Benign food-borne type B botulism presenting as unilateral internal ophthalmoplegia: a case report

BACKGROUND

Food-borne botulism is a rare neuromuscular junction disorder due to the effect of toxins released from Clostridium botulinum ingested by eating improperly stored food. Its classic manifestation is a rapidly evolving descending symmetrical flaccid paralysis with dysautonomia.

CASE PRESENTATION

We have described a case of type B food-borne botulism with a benign clinical course characterized by an initially unilateral tonic mydriatic pupil. An extensive neurophysiological evaluation inclusive of pilocarpine eye drop(s) test, facial and limbs nerve stimulation and sudomotor tests, was decisively leading the diagnostic process.

CONCLUSIONS

The importance of what has been described here lies in underlining that it is always advisable to consider food-borne botulinum intoxication, even in the case of unilateral/asymmetrical internal ophthalmoplegia without generalized progressive involvement of the voluntary muscles.

Klinische Neurophysiologie auf der pädiatrischen Intensivstation

Auf pädiatrischen Intensivstationen kommt es häufig zum Einsatz neurophysiologischer Untersuchungsmethoden. Bei akuten Enzephalopathien oder in Situationen, in denen ein hohes Risiko für epileptische Anfälle besteht, werden verschiedene Varianten des EEGs verwendet. Bei Hinweisen auf neuromuskuläre Erkrankungen sind die Neurographie, die evozierten Potentiale, und die Elektromyographie die entscheidenden diagnostischen Methoden. Im Falle erworbener Hirnschädigungen wie z. B. nach Reanimationsereignissen oder bei Schädel-Hirn-Traumata können sowohl das EEG, als auch die evozierten Potentiale zur Prognoseabschätzung verwendet werden. Die Umstände auf der Intensivstation erschweren bei all diesen Methoden die Durchführung und die Interpretation. Viele Patienten werden mit Medikamenten behandelt, die die Untersuchungsergebnisse beeinflussen (insbesondere Sedativa und Muskelrelaxantien). Elektronische Geräte, z. B. für die Beatmung der Patienten, können zum Auftreten deutlicher Artefakte bei den neurophysiologischen Untersuchungen führen. Im vorliegenden Artikel werden die Einsatzbereiche neurophysiologischer Methoden auf pädiatrischen Intensivstationen beschrieben und auf Details bei der Anwendung eingegangen.

Neurophysiological patterns of acute and post-acute foodborne botulism

INTRODUCTION/AIMS

Neurophysiological patterns in patients with foodborne botulism are rarely described after the acute phase. We report data from a large Italian outbreak of botulism, with patients evaluated at different timepoints after poisoning.

METHODS

Eighteen male patients (mean age 47 ± 8.4 y) underwent 22 clinical and neurophysiological evaluations (4 patients were re-evaluated). The resting compound muscle action potential (CMAP) amplitude, postexercise CMAP amplitude, CMAP change after high-frequency (50 Hz) repetitive nerve stimulation (HFRNS), and motor unit action potentials (MUAPs) were assessed in the acute (4-8 days after poisoning; 5 patients), early post-acute (32-39 days after poisoning; 5 patients), and late post-acute (66-80 days after poisoning; 12 patients) phases.

RESULTS

In the acute, early post-acute, and late post-acute phases, respectively, reduced CMAP amplitudes were found in 100%, 20%, and 17% of patients; abnormal postexercise CMAP facilitation was observed in 100%, 40%, and 0% of patients; and pathological incremental responses to HFRNS were found in 80%, 50%, and 8% of patients. Baseline CMAP amplitudes, postexercise CMAP facilitation, and CMAP increases in response to HFRNS differed significantly between the acute and post-acute phases. Small MUAPs were found in 100% of patients in the acute and early post-acute phases and in 50% of patients in the late post-acute phase.

DISCUSSION

The neurophysiological findings of foodborne botulism vary considerably according to the evaluation time point. In the post-acute phase, different neurophysiological techniques must be applied to support a diagnosis of botulism.

Neuromuscular junction disorders

Disorders of the neuromuscular junction, such as myasthenia gravis and Lambert-Eaton myasthenic syndrome, constitute an important and treatable class of diseases. Both disorders are typically caused by an immunologically mediated attack on discrete components of the neuromuscular junction, compromise the efficacy of neurotransmitter transmission, and produce clinically distinct syndromes of fatigable muscle weakness. Although the history, clinical examination, and routine antibody testing can be diagnostic in many cases, specialized neurophysiological tests, such as repetitive nerve stimulation and single-fiber electromyography, are essential tools in the diagnostic evaluation of patients with more complicated or atypical conditions. In this review, we introduce primary disorders of the neuromuscular junction, and discuss the salient clinical and laboratory workup appropriate for recognizing these disorders, and the typical findings seen on electrodiagnostic testing with repetitive nerve stimulation and single-fiber electromyography.

Contralateral weakness following botulinum toxin for poststroke spasticity

INTRODUCTION

We describe 2 patients who received botulinum toxin A (BoNT) for poststroke spasticity and developed contralateral limb weakness.

METHODS

Both patients received high doses of BoNT with large dilution volumes and injection in the proximal upper extremity muscles, and developed weakness of the contralateral upper limb. These patients then underwent electrodiagnostic testing of the affected limb.

RESULTS

Repetitive nerve stimulation of the axillary and spinal accessory nerves revealed decrements of 23% and 16%, respectively. EMG revealed abnormal spontaneous activity and small polyphasic motor unit potentials with reduced recruitment. These findings indicated blockade of the neuromuscular junction. Both patients improved.

CONCLUSIONS

Isolated weakness of the contralateral limb after BoNT injection for poststroke spasticity suggests diffusion of toxin through tissue planes from proximal upper extremity muscles, across the midline, to contralateral muscles. High doses of botulinum toxin, high dilution volumes, and injection of proximal upper extremity muscles appear to be risk factors for this adverse effect.

Wound botulism in drug users: a still underestimated diagnosis

Wound botulism is a rare infectious disease that is becoming a frequent complication of parental drug use. Diagnosis is often difficult and based on clinical suspicion. We report the first Italian case of wound botulism due to intramuscular heroin injection in a 48-year-old man with an acute onset of slurred speech and dysphagia. The most considerable finding of electrophysiological study was the reduction in amplitude of compound muscle action potential which should be considered a useful initial electrodiagnostic sign in the clinical context of botulism. Alerting clinicians to botulism is crucial for a rapid diagnosis and appropriate treatment and thus decreasing mortality and complications.