Ocularmotor Nerve Palsy (Cranial Nerve III)

Outline

Background

• Oculomotor nerve is the 3rd cranial nerve

• Oculomotor nerve supplies four ocular eye muscles: medial, superior and inferior rectus & inferior oblique

•  Oculomotor nerve has sympathetic fibres to dilate the pupil, on the outside of its fibre

Assessment

History

• Diploplia (double vision)

• Trauma

• Raised icp: headaches

Examination

• Affected eye: down and out at rest, minimal movements

• Ptosis (dropping eye lid)

• Dilated pupil (mihydrosis)

Investigations

• CT Angio: ?posterior communicating artery aneurysm ? SoL/ malignancy

• Blood pressure- Hypertension

• Blood sugar- Diabetes Mellitus 

• CRP, WCC, ESR- Vasculitis

Diagnosis

Diagnostic criteria: clinical

Classification (underlying cause):

• Surgical (extrinsic) causes- pupil dilated

• Medical (intrinsic) causes- pupil spared

Management

Acute

1. Symptomatic

   • Eye patch

   • Prism glasses

   • Advise to not drive

2. Investigate & treat underlying cause

   • Surgical removal of malignancy

   • Medical management of HTN or diabetes

Resources and References

Links

• Physiology: Nervous System

• Specialty: Neurology, Stroke

• Examination: Nervous system

References

1. https://www.ncbi.nlm.nih.gov/books/NBK526112/

Written in 2025