Cranial Nerve Palsies

There are a number of conditions and diseases associated with cranial nerve palsies. These are:

• Diabetes mellitus
• Tuberculosis
• Carcinoma
• Rheumatoid arthritis
• Systemic lupus erythaematosus (SLE) and other connective tissue disorders
• Sarcoidosis
• Leprosy
• Lyme disease
• HIV
• Amyloidosis

ALL of these can involve one or more cranial nerves.

Guillain-Barre syndrome (GBS) and hereditary motor and sensory neuropathies (HMSN) are also associated with cranial nerve involvement.

Cranial nerve palsies are well described in Listeria meningitis.

Cranial nerve palsy mimics

Certain other conditions masquerade as cranial nerve palsies. In particular:

• Myasthenia gravis causes weakness of the ocular muscles, and therefore mimics an ocular palsy
• Rabies can mimic GBS, including facial weakness
• Thyroid eye disease also causes non-neurological ocular palsies

Unless there is an obvious cause, investigation for cranial nerve injury starts with imaging, either computerised tomography (CT) head or preferably magnetic resonance imaging (MRI), if available.

Imaging is mandatory for cranial nerve palsies associated with trauma.