It is a rare and acquired nerve disease considered to be a variant of the Guillain-Barré Syndrome. It is characterized by abnormal muscle coordination, ophthalmoplegia, and tendon areflexia. As with Guillain-Barré Syndrome, the symptoms may be preceded by a viral illness. Other clinical features include generalized muscle weakness and respiratory failure. The prognosis is good, with recovery beginning within 2 to 4 weeks and almost completed within 6 months. Residual neurologic deficits may occur, and relapses occur in less than 3% of individuals affected. The majority of individuals with Miller Fisher Syndrome have a unique antibody that characterizes the disorder.
It was first described in 1956 by Charles Miller Fisher, a Canadian neurologist.
It is a rare medical condition for which the exact incidence remains unknown. There are 223 cases reported in world literature. There is a male-to-female ratio of 2:1.
It is not a genetically inherited disorder. There are some evidence of an association with a viral infection.
Precipitating factors of the Miller Fisher Syndrome are an upper respiratory tract infection in the majority of cases, but also include infection, surgery, vaccination, or insect bite. Diplopia and ataxia are the first signs of development of the syndrome. The exact nature of the clinical entity is unclear, but the following three interpretations have been suggested: (1) the Miller Fisher Syndrome is a variant of the Guillain-Barré Syndrome; (2) the Miller Fisher Syndrome is a brain stem encephalitis without involvement of peripheral nerves; and (3) areflexia is caused by a lesion of the mesencephalon and the upper pontine reticular formation.
Ophthalmoplegia, unilateral or bilateral ptosis, and cerebellar ataxia with lower limb areflexia are required for diagnosis.
Other cranial nerves may be involved in the process, causing facial palsy, dysarthria, or dysphagia. The course of the disease has a duration between 3 weeks and 18 months with spontaneous remission. Rarely is the cerebellar ataxia or areflexia severe enough to cause major problems; the major impediment to these patients is their vision. Steroids, plasmapheresis, and immunoglobulin therapy have all been attempted to reduce the course of this illness.
Precautions before anesthesia
History and physical examination should reveal the extent of problems caused by the syndrome. Autonomic neuropathy and its consequent problems have not been reported in these patients. Cranial nerve impairment must be carefully documented before anesthesia. Eye examination by the anesthetist is worthwhile in order to have a baseline against which to gauge recovery.