The edition · Neurology
Steroids in herpes encephalitis: still no signal, either way
A pooled analysis finds no benefit and no clear harm from adjunctive corticosteroids in HSV encephalitis, on 209 patients in total. Plus exhaled carbon monoxide and Parkinson's risk, how the AChR antibody assay changes the answer, a carbamazepine recall, and the AAN's updated evidence on migraine prevention.
The edition in brief
Adjunctive corticosteroids in herpes simplex virus encephalitis have been used on the reasoning that inflammation, not just viral replication, drives the injury. A meta-analysis of four comparative studies — two randomised trials, two retrospective cohorts, 209 patients in all — found no difference in unfavourable global outcome (RR 1.00, 95% CI 0.68 to 1.47) or mortality (RR 0.92, 0.35 to 2.40). The intervals are wide enough to contain a worthwhile benefit and a real harm, so this is an absence of evidence rather than evidence of absence; the severe cerebral oedema case was never tested. In the China Kadoorie Biobank, regular smoking was associated with lower Parkinson's disease risk (HR 0.70, 0.62 to 0.79), and among never-smokers higher measured exhaled carbon monoxide was associated with lower risk in a graded way (3.0 to under 5.0 ppm: HR 0.62, 0.53 to 0.73; p for trend under 0.001), with no similar association for other neurodegenerative disease. It is observational and hypothesis-generating. The ADAM study compared acetylcholine receptor antibody assays in 327 patients with suspected myasthenia gravis: cell-based assays reached 97.7% specificity against 69.1% for ELISA, which produced false positives in 30.9% of non-myasthenic patients. The FDA has posted a Class II enforcement report for 200 mg carbamazepine tablets distributed by Golden State Medical Supply, for black specks arising from manufacturing deviations; it is a US distribution recall, not a safety warning about the drug. The AAN and American Headache Society systematic review of 217 randomised trials places galcanezumab and erenumab at high certainty for episodic migraine, fremanezumab, galcanezumab and onabotulinumtoxinA at high certainty for chronic migraine, and propranolol, topiramate and valproate at moderate certainty — with comparative evidence between active drugs still too weak to rank them.
Adjunctive corticosteroids in HSV encephalitis: no difference, on very little data
Do not add corticosteroids routinely in HSV encephalitis; the randomised evidence, all 209 patients of it, shows no benefit and cannot rule out harm.
Exhaled carbon monoxide tracks with lower Parkinson's risk in people who never smoked
Higher exhaled carbon monoxide was associated with lower Parkinson's risk in never-smokers — a mechanistic clue for the old smoking paradox, and not a reason to measure anything in clinic.
In suspected myasthenia, the assay behind the AChR result decides what it is worth
Cell-based assays for AChR antibodies are 97.7% specific against 69.1% for ELISA, so a positive ELISA in suspected myasthenia should be confirmed before it becomes the diagnosis.
FDA Class II recall of 200 mg carbamazepine tablets over visible specks
A Class II US recall of Golden State Medical Supply's 200 mg carbamazepine tablets for black specks — a quality defect, and the real clinical risk is a patient stopping the drug rather than replacing it.
An early negative CSF HSV PCR does not clear the patient
A negative CSF HSV PCR in the first 72 hours does not exclude herpes encephalitis — keep the aciclovir running and repeat the tap at day three to seven.
Migraine prevention: what the AAN evidence review will actually support
Galcanezumab and erenumab carry high-certainty evidence in episodic migraine and propranolol and topiramate moderate — but nothing here shows the newer drugs beat the older ones, so choose on comorbidity, pregnancy and cost.
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