palsy

A 52-year-old female with a past medical history of hypertension and prediabetes presented to the emergency department with double vision that started one day prior to arrival. She stated that her double vision improved when she closed one eye. She denied trauma, headache, neck pain, dizziness, dysphagia, numbness, tingling, weakness, or gait instability.

Vitals: BP 181/119; HR 76; RR 18; T 98.4°F; O2 saturation 96% on room air

General: No acute distress, well-appearing

Neurologic: AOx3; Following commands. Speech without dysarthria. PERRLA. EOM: incomplete abduction of the L and R eye. No facial asymmetry. Tongue protrudes midline. No pronator drift. 5/5 strength in all extremities. Sensation is intact throughout. Finger to nose is normal. Gait is narrow and steady.

Cranial nerve 6 (CN VI), also known as the abducens nerve, is responsible for ipsilateral eye movement. CN VI palsy presents clinically with the inability to abduct the eye resulting in horizontal diplopia. Patients often present complaining of double vision that is worse with lateral gaze. Other symptoms on presentation may include headache, nausea, vomiting, hearing loss, and recent viral symptoms. CN VI is typically diagnosed clinically by an inability to abduct the eye. It is the most common oculomotor palsy in adults and can be caused by damage anywhere along the course of the abducens nerve. Etiologies in adults include ischemia, trauma, neoplasm, demyelinating lesions, increased intracranial pressure, and infection. Risk factors include microvascular disease such as hypertension and inflammatory conditions. Bilateral CN VI nerve palsy without associated intracranial abnormalities is rare. Importantly, abducens nerve palsy is the second most common oculomotor palsy in children and a frequent presenting sign of an intracranial tumor. Children with CN VI palsy should be evaluated for ataxia and other gait disturbances which may indicate a brainstem glioma.

Depending on the presenting symptoms and medical history, the workup should include an MRI/MRA brain to evaluate for microvascular ischemia and cerebrovascular accident. Treatment of CN VI palsy should be targeted at the underlying cause. In cases of CN VI palsy due to microvascular ischemia, symptoms often self-resolve. In children, treatment includes alternating patching of the eyes, but this has not been shown to be effective in adults.

Take-Home Points

  • CN VI palsy is the most common oculomotor palsy in adults and presents with an inability to abduct the eye.
  • Treatment of CN VI palsy should target the underlying pathology which may include infection, trauma, neoplasm, or increased intracranial pressure.
  • CN VI palsy in children may indicate an intracranial tumor and workup should include a full neurologic examination and intracranial imaging when appropriate.
  • Graham C, Gurnani B, Mohseni M. Abducens Nerve Palsy. 2023 Aug 24. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan–. PMID: 29489275.

    Merino P, Gómez de Liaño P, Villalobo JM, Franco G, Gómez de Liaño R. Etiology and treatment of pediatric sixth nerve palsy. J AAPOS. 2010 Dec;14(6):502-5. doi: 10.1016/j.jaapos.2010.09.009. PMID: 21168073.

Tanesha Beckford, MD

Tanesha Beckford, MD

Resident Physician
Boston Medical Center
Tanesha Beckford, MD

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Brigid Garrity, DO, MPH

Brigid Garrity, DO, MPH

Resident Physician
Boston Medical Center
Brigid Garrity, DO, MPH

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Andrew Mittelman, MD

Andrew Mittelman, MD

Assistant Professor of Emergency Medicine
Boston Medical Center