Radiation to the head and neck can result in a cranial neuropathy.
Patient selection: cancer of the head and neck
The onset is often delayed, sometimes 10 years or more.
Risk factors:
(1) radiation field includes midbrain and brainstem
(2) radiation field includes path of the cranial nerve
(3) high radiation dose
(4) repeated courses of radiation therapy
(5) neck fibrosis
(6) concurrent chemotherapy
Some of the tumors associated with cranial neuropathy are nasopharyngeal and oropharyngeal cancer.
Nerves affected may include one or more of the following:
(1) spinal accessory (CN 11)
(2) glossopharyngeal (CN 9)
(3) vagus (CN 10)
(4) hypoglossal (CN 12)
(5) third cranial nerve
(6) vestibulocochlear (CN 8)
Symptoms may include:
(1) dysphagia
(2) ophthalmoplegia
(3) decreased hearing
(4) laryngeal palsy with easy choking and hoarseness
(5) alterations in taste
(6) weak facial muscles
(7) difficulty with speech
These may resemble a bulbar palsy.
On electromyography affected nerves may show myokymic discharges
