Case Report
Head drop after botox: Electrodiagnostic evaluation of iatrogenic botulinum toxicity

https://doi.org/10.1016/j.clineuro.2017.02.012Get rights and content

Highlights

  • Few reports of iatrogenic botulism (IB) include electrodiagnostic (EDX) confirmation.

  • Routine nerve conduction studies (NCS) can appear normal in cases of systemic IB.

  • Single fiber electromyography is informative by revealing prolonged mean jitter and frequent blocking.

  • It is important to perform prompt clinical and EDX evaluation of suspected IB.

Abstract

Background

Botulinum is a potent neurotoxin with increasing indications for neurologic disorders. While clinical benefit manifests primarily due to local actions at the neuromuscular junction, regional and systemic effects do occur. Rarely, systemic symptoms including weakness, dysarthria, dysphagia and other side effects occur as a result of iatrogenic botulinum neurotoxicity.

Case

A 72 year-old female with right leg dystonia developed head drop, bulbar and systemic weakness following right lower extremity botulinum toxin injection. Routine nerve conduction studies were normal. Repetitive stimulation of the spinal accessory nerve showed decrement; electromyography (EMG) demonstrated slightly small units with subtle signs of denervation, and single fiber EMG revealed increased jitter with blocking, all of which are consistent with systemic botulism.

Conclusion

This case highlights and reviews the important electrodiagnostic features of iatrogenic systemic botulinum neurotoxicity.

Introduction

Systemic weakness following botulinum neurotoxin injection is rare. Life-threatening cases of iatrogenic botulism have been reported following lethal doses of unlicensed preparations. In adults, iatrogenic botulism has been reported in hereditary spastic paraparesis, limb dystonia, hemiparesis, stroke, hyperhidrosis, and even following detrusor injection for neurogenic bladder [4], [5]. In the majority of reported cases, clinical criteria have established the diagnosis ([1], [6], [7], [8]). Few reports, however, have included electrodiagnostic (EDX) confirmation.

Section snippets

Report

A 72 year-old Caucasian female with Parkinson's disease (PD) and peripheral neuropathy presented for evaluation of right foot dystonia. She was initially managed with oral medications without improvement and subsequently underwent botulinum toxin type A (i.e. BOTOX® or onabotulinumtoxin A) injection twice at an outside facility (preparation and dose unknown). On presentation to our facility, examination revealed mild rigidity, bradykinesia, and severe gait disturbance with equinovalgus right

Discussion

Botulinum neurotoxin is an important therapy in many neurologic diseases, but local therapy can have distant effects. Underlying mechanisms of systemic neurotoxicity are unknown. Diffusion of botulinum toxin into adjacent muscles is well documented. Distant spread of neurotoxin may occur as a result of a shortened inter-dose interval, larger volume of fluid for injection, higher single injection doses, axonal transport, or other factors. Here we describe a case of iatrogenic botulism, and

Conclusion

Systemic botulinum neurotoxicity is a rare but recognized side effect of therapeutic botulinum toxin injections. Systemic botulinum neurotoxicity is a rare but recognized side effect of therapeutic botulinum toxin injections. EDX findings include decremental response on RNS and rare denervation potentials in addition to low amplitude and short duration motor unit morphology on EMG. Prompt clinical and electrodiagnostic evaluation is important. Findings suggest the pertinence of SFEMG to confirm

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