Startle Myoclonus Induced by Lyme Neuroborreliosis

Julia Schoof; Christian Kluge; Hans-Jochen Heinze; Imke Galazky

Disclosures

J Med Case Reports. 2013;7(124) 

In This Article

Abstract and Introduction

Abstract

Introduction: The normal startle response is a form of physiological myoclonus. Its anatomic origin is probably the brain stem. Pathologic startles are defined as reproducible exaggerated startle responses to trivial and not surprising stimuli. Symptomatic forms of an exaggerated startle response can be due to a variety of brain stem disorders. We have, however, found scant data about an exaggerated startle reflex induced by Lyme neuroborreliosis. We therefore report the case of a patient with this unusual presentation.

Case presentation: A 69-year old Caucasian man presented with a two-week history of a pronounced startle myoclonus, as well as a four-week history of double vision, gait disturbance and severe lancinating pain in his upper thoracic region. Neurological examination showed an excessive startle reaction of his upper trunk evoked by visual and tactile stimulation, a positive sign of Lhermitte, mild right-sided palsy of his sixth and seventh cranial nerve, moderate dysarthria, very brisk deep tendon reflexes, pallhypesthesia of his legs, and an atactic gait disturbance. A diagnosis of a Lyme neuroborreliosis was confirmed by cerebrospinal fluid examination. Under intravenous treatment with ceftriaxone, our patient improved considerably with complete remission in a follow-up at two months.

Conclusions: This case illustrates the chameleon role that neuroborreliosis likes to play: although the wide spectrum of different symptoms that neuroborreliosis can present with has been described, to the best of our knowledge this is the first case report about a symptomatic form of a pathologic startle response as the predominating sign of Lyme neuroborreliosis.

Introduction

The normal startle response is a form of physiological myoclonus. Its clinical presentation usually consists of an involuntary jerky movement (with blink, contortion of the face, flexion of neck and trunk, and abduction and flexion of the arms) evoked by a sudden and unexpected acoustic stimulus. Its anatomic origin is probably the brain stem.[1] Pathologic startles are defined as reproducible exaggerated startle responses to trivial and not surprising stimuli.[2] The most common form of an exaggerated startle response is hereditary hyperekplexia, which is genetically characterized by defects in different gene families involved in glycine neurotransmission.[3] Symptomatic forms of an exaggerated startle response are less frequent and can be due to a variety of brain stem disorders, tetanus, strychnine intoxication or stiff-man syndrome.[1,2,4] We have, however, found scant data about an exaggerated startle reflex induced by Lyme neuroborreliosis.[5] We therefore report the case of a patient with this unusual presentation.

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