Ophthalmoplegia and Slurred Speech in an Intravenous Drug User

A 35-year-old unemployed man presented to Accident and Emergency with a three-day history of progressive diplopia and a one-day history of slurred speech. There was no history of fever, paraesthesiae, dysphagia, or respiratory diffi culty. He admitted drug abuse including " muscling " (intramuscular injection of heroin). On examination, the patient was well, ambulant, alert, and orientated. Vital signs were normal and oxygen saturation was 97% (room air). There were injection sites in both arms but no infected wounds. There were no cardiac murmurs. The rest of the general examination was normal. Visual fi elds were full and fundi normal. Bilateral partial ptosis and complete bilateral ophthalmoplegia were obvious. Pupils were dilated and poorly responsive to light, without an afferent pupillary defect. Facial muscle power was normal. There was dysarthria with absent palatal movements but a normal gag refl ex. No other abnormal neurology was present; limb power was normal with preserved deep tendon refl exes and no ataxia. The gait was normal. Full blood count, and renal and liver function tests were within normal limits. C-reactive protein was 3 mg/l (normal <10 mg/l). Blood cultures and serum were sent for microbiological testing. Chest X ray and electrocardiogram were normal. The patient was admitted for observation. What Is the Likely Diagnosis? Over a period of three days this patient has developed symmetrical paralysis of the ocular and oropharyngeal muscles without long-tract signs or sensory defi cit. Is the disease central or peripheral in origin? A central cause is diffi cult to envisage since it would involve several cranial nerve nuclei yet spare other structures such as corticospinal tracts. Peripheral causes may act at the level of motor nerves, neuromuscular junction, or muscle. A primary muscular cause is unlikely because of the rapid onset of symptoms. Motor neuropathies may be acute, e.g., a cranial variant of Guillain-Barré syndrome; however features such as antecedent illness, paraesthesiae, and loss of refl exes would be expected. Myasthenia gravis is a common neuromuscular disorder that may present relatively acutely. However, pupillary dilatation is not observed because antibodies that mediate this disease are specifi c for nicotinic acetylcholine receptors, thereby sparing the parasympathetic nervous system. Furthermore, total ophthalmoplegia would be very unusual. The clinical syndrome is typical of wound botulism. Botulinum toxin acts pre-synaptically at all peripheral cholinergic synapses, blocking neuromuscular junctions as well as parasympathetic and sympathetic pathways. Cranial nerves are affected before descending weakness …