Trigeminal neuralgia: a quantitative sensory perception threshold study in patients who had not undergone previous invasive procedures.

The authors investigated 28 patients with "idiopathic" trigeminal neuralgia who had undergone no previous invasive procedures; together these patients had a total of 50 affected trigeminal divisions. Quantitative sensory perception thresholds were measured before operation. Preoperative measurements in the affected divisions indicated raised thresholds for touch (von Frey filaments) and temperature, but not for pinprick or heat pain, in agreement with the findings of Nurmikko. Only the tactile threshold was also significantly affected in the unaffected divisions on the affected side. The authors discuss their findings in relation to the pathophysiology of trigeminal neuralgia, concluding that the origin of the condition is almost certainly central to the gasserian ganglion.

Sensory effects of microvascular decompression in trigeminal neuralgia.

Nineteen patients with "idiopathic" trigeminal neuralgia, who had not undergone any previous interventional procedures, possessed a vessel or vessels compressing the preganglionic nerve root that was demonstrated by magnetic resonance tomographic angiography. Pain was relieved immediately in all of these patients after they underwent microvascular decompression without observed nerve damage. Although preoperative measurement of sensory perception thresholds showed elevations in the thresholds for touch (von Frey filaments) and warmth and coolness sensations, these thresholds normalized during the postoperative period. An apparent deficit in the pinprick (sharpness) sensation appeared postoperatively, but the deficit gradually regressed and completely disappeared by 1 year after surgery; this phenomenon may have been a statistical anomaly. The patients' pain disappeared immediately postoperatively and remained absent throughout the follow-up period. The authors conclude that damage to the nerve or nerve root is not essential for the relief of trigeminal neuralgia.