Petrous angle and trigeminal neuralgia.

The angle of the petrous portion of the temporal bone was measured at the site where it is crossed by the trigeminal nerve. Measurement was facilitated by using the impression techniques of dentistry to produce a plaster model of the bone, and the model was then sawn across to show the angle clearly. Considerable variation was found. Certain bone irregularities were observed and these could also conceivably be factors in the causation of trigeminal neuralgia. An attempt to reveal the angle of the petrous bone by radiology was successful in some cases but not in others. Further investigation along these lines might be of value in patients suffering from idiopathic trigeminal neuralgia.