title: Neck atonia with a focal stimulation-induced seizure arising from the SMA: pathophysiological considerations.
abstract: A 28-year-old patient with pharmacoresistant non-lesional right frontal epilepsy underwent extra-operative intracranial EEG recordings and electrical cortical stimulation (ECS) to map eloquent cortex. Right supplementary motor area (SMA) ECS induced a brief seizure with habitual symptoms involving neck tingling followed by asymmetric tonic posturing. An additional feature was neck atonia. During atonia and sensory aura, discharges were seen in the mesial frontal electrodes and precentral gyrus. Besides motor signs, atonia, although rare and not described in the neck muscles, and sensations have been reported with SMA stimulation. The mechanisms underlying neck atonia in seizures arising from the SMA can be explained by supplementary negative motor area (SNMA) - though this was not mapped in electrodes overlying the ictal onset zone in our patient - or primary sensorimotor cortex activation through rapid propagation. Given the broad spectrum of signs elicited by SMA stimulation and rapid spread of seizures arising from the SMA, caution should be taken to not diagnose these as non-epileptic, as had previously occurred in this patient.
authors: Institute of Neurology, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK. skovac@ion.ucl.ac.uk
authors: Stjepana
authors: S
authors: Kovac
authors: Parashkev
authors: P
authors: Nachev
authors: Roman
authors: R
authors: Rodionov
authors: Catherine
authors: C
authors: Scott
authors: Andrew W
authors: AW
authors: McEvoy
authors: Nathan
authors: N
authors: Toms
authors: Tim
authors: T
authors: Wehner
authors: John S
authors: JS
authors: Duncan
authors: Beate
authors: B
authors: Diehl
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation / Q000009:adverse effects*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009044:Motor Cortex / Q000503:physiopathology*; D009334:Neck Muscles / Q000502:physiology*; D012640:Seizures / Q000473:pathology* / Q000628:therapy*