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Acute inflammatory demyelinating polyneuropathy (AIDP) is a relatively uncommon disease with a worldwide incidence of 0.75-2.0 cases per 100,000 population . Its diagnostic criteria have been well-defined . At times, AIDP is associated with unusual presentation of which Fisher's Syndrome  is the most aberrant one characterized by ophthalmoplegia, ataxia and areflexia without significant motor weakness or sensory symptoms and having a benign course with complete recovery. Detection of an enhancing CT lesion in brain stem in some cases suggested central rather than peripheral lesion as the cause. The present report aims to highlight the rarity as well the controversies about the status of this clinical entity.
SSP, a 20-years-old soldier presented with an acute neurological illness manifesting in the first week of July ’96 with diplopia, difficulty in swallowing with nasal regurgitation of fluids and unsteadiness on walking. It was preceded a fortnight earlier by a transient febrile illness and loose motions lasting for 4-5 days. While his dysphagia improved, his other symptoms progressed rapidly leading to restriction of eyeball movement in all directions and a bed-ridden state. There was no history of tinnitus, vertigo, dysarthria, seizures, loss of consciousness, root pains or sphincteric disturbances. He denied recent vaccination or exposure to toxins.
At admission, he was afebrile with a BP of 160/100 mm of Hg and pulse of 72/min. There was no respiratory distress, icterus, clubbing or lymphadenopathy. Neurological examination revealed external ophthalmoplegia with fixed eyeballs. Pupils and other cranial nerves were normal. He had grade 4/5 motor weakness with areflexia. The plantar response was flexor bilaterally. He had marked incoordination and ataxia due to which he was not able to sit or stand. Examination of the fundus and other systems was normal.
Investigations done i.e. hematological parameters, urinalysis and biochemical profile was normal. Test for LE Cell phenomenon, antinuclear antibody, rheumatoid factor, HBsAg, serological tests for syphilis and HIV were negative. CSF examination (done on 5th day) showed raised proteins while other biochemical parameters and cytology were normal. Electrophysiological studies revealed normal motor and sensory nerve conduction in upper limb nerves and in posterior tibial nerve. Increased distal latency and conduction block was noted in lateral popliteal nerve. ‘F’ wave values were prolonged marginally. MRI scan of the brain including the brain stem was normal. CSF examination done on 14th day was normal.
He was put on oral prednisolone 60 mg OD for 3 weeks and then gradually tapered off over next 2 weeks. His hypertension lasted for a week. His other symptoms remained static for next 2-3 weeks before improving gradually. He was able to stand and walk with support by the 5th week. His eyeball movements gradually returned to normal. When sent on sick leave he was off the steroids and had normal neurological functions. Follow-up in October ‘96 revealed no relapse of symptoms.
Fisher's Syndrome was first described by Miller Fisher in 1953  who considered it to be a variant of AIDP on the basis of albumino-cytological dissociation in CSF, occurrence of facial nerve palsy in some and complete recovery which are the hallmark of AIDP . Since then many cases have been reported and this variant accounts for approximately 5% of cases in a large series. There is a paucity of reports of these cases in the Indian literature with only isolated cases reported .
Controversy regarding the status arose when A1 Din et al (1982)  in a study of 18 cases of Fisher's Syndrome reported an enhancing CT Scan lesion in brain stem in three cases and suggested that these cases form a distinct clinical entity. The brunt of the pathological process is in the brain stem rather than in peripheral nerves. The authors suggested that these are examples of brain stem encephalitis. This controversy has apparently been resolved by autopsy studies in a case of Fisher's Syndrome where no brain stem or cerebellar pathology was detected . Also, electrophysiological studies indicate a peripheral lesion and a normal MRI study excludes brain stem pathology in these cases.
The patient under discussion had all the features of Fisher's Syndrome and showed transient albumino-cytological dissociation in CSF. Dysautonomia as evident by transient hypertension lasting for 7 days and electrophysiological studies confirmed peripheral nerve lesion. Also, a normal MRI scan excluded brain stem pathology. The patient made complete neurological recovery as reported in literature .