Optic nerve (ON) takes most of its origin from the C2 nerve root. It has two branches: the greater and lesser. Greater ON is more prone to injury. Damage to the C2 nerve root, and possibly also the upper cord, can cause occipital neuralgia. Trauma to ON is often caused by a direct impact on the eyeball/socket, such as seen in automobile crashes. It may occur due to spondylosis of the upper cervical spine (C1-C2), or focal neuropathies secondary to diabetes or tumor. It may occur when the occipital nerve is entrapped anywhere along its course. Other causes of damage to ON include physical stress on the nerve, repetitive neck contraction, flexion or extension, or tumor.
Occipital neuralgia is characterized by paroxysms of severe occipital pain and severe tenderness just below their occiput, which may resemble severe migraines. The episodes may be associated with extreme spikes in blood pressure. There can be referred pain in the eye or teeth. Dizziness may be an associated symptom of occipital neuralgia and is likely a variant of cervical vertigo. Other symptoms include blurred vision, sensitivity to light and sound, slurred speech, difficulty with balance and coordination, nausea and/or vomiting.
- cervical facet pain
- myofascial pain syndrome
- optic neuritis
It is a clinical diagnosis based on symptoms. For injury-associated cases, MRI or CT scan of the skull base is the most common test. A CT scan of the cervical spine is probably the most useful because it visualizes the cervical facet joints. MRI of the neck to evaluate the soft tissue of the neck. Rarely, vascular imaging may be done to look for carotid or vertebral dissection or vascular compression.
Medications are usually not helpful for occipital neuralgia. Nerve blocks are the best choice for adequate pain control. They are indicated when the nerve is bruised. If the site of injury is one of the upper cervical nerve roots, then a more complex C2 cervical nerve block may need to be used. X-ray guidance is often required. If the damage is caused to the cervical facet nerve or to the occipital nerves close to the spinal cord prior to emerging into the skull, it would be untouched by a peripheral occipital nerve block. Greater ON nerve block improves Dizziness in more than half the patients with trauma.
For a more lasting effect, a more permanent procedure is to damage the nerve through Radiofrequency ganglion-neurectomy, cryotherapy, Botox or phenol.
Decompression surgery of the occipital nerve may be necessary to perform in select cases. Rhizotomy surgery means cutting of nerves and may be used to convert a neuralgia into a numbness, but it may cause denervation pain. Andrychowski et al (2009) discuss surgical approaches. To us, this seems to be similar to RFGN, but less sophisticated.
Other treatment options include Occipital nerve stimulator, anticonvulsants, and antidepressants.