What Is Vascular Compression?
Vascular compression refers to a group of cranial nerve syndromes. When cranial nerves exit the brain, they travel a short distance through brain fluid before they exit the skull. Also traveling in the brain fluid are blood vessels that supply the brain and nerves. If the two become tangle, the blood vessels may compress the nerves resulting in dysfunction.
What Are the Symptoms of Vascular Compression?
The symptoms depend on the particular nerve being compressed. The two most commonly compressed nerves are the trigeminal nerve and the facial nerve.
The trigeminal nerve is the fifth cranial nerve and provides sensation to the face. Compression of the trigeminal nerve results in trigeminal neuralgia, or nerve pain of the forehead, cheek, jaw, or eye. It is often described as stabbing or shocking pain. It may be triggered by light touch or a gust of wind on the face. Talking, chewing, shaving, etc have also been described as triggers.
The facial nerve is the seventh cranial nerve and provides movements of facial expression. Compression of the facial nerve causes involuntary facial movements called hemifacial spasm. This involves uncontrolled movements of half of the face. These spasms can interfere with patients’ abilities do drive, read, work, and socialize. The impact on quality of life is substantial. Initially the spasms involve the eye but as the disease progresses, it spreads to the lower portion of the face.
Other cranial nerve involvement is less common. Involvement of the audiovestibular nerve, or 8th cranial nerve, is controversial. Symptoms may include tinnitus, hearing loss, episodic vertigo, positional vertigo, disequilibrium, and imbalance. The glossopharyngeal nerve or 9th cranial may be compressed resulting in ear, throat, or tongue pain. Involvement of these other cranial nerve is difficult to separate out from other causes because of the vague nature of symptoms.
How Will My Doctor Test for Vascular Compression Syndromes?
If a vascular compression syndrome is suspected, testing may include a audiogram (hearing test), VNG (balance test), ECOG (test for Meniere’s disease), and ABR (brainstem hearing test). An MRI is always ordered. These tests are to look for other causes as much as they are to diagnose vascular compression. If no other causes are found and suspicion for vascular compression is high then treatment may be discussed for vascular compression.
How Are Vascular Compressive Syndromes Treated?
Trigeminal neuralgia is treated with daily medications. These may include medications for nerve pain (gabapentin), antiseizure medications (tegretol, valproic acid, phenytoin), or relaxing medications (clonazepam, baclofen). Sometimes the side effects of these are not tolerated by patients. Other times these medications do not provide relief.
Hemifacial spasm does not respond as well to daily medications. Botox injections are effective. They need to be repeated every few months to keep the spasms controlled.
What if Medications Do Not Work for Vascular Compression?
If medications fail to relieve symptoms are cause intolerable side effects, surgery can be done to decompress the affected nerve. This is called a microvascular decompression. It involves a craniotomy to open a window in the skull. The offending nerve is located by delicate retraction of the cerebellum and release of brain fluid. The lining of the nerve is opened to release tension. The vessel is carefully dissected off the nerve. A biocompatible cushion may be placed between the nerve and vessel to decrease recurrence if needed. After surgery is completed a 1-2 day stay in the hospital is expected. Complications are rare but include headache, brain fluid leak, hearing loss, facial droop, facial numbness, stroke, and recurrence of vascular compression. Of these, recurrence is the most common, but is still unlikely.
In cases of trigeminal neuralgia when medications fail and surgery is not an option due to age or poor health, radiation of the trigeminal nerve is used. This has also been reported in a few cases of hemifacial spasm, but is not routine.