Cranial Nerve III Palsy

Cranial Nerve III Palsy
SYMPTOMS Acute ptosis, diplopia, and possibly retroorbital or periorbital pain
SIGNS Typically unilateral
3-4mm ptosis (Levator palpebrae superioris paralysis), EOM restriction with involvement of the medial rectus, superior rectus, inferior oblique, and medial rectus, “Down and out” position of the eye, possible fixed and dilated pupil with loss of direct light response and accommodative response (typically seen if etiology is compression or trauma)
A complete cranial III palsy involves all associated muscles with complete paresis. A partial cranial nerve III palsy involves a few muscles with moderate paresis
WORK-UP Pupils | EOMs | Cover test | Complete eye exam with dilation | Cranial nerve testing | Ptosis testing | Forced duction testing
TREATMENT Children with a cranial nerve III palsy with or without pupil involvement should be referred to a neuro-ophthalmologist/neurologist/pediatric ophthalmologist/pediatrician/ER ASAP
Adults under 50 years old with a cranial nerve III palsy with or without pupil involvement should be referred to a neuro-ophthalmologist/neurologist/PCP/ER ASAP
Adults over the age of 50 years old with a cranial nerve III palsy without pupil involvement can be observed and referred to their PCP for a vascular work-up, but strong consideration should be given to referring patient to a neuro-ophthalmologist/neurologist/PCP/ER if cranial nerve III palsy is incomplete, if there is no improvement within 1 month, if there is progression, if there is aberrant regeneration, or if there are other neurological symptoms
Fresnel prisms can temporarily help with diplopia
Treatment depends on the underlying etiology of the CN III palsy
FOLLOW-UP Evaluate every day for the first week to make sure there is no pupil involvement. After, monitor monthly until complete resolution
ADDITIONAL LAB | TESTS Neuro-imaging is typically ordered through neuro-ophthalmologist/neurologist/PCP/pediatric ophthalmologist/pediatrician/ER and may include the following: -MRI of the brain with and without contrast | CT of the brain with and without contrast | MRA | CTA
If etiology is suspected to be due to vascular ischemia, the following should be ordered through the patient’s PCP: Blood pressure evaluation | Fasting blood sugar HbA1c | CBC with differential | ESR | C-reactive protein | ANA
ETIOLOGY Cranial nerve III damage can be secondary to the following: Vascular ischemia from systemic diseases such as diabetes | Trauma | Compression from a tumor or aneurysm | Infiltrative | Congenital due to incomplete development of the nucleus or nerve
DIFFERENTIAL DX Internuclear ophthalmoplegia, Myasthenia gravis, Thyroid eye disease, Chronic progressive external ophthalmoplegia, Orbital fracture, Brown syndrome, Ophthalmic migraine
NOTES If eye with cranial nerve III palsy is fixating, the eye that is not involved may be up and out
Cranial nerve III palsies due to vascular ischemia typically fully resolve in 3-6 months. If residual diplopia is still present, glasses with prism can be prescribed
Aberrant regeneration includes pseudo von Graefe’s sign and lid synkinesia
Different syndromes can be associated with third nerve palsies including Benedikt, Weber, Nothnagel, and Claude

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