Transient tonic pupils in botulism type B

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.

Contribution of Single-Fiber Evaluation on Monitoring Outcomes Following Injection of Botulinum Toxin-A: A Narrative Review of the Literature

Botulinum toxin-A (BoNT-A) blocks acetylcholine release at the neuromuscular junction (NMJ) and is widely used for neuromuscular disorders (involuntary spasms, dystonic disorders and spasticity). However, its therapeutic effects are usually measured by clinical scales of questionable validity. Single-fiber electromyography (SFEMG) is a sensitive, validated diagnostic technique for NMJ impairment such as myasthenia. The jitter parameter (µs) represents the variability of interpotential intervals of two muscle fibers from the same motor unit. This narrative review reports SFEMG use in BoNT-A treatment. Twenty-four articles were selected from 175 eligible articles searched in Medline/Pubmed and Cochrane Library from their creation until May 2020. The results showed that jitter is sensitive to early NMJ modifications following BoNT-A injection, with an increase in the early days’ post-injection and a peak between Day 15 and 30, when symptoms diminish or disappear. The reappearance of symptoms accompanies a tendency for a decrease in jitter, but always precedes its normalization, either delayed or nonexistent. Increased jitter is observed in distant muscles from the injection site. No dose effect relationship was demonstrated. SFEMG could help physicians in their therapeutic evaluation according to the pathology considered. More data are needed to consider jitter as a predictor of BoNT-A clinical efficacy.

Congenital Mydriasis: Diagnostic Challenge in a Case with Accompanying Neurologic Symptoms

A 34-year-old woman was hospitalised with acute onset nausea, vomiting, ataxia, nystagmus, blurred vision, and bilateral mydriasis. Toxicologic investigations and serologic tests for infectious aetiologies were negative. Demyelinating disease was suspected based on magnetic resonance imaging (MRI) findings but there were no lesions at the midbrain explaining bilateral mydriasis. Direct light, consensual light, and near responses for pupil were all negative. Biomicroscopic examination of the iris did not show any sphincter damage or tonic movements. Pupils didn't respond to pilocarpine (0.1% and 2%) and remained unresponsive during the follow-up period. Congenital mydriasis was diagnosed because old photographs revealed that pupils were dilated previously.

Disorders of the pupil

Pupil size is determined by the interaction of the parasympathetic and the sympathetic nervous system. The parasympathetic system conducts the light reaction with its major center in the dorsal midbrain. The sympathetic nervous system acts either directly on the dilator muscle (peripherally) or centrally by inhibiting the Edinger-Westphal nucleus. Psychosensory reactions are transmitted via the sympathetic system. The afferent input of the light reflex system in humans is characteristically wired, allowing a detailed analysis of a lesion of the afferent input. Even in humans a subgroup of ganglion cells containing melansopsin plays an important role as a light sensor for the pupillary system. To diagnose normal pupillary function, pupils need to be isocoric and react bilaterally equally to light. Anisocoria indicates a problem of the efferent pupillary pathway. Pupillary disorders may involve the afferent pathways (relative afferent pupillary defect) or the efferent pathways. Physiological anisocoria is a harmless condition that has to be distinguished from Horner's syndrome. In this case pharmacological testing with cocaine eye-drops is helpful. Disorders of the parasympathetic system will impair the light response. They include dorsal midbrain syndrome, third-nerve palsy, and tonic pupil. Tonic pupils are mainly idiopathic and do not need imaging. Disorders of the iris, including application of cholinergic agents, need also to be considered in impaired pupillary light reaction.

Infant Botulism and Raised Intraocular Pressure

Infant botulism is an exceedingly rare disease. Because confirmatory laboratory testing is not available for several days after time of presentation, infant botulism remains a clinical diagnosis. The authors demonstrate how raised intraocular pressure may provide an additional clinical clue to making the diagnosis.

Reversible posterior leukoencephalopathy and Adie's pupil after measles vaccination

Reversible posterior leukoencephalopathy syndrome is an increasingly recognized disorder with typical radiologic findings of bilateral gray- and white-matter abnormalities in the posterior regions of the cerebral hemispheres. The majority of patients with reversible posterior leukoencephalopathy syndrome are adults, and it is rare in children. Previously reported associations of reversible posterior leukoencephalopathy syndrome include hypertension, vasculitis, nephrotic syndrome, severe hypercalcemia, hemolytic uremic syndrome, eclampsia, renal failure, and use of immunosuppressive drugs. Adie's pupil is described as the presence of a large unilateral or bilateral tonic pupil related to virus infections or trauma. In this article, we describe a case of reversible posterior leukoencephalopathy and Adie's pupil association that occurred after measles vaccination. To our knowledge, this association has not been reported.

Ophthalmic Manifestations in 18 Patients with Botulism Diagnosed in Porto, Portugal Between 1998 and 2003

BACKGROUND

Botulism is a rare but potentially lethal disease in which ophthalmic signs and symptoms are among the very earliest manifestations. The aim of this study was to investigate the epidemiological and clinical features of botulism-infected patients admitted to a general hospital in Porto, Portugal.

METHODS

We performed a retrospective chart review of all botulism patients admitted to São João Hospital between January 1998 and January 2003. We excerpted data on epidemiology, ophthalmic and non-ophthalmic manifestations, and treatment.

RESULTS

We identified 18 patients in nine registered outbreaks. In two patients (11%), ophthalmic manifestations preceded systemic manifestations; in six patients (33%), ophthalmic and systemic manifestations occurred simultaneously; in ten patients (56%), systemic manifestations occurred first. Ophthalmologists had examined only seven patients and made the correct diagnosis in five. The most common ocular symptoms were blurred near vision (100%), blurred distant vision (94%), and diplopia (44%). Accommodation impairment was documented in all seven patients examined by ophthalmologists.

CONCLUSIONS

Ophthalmic manifestations were among the earliest and most prominent manifestations of botulism in this series, as in earlier reports. The diagnosis should be suspected when impaired accommodation and gastrointestinal symptoms occur together.

Clostridium botulinum and the ophthalmologist: a review of botulism, including biological warfare ramifications of botulinum toxin

The anaerobic bacterium Clostridium botulinum causes disease by elaborating an extremely potent neurotoxin that inhibits release of acetylcholine at presynaptic nerve endings, thereby resulting in a descending flaccid paralysis and autonomic nervous system dysfunction. Possible ophthalmological effects of this neurotoxin are many and typically constitute the earliest manifestations of botulism. This review summarizes the medical literature on botulism with regard to historical perspective, epidemiology, clinical manifestations, and treatment. Ophthalmological findings of botulism are tabulated and their frequencies are provided. Finally, the bioterrorism/biologic warfare ramifications of botulinum toxin are briefly discussed.

Physiology, assessment, and disorders of the pupil

Proper examination of the pupil provides an objective measure of the integrity of the pregeniculate afferent visual pathway and allows assessment of sympathetic and parasympathetic innervation to the eye. Infrared videography and pupillography are increasingly used to study the dynamic behavior of the pupil in common disorders, such as Horner's syndrome and tonic pupil.