervention may be required in intractable cases. We describe a patient with spontaneous intracranial hypotension and review the clinical and radiological features of this syndrome.

What lies beneath the tent? JC-virus cerebellar granule cell neuronopathy complicating sarcoidosis.

A 49-year-old, HIV-negative woman with sarcoidosis presented with a subacute unilateral cerebellar syndrome. A brain MRI revealed a hyperintense lesion without mass effect in the left cerebellar hemisphere, but no pathology above the tentorium. Steroid therapy for presumed neurosarcoidosis was ineffective and the patient deteriorated progressively. Cerebellar biopsy showed abnormal granule cells and demyelination. Immunocytochemistry confirmed the diagnosis of progressive multifocal leucoencephalopathy (PML) with JC (John Cunningham) virus granule cell neuronopathy. The patient succumbed to progressive brainstem dysfunction despite treatment with cidofovir. Although rare, PML should be considered in all patients with impaired cell-mediated immunity and unexplained neurological dysfunction, even in the absence of HIV infection.