Hemifacial Spasm and Desflurane (HFS)
Patients are chosen to participate in this study because they will undergo a particular type of brain surgery to treat their hemifacial spasm. This surgery is called microvascular decompression (MVD) and involves the facial nerve. The facial nerve is being compressed by one or more blood vessels and this contact produces the facial twitches. The investigators do not know why a blood vessel that touches the facial nerve produces facial twitches. The investigators are interested in investigating this during your surgery. A total of 25 participants are expected to participate in this study.
|Study Design:||Observational Model: Case Control
Time Perspective: Prospective
|Official Title:||Investigating the Etiology of Hemifacial Spasm (HFS): The Role of Desflurane|
- Measure EMG responses to peripheral nerve stimulation and motor cortex stimulation during changes in desflurane levels [ Time Frame: one year ] [ Designated as safety issue: No ]
|Study Start Date:||November 2012|
|Estimated Study Completion Date:||December 2013|
|Estimated Primary Completion Date:||December 2013 (Final data collection date for primary outcome measure)|
hemifacial spasm, lateral spread, motor evoked potentials
EMG recordings from facial muscles of HFS patients during MVD surgery will be compared during total intravenous anesthesia (propofol), 0.5 MAC desflurane and 1.0 MAC desflurane
"Intra Operative Monitoring" (IOM) is a standard and routine medical practice for patients having MVD surgery. IOM is done to make sure that the hearing and face nerves are not accidentally bumped or damaged during surgery. After anesthetic induction, the neurophysiologist places electrodes for the nerves, on the scalp and muscles. Stimulation and monitoring of muscle twitches are all common, safe and painless medical procedures.
In this study, the investigators would like to measure the nerve and muscle function on the normal side and compare it to nerve and muscle function on the abnormal side during different levels of the anesthetic desflurane. In order to monitor the normal side of the face one additional set of electrodes will be placed in the facial muscles. The investigators will compare responses to three different levels of anesthetic. The technique used will be motor evoked potentials. The effect of the anesthesia on the lateral spread response will also be examined. This response is evident only on the symptomatic side. These observations will take approximately 10 to 15 minutes and will not delay or lengthen the surgery.