Miller Fisher syndrome

Miller Fisher syndrome is a regional variant of Guillain–Barré syndrome and characterized by cranial nerve involvement and the triad of ataxia, areflexia, and ophthalmoplegia. They are now believed to represent, along with a number of other entities, different clinical manifestations of a similar underlying autoimmune disorder, anti-GQ1b IgG antibody syndrome. 

Clinical presentation

Patients who develop Miller Fisher syndrome usually have a rapid onset of ataxia, areflexia, and ophthalmoplegia, which usually follows a viral illness in the preceding 5-10 days . Ophthalmoplegia (initially upgaze, then lateral gaze and then downgaze) and ataxia usually precede areflexia .

Areflexia of the limbs only occasionally is associated with weakness .

Electrophysiological findings most commonly include reduced sensory nerve action potentials and absent H reflexes .

Pathology

Miller Fisher syndrome is considered to be a peripheral neuropathy, however involvement of the central nervous system has also been reported (somewhat controversially), including lesions within the posterior columns of the spinal cord and in the brainstem .

Anti-GQ1b antibodies are present in most (~80-90%) of cases .

Radiographic features

MRI

Although MRI is usually used to investigate patients with these symptoms, there can be no abnormalities .

Multiple cranial nerves enhancement is reported, as it is with Guillain-Barré syndrome .

Treatment and prognosis

Although most cases of Miller Fisher syndrome have a good prognosis, occasional cases with permanent neurological disability are encountered. Fatal progression has also been described but is uncommon (<5%) .

Generally, recovery begins a few weeks after symptom onset and is usually complete by 6 months .

Treatment with immunomodulatory therapies is controversial .

History and etymology

It is named after Charles Miller Fisher (1913-2012) a renowned Canadian neurologist, who first described the condition in 1956 .

Differential diagnosis

Clinically the differential includes primarily the other anti-GQ1b IgG antibody-associated conditions.