Makindo Medical Notes

Miller Fisher Syndrome (MFS) is a rare variant of Guillain-Barré Syndrome (GBS) associated with the presence of anti-GQ1b antibodies, primarily affecting the eyes and ocular muscles.

About

• Miller Fisher Syndrome (MFS): A rare variant of Guillain-Barré Syndrome, accounting for approximately 5% of GBS cases.
• MFS is characterized by a distinct clinical triad of ophthalmoplegia, ataxia, and areflexia, without the generalized weakness typically seen in other forms of GBS.

Clinical Features

• Ophthalmoplegia: Paralysis or weakness of the ocular muscles is usually the first sign, leading to double vision (diplopia) or difficulty moving the eyes.
• Ataxia: Unsteady gait and difficulty with coordination, often without significant weakness.
• Areflexia: Loss of deep tendon reflexes is a hallmark feature, but motor strength is usually preserved.
• MFS may also begin with cranial nerve involvement, leading to facial weakness, but without widespread muscle weakness, distinguishing it from classic GBS.

Differential Diagnosis

• Myasthenia Gravis: Both can present with ocular symptoms, but MG typically has fluctuating muscle weakness and does not have areflexia.
• Botulism: Ocular muscle involvement can occur, but botulism often involves descending paralysis and autonomic dysfunction.
• Diphtheria: Can cause cranial nerve palsies, but is usually accompanied by other systemic signs of infection.
• Tick paralysis: Rare, but can cause ascending paralysis; tick bite history and Lyme disease association are clues.
• Sarcoidosis: Can involve cranial nerves and present with neuropathy, but other systemic signs are often present.

Investigations

• Anti-GQ1b antibodies: Present in about 90% of patients with Miller Fisher Syndrome, making this a key diagnostic marker.
• CSF analysis: Typically shows albuminocytologic dissociation (increased protein with normal white cell count), similar to GBS.
• Electromyography (EMG) and nerve conduction studies: May show evidence of demyelination, though typically less pronounced than in classic GBS.

Management

• Intravenous immunoglobulin (IVIg): A first-line treatment option for MFS, similar to GBS.
• Plasmapheresis: Can also be considered as an alternative or adjunct treatment to IVIg.
• Supportive care: Symptomatic treatment, including physical therapy and close monitoring of respiratory function if there is a risk of progression to more generalized GBS.
• Prognosis: The prognosis for Miller Fisher Syndrome is generally good, with most patients achieving full recovery within weeks to months.