Symptoms of Fisher syndrome can lead doctors to also diagnose asymptomatic Lambert‐Eaton myasthenic syndrome (LEMS), according to a case study in Japan.
The report, “A case presenting electrophysiological and immunological characteristics of Fisher syndrome and Lambert‐Eaton myasthenic syndrome,” was published in the journal Muscle & Nerve.
LEMS mainly affects muscles in the lower limbs and is characterized by muscle weakness in the legs that spreads to the arms and shoulders. People with LEMS often experience weakening eye muscles, leading to double vision and drooping eyelids.
Fisher syndrome — also called Miller Fisher syndrome — is a rare disorder characterized by abnormal muscle coordination, paralysis of the eye muscles, and the absence of tendon reflexes.
In the study, researchers documented the case of a 70-year-old woman who came to a hospital in Sapporo, Japan, with numbness in both hands, double vision, and unsteadiness over the previous two weeks.
She had no recent history of infection or other illness, and had normal family and medical histories.
She had a drooping left eyelid, with her pupils being evenly dilated on both sides. She also experienced weakness in the muscles surrounding her eyes and in her limbs, required a walker, and had an abnormal gait known as truncal ataxia. Her tendon reflexes were initially absent but improved after brief exercise.
Despite no noticeable electromyography abnormalities found in her hands and forearms, nerve conduction tests revealed low compound muscle action potential (CMAP), a measure of how well nerves interact with muscles. Other tests revealed abnormal neuromuscular transmission, meaning alterations in the nerves’ ability to control muscle movement.
Lab tests revealed the presence of antibodies against GQ1b and P/Q-type voltage-gated calcium channels (VGCC). Notably, VGCCs are found at the connection between nerves and muscles, where they work to induce muscle contraction.
Anti-GQ1b antibodies are typical of Fisher syndrome. In turn, anti-P/Q-type VGCC antibodies, which cause LEMS, are found in up to 90% of LEMS patients.
The woman in the report improved spontaneously. She walked independently in six weeks, regained normal movement of the muscles surrounding her eyes in six months, and no longer had anti-GQ1b antibodies. The results of her sensory nerve tests returned to normal. She continued to show low CMAP and loss of tendon reflexes at rest.
According to the scientists, this case exhibited a typical pattern of Fisher syndrome, except that post-exercise reflex improvement had not been reported in patients with the syndrome. Mild weakness has been recognized in approximately 20% to 25% of these patients.
The woman in the case study had a reflex pattern and the presence of anti-P/Q-type VGCC antibodies, which suggested a diagnosis of asymptomatic LEMS. Although weakness in the legs is a common early LEMS symptom, the woman’s mild and transient weakness in those muscles did not meet LEMS diagnostic criteria, the scientists said.
“Based on the clinical course, this patient was diagnosed as typical [Fisher syndrome] concurrent with asymptomatic LEMS,” the scientists wrote.
The antibody findings are unlikely to be false positives, as they correspond to the woman’s symptoms and the results of electrical activity tests in nerves, they added.
The researchers plan to follow up every six months to reconfirm evidence of LEMS and to check for any developments in her symptoms.
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