Hemifacial Spasm
Hemifacial spasm (HFS) is a neuromuscular condition where there are sudden and involuntary bursts of tonic or clonic activity in the facial muscles innervated by the seventh cranial nerve. These contractions can occur frequently, intermittently, or continuously, and are typically limited to the side of the affected facial nerve. While the disorder is mostly unilateral, bilateral involvement can occur in severe cases. Although primary HFS is a non-serious condition and untreated cases typically do not cause any major complications, patients may face the emotional burden of societal reactions to their unusual facial movements. Thus, they may seek definitive medical or surgical treatments.
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Hemifacial spasm typically starts with brief intermittent clonic movements or twitching of the eyelid muscle (orbicularis oculi) on one side, which can result in forced closure of the eye. As the condition advances, other facial muscles (such as the corrugator, frontalis, orbicularis oris, platysma, and zygomaticus) become involved, affecting the entire middle and lower part of one side of the face. Factors such as emotional stress, fatigue, anxiety, or minor activities like reading or coughing can trigger or aggravate facial spasms. In later stages, the clonic movements progress to sustained tonic contractions of the facial muscles on the affected side. Ultimately, the spasms involve all muscles on one side of the face and become almost continuous. Although HFS is usually painless, it may be accompanied by facial pain on the same side.
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Head and neck benign tumors are frequently asymptomatic except for a palpable firm lump or mass. When symptoms occur, they are specific to the site of the tumor and result from pressure on neighboring structures caused by the slow-growing mass. Head and neck cancers can spread to nearby structures, including the respiratory, digestive, and visual tracts, interfering with essential functions such as eating, seeing, and breathing. However, early warning signs of head and neck cancers can be nonspecific and subtle. Additionally, many of these symptoms may also be caused by non-cancerous conditions.
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The medical history and neurological exam of a patient can often suggest the presence of hemifacial spasm (HFS). However, an electromyography (EMG) test is commonly performed with specialized equipment to confirm the diagnosis by stimulating and recording the activity of specific facial nerve branches. In addition, an MRI/MRA scan is usually carried out to eliminate the possibility of a mass lesion in the cerebellopontine angle and identify any blood vessel that may be irritating the facial nerve.
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Mild and early cases of hemifacial spasm can sometimes be managed with anti-seizure medications or minor tranquilizers, such as Tegretol, clonazepam, and diazepam. However, these drugs need to be taken over a long period of time, and the results are not always successful. Another option is to inject botulinum toxin directly into the affected muscles, which can stop the muscular spasms for several months, but the effect is temporary and the sensation of spasm often persists. The response to these treatments can vary, and their effects may weaken over time, which may require surgical intervention. The definitive procedure for hemifacial spasm is through microvascular decompression (MVD).