The startle reflex is a motor response that originates in the lower brainstem.1 Abnormal symptomatic startle can be secondary to lesions in the startle pathway, involving brainstem and spinal cord.2 A 56-year-old woman developed an acute demyelinating lesion of unknown origin in medulla oblongata (figure, A–D), causing dizziness and bilateral sensory impairment with paresthesias. No tongue weakness, myoclonus, or symptoms of restless leg syndrome were present. When the symptoms remitted, she developed a severe symptomatic startle response. Pathologic startle was elicited by sensory—especially acoustic—stimuli (video, see the Neurology Web site at www.neurology.org). Startle was bilateral and the EMG burst duration, recorded with surface deltoid EMG, ranged from 500 to 1,200 msec. Startle was not responsive to pharmacologic treatment (benzodiazepines and carbamazepine) and was disabling for the patient.
Figure. MRI scans. An area of abnormal signal, probably of demyelinating origin, is evident in the upper medulla and pons. No other signal abnormalities are evident within the CNS; in particular, the cervical cord is spared (B).
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Additional material related to this article can be found on the Neurology Web site. Go to www.neurology.org and scroll down the Table of Contents for the February 6 issue to find the title link for this article.
Disclosure: The authors report no conflicts of interest.
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