What is the management approach for a patient presenting with Miller Fisher syndrome, characterized by acute ataxia, presence of lymphocytes in the cerebrospinal fluid (CSF), and nystagmus?

Management of Miller Fisher Syndrome

Intravenous immunoglobulin (IVIG) at 0.4 g/kg/day for 5 days (total dose 2 g/kg) is the first-line treatment for Miller Fisher syndrome, with plasmapheresis as an equally effective alternative. 1, 2

Diagnostic Confirmation

Before initiating treatment, confirm the diagnosis through:

• Anti-GQ1b antibody testing in serum, which is highly specific for Miller Fisher syndrome and supports the diagnosis even when CSF findings are atypical 2, 3
• Cerebrospinal fluid analysis looking for albuminocytologic dissociation (elevated protein with normal cell count), though this may be absent early in the disease course or in atypical presentations 3, 4
• Clinical triad assessment: ophthalmoplegia, ataxia, and areflexia—though incomplete forms exist with isolated findings 1, 2

Critical pitfall: Do not delay treatment waiting for CSF confirmation or anti-GQ1b results if clinical suspicion is high, as symptoms can progress rapidly to respiratory failure 5, 6

Immediate Treatment Protocol

First-Line Immunotherapy

IVIG is preferred due to ease of administration and equivalent efficacy to plasmapheresis 1, 2:

• Dosing: 0.4 g/kg/day intravenously for 5 consecutive days 1, 2
• Start within 24 hours of admission when diagnosis is suspected, even before confirmatory testing returns 3

Plasmapheresis is an alternative when IVIG is contraindicated or unavailable 1, 2:

• Performed over 5 days with similar efficacy to IVIG 1, 2

Corticosteroids alone are not recommended as monotherapy, though they may be considered in combination with IVIG in severe cases with respiratory compromise 1

Respiratory Monitoring and Support

This is the most critical aspect of management, as 15-30% of patients require ventilatory support 2:

• Measure negative inspiratory force (NIF) and vital capacity every 4-6 hours in the acute phase 5, 3
• Intubate prophylactically if NIF worsens to -20 to -30 cmH2O (normal < -60) or vital capacity falls below 15 mL/kg 5, 3
• Monitor for bulbar involvement (dysphagia, dysarthria) which increases aspiration risk 5, 6

Common pitfall: Patients can deteriorate rapidly from stable respiratory function to requiring intubation within hours, particularly on days 2-3 of hospitalization 5, 3, 6

Daily Clinical Monitoring

Perform daily neurological assessments tracking 2:

• Cranial nerve function, particularly extraocular movements
• Deep tendon reflexes in all extremities
• Coordination testing (finger-to-nose, heel-to-shin)
• Ascending weakness patterns
• Bulbar function (swallowing, speech)

Supportive Care Measures

• Prevent aspiration: NPO status or modified diet if bulbar weakness present 6
• DVT prophylaxis: Sequential compression devices and/or pharmacologic prophylaxis given immobility 5
• Bladder management: Monitor for urinary retention, which can occur in atypical presentations 3
• Physical therapy: Begin early mobilization as tolerated to prevent deconditioning 3

Expected Clinical Course and Disposition

Prognosis is generally favorable with case fatality rate <5% and most patients recovering within weeks to months 2:

• Symptoms typically improve within 1-2 weeks of starting IVIG 3, 4
• Complete recovery may take 6 weeks or longer 3
• Patients requiring intubation may need tracheostomy and PEG tube placement for prolonged support 5
• Discharge to acute rehabilitation or long-term acute care facility is common for severe cases 5

Important consideration: Approximately 15% of Miller Fisher syndrome cases overlap with classical Guillain-Barré syndrome, presenting with more extensive limb weakness beyond the typical triad 1, 2

Atypical Presentations to Recognize

Be aware that Miller Fisher syndrome can present without the complete triad 3, 7:

• Isolated ataxia without ophthalmoplegia initially 7
• Unilateral ophthalmoplegia progressing to bilateral 4
• Absent areflexia at presentation, developing later 3
• Normal CSF protein early in disease course 3
• Prominent sensory symptoms or ascending paresthesias 3, 7

These atypical presentations should not delay treatment if clinical suspicion is high based on acute onset, preceding infection, and evolving neurological deficits 3, 7