Prolonged duration of the distal compound muscle action potential (DCMAP) ("DCMAP dispersion") is useful in the electrodiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) with good specificity in distinguishing CIDP from amyotrophic lateral sclerosis (ALS) and diabetic polyneuropathy, but its role in the electrodiagnosis of acute inflammatory demyelinating polyneuropathy (AIDP) is unclear. This study addresses this issue by determining the optimal cutoff for DCMAP duration using receiver operating characteristic (ROC) analysis in 207 motor nerves from 53 clinically defined AIDP patients compared to 148 motor nerves from 55 ALS patients. We also determined whether the presence of DCMAP dispersion improves the sensitivity of four of the most sensitive published sets of electrodiagnostic criteria for AIDP. Using the ROC-derived optimal DCMAP duration cutoff of 8.5 ms, DCMAP dispersion was found in at least one motor nerve in 66% of subjects with AIDP compared to 9% of subjects with ALS. DCMAP dispersion improved the sensitivity of the four tested criteria sets to 76%-87% from 43%-77%. Moreover, of 13 AIDP patients who met none of the four published criteria sets, 5 (38%) had at least one dispersed DCMAP. These findings indicate that the presence of DCMAP dispersion adds electrodiagnostic sensitivity to the currently published criteria sets, while maintaining reasonably high specificity against a prototypical disorder of the primary motor neuron with axon loss.

Short-lasting unilateral neuralgiform headache attacks with conjuctival injection and tearing (SUNCT) syndrome is an uncommon headache syndrome. It is usually resistant to treatment. We describe a patient who responded successfully to the anticonvulsant lamotrigine, but not other anticonvulsants commonly used in the treatment of migraine and other cephalgias.

A 68-year-old male patient presented to the neurology clinic with tremor, lightheadedness, and a history of syncope. Exam showed mild Parkinsonism. Neuroimaging revealed symmetric lesions of the globus pallidus (the eye-of-the-tiger sign) concerning for neurodegeneration with brain iron accumulation (NBIA). Genetic panel for NBIA was ordered, specifically pantothenate kinase-associated neurodegeneration (PKAN), including pantothenate kinase 2 (PanK2) - the genetic marker for the pantothenate kinase enzyme.