Monday, March 23, 2009

Vagus Nerve Stimulation


The vagus nerve (left and right), or Cranial Nerve X, is the tenth cranial nerve (there are twelve in total). It begins in the brain and travels down through the chest to the organs. The functions of the vagus nerve include afferent sensory and motor information and autonomic function of viscera (digestion, heart rate).

VNS is another electrical brain stimulation technique. The difference between this method and ECT, TMS, and MST, is that the device sending the electrical impulse is surgically implanted in the chest. A wire connects this device, the pulse generator, to the left vagus nerve which is located in the back of the neck.

The device is activated by a physician after implantation (a short surgery) to deliver frequent, short impulses (30 second stimulation every 5 minutes) automatically. A magnetic device is also supplied so that the patient can turn off the stimulation by holding the magnet over the device when necessary.

It is used primarily to treat epilepsy and treatment resistant depression. Many research studies suggest promising effects of VNS on TRD especially over the long-term. As well, there is evidence that VNS improves sleep cycles, which are associated with mood. Theses studies each have their problems, as usual, causing hesitancy in the medical community.

Side effects include obstructive sleep apnea, laryngeal problems (changes in voice, coughing, pharyngitis, and bradyarrithmias.

There have been no documented cognitive side effects. The procedure is also safe to use during pregnancy.

References: 1, 2, 3, 4, 5, 6

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