Neurosurgical forum Letters
to
the
editor
Geniculate Neuralgia To THE EDITOR: I read with particular interest the article by Rupa, et al. (Rupa V, Saunders RL, Weider D J: Geniculate neuralgia: the surgical management of primary otalgia. J Neurosurg 75:505-511, October, 1991). In their discussion, the authors indicate that only one patient in their study had microvascular decompression without nerve section, and this patient did not enjoy significant pain relief. I have recently treated a 43-year-old woman who had a 289 history of severe otalgia on the right side. Her problem went undiagnosed for about 189 years, when investigation and treatment of presumed temporomandibular joint disease was unsuccessful. She was placed on a course of Tegretol (carbamazepine) in August, 1990, with remarkable decrease in her pain. Unfortunately, undesirable side effects required discontinuance of the drug. She had some partial but not totally satisfactory benefit from Dilantin (phenytoin) and baclofen. The pain, located deep in the fight ear canal with some radiation along the fight mandible, was sudden in onset and lasted from a few seconds to a few minutes. The only trigger phenomenon was an increased sensitivity in the teeth in the fight mandible. Exploration was carried out through a retromastoid craniectomy in June, 1991. The trigeminal nerve root appeared normal. At the root exit/entry zone of the seventh and eighth nerves, a large circumferential loop of the anterior inferior cerebellar artery was identified. This loop provided almost complete circumferential enclosure of the seventh and eighth nerves and the nervus intermedius. Microvascular decompression was accomplished with a shredded Teflon felt prosthesis. The patient awoke with immediate pain relief, which has been maintained until the present. Initially postoperatively, she experienced marked diminution in hearing and severe vertigo, which improved over about 3 months. The patient remains pain-free. Primary otalgia is a relatively uncommon complaint. Even in an extremely active neurosurgical practice devoted in the main to the treatment of pain problems, I see perhaps one patient every year or so with this complaint. I would personally be relatively hesitant to perform an extensive supra- and infratentorial craniotomy as recommended by Rupa, et al. My own approach is to proceed by posterior fossa craniotomy to allow exploration of the trigeminal nerve and nervus intermedius as well as the ninth and 10th cranial nerves. If either microvascular decompression or section of the nervus intermedius or other nerve roots (depending on the location of the pain) proves unsuccessful, then certainly geniculate ganglionectomy could be considered on a delayed basis. 888
Although the case I have described represents only a single instance, I think it demonstrates that at least in some circumstances microvascular decompression alone, without nerve section, may relieve the pain of primary otalgia. Obviously, the follow-up period in my patient is relatively short but the immediate and lasting pain relief suggests that the etiology of the patient's pain has been identified and corrected. RONALDF. YOUNG,M.D. University of California Irvine Medical Center Orange, California RESPONSE: Dr. Young mentions three considerations that may not have been clear in our paper. The first is a trial of Tegretol (carbamazepine) for the problem of primary otalgia. Virtually all of our patients were given this drug, but only one experienced any effect (Case 8). Accordingly, the striking impact of Tegretol on Dr. Young's patient is unusual in our experience. The second consideration relates to the significance of vascular loops in and of themselves. There are some cases in which the presence of loops is inescapably important, such as that portrayed in Fig. 1 of our article. Ironically, this particular case was an utter failure, in spite of repeated surgery. My suspicion is that this failure was due to our inability to disimpact the vertebral artery from the root entry zone of the left ninth and 10th nerves. Accordingly, the observations of Dr. Young regarding the root entry zone are most consistent with our algorithm in Fig. 3. There is no conflict with his strategies and our algorithm whatsoever. On the other hand, if the neurovascular findings were not so compelling, with the appropriate rhizotomies accomplished in the posterior fossa, the dural relaxation effected by this procedure makes access to the geniculate ganglion quite simple. Finally, Dr. Young finds the strategy of performing supratentorial and infratentorial surgery at the same sitting somewhat excessive. Recognizing that 12 of our 18 patients had more than one operation, we would argue that this combined procedure was less formidable than repeated failed procedures in this territory. Our algorithm attempts to minimize the likelihood of repeated surgery by building on the ultimate recommendations of White and Sweet decades ago. Since only four of the 18 patients apparently suffered isolated neuralgias, treatment with the most complete deafferentation of the seventh, ninth, and 10th cranial nerves at one sitting remains our best advice when an obvious explanation relative to one or two cranial nerves is not found. RICHARD L. SAUNDERS,M.D. Dartmouth-Hitchcock Medical Center Lebanon, New Hampshire J.
Neurosurg. / Volume 76/May, 1992
to
the
editor
Geniculate Neuralgia To THE EDITOR: I read with particular interest the article by Rupa, et al. (Rupa V, Saunders RL, Weider D J: Geniculate neuralgia: the surgical management of primary otalgia. J Neurosurg 75:505-511, October, 1991). In their discussion, the authors indicate that only one patient in their study had microvascular decompression without nerve section, and this patient did not enjoy significant pain relief. I have recently treated a 43-year-old woman who had a 289 history of severe otalgia on the right side. Her problem went undiagnosed for about 189 years, when investigation and treatment of presumed temporomandibular joint disease was unsuccessful. She was placed on a course of Tegretol (carbamazepine) in August, 1990, with remarkable decrease in her pain. Unfortunately, undesirable side effects required discontinuance of the drug. She had some partial but not totally satisfactory benefit from Dilantin (phenytoin) and baclofen. The pain, located deep in the fight ear canal with some radiation along the fight mandible, was sudden in onset and lasted from a few seconds to a few minutes. The only trigger phenomenon was an increased sensitivity in the teeth in the fight mandible. Exploration was carried out through a retromastoid craniectomy in June, 1991. The trigeminal nerve root appeared normal. At the root exit/entry zone of the seventh and eighth nerves, a large circumferential loop of the anterior inferior cerebellar artery was identified. This loop provided almost complete circumferential enclosure of the seventh and eighth nerves and the nervus intermedius. Microvascular decompression was accomplished with a shredded Teflon felt prosthesis. The patient awoke with immediate pain relief, which has been maintained until the present. Initially postoperatively, she experienced marked diminution in hearing and severe vertigo, which improved over about 3 months. The patient remains pain-free. Primary otalgia is a relatively uncommon complaint. Even in an extremely active neurosurgical practice devoted in the main to the treatment of pain problems, I see perhaps one patient every year or so with this complaint. I would personally be relatively hesitant to perform an extensive supra- and infratentorial craniotomy as recommended by Rupa, et al. My own approach is to proceed by posterior fossa craniotomy to allow exploration of the trigeminal nerve and nervus intermedius as well as the ninth and 10th cranial nerves. If either microvascular decompression or section of the nervus intermedius or other nerve roots (depending on the location of the pain) proves unsuccessful, then certainly geniculate ganglionectomy could be considered on a delayed basis. 888
Although the case I have described represents only a single instance, I think it demonstrates that at least in some circumstances microvascular decompression alone, without nerve section, may relieve the pain of primary otalgia. Obviously, the follow-up period in my patient is relatively short but the immediate and lasting pain relief suggests that the etiology of the patient's pain has been identified and corrected. RONALDF. YOUNG,M.D. University of California Irvine Medical Center Orange, California RESPONSE: Dr. Young mentions three considerations that may not have been clear in our paper. The first is a trial of Tegretol (carbamazepine) for the problem of primary otalgia. Virtually all of our patients were given this drug, but only one experienced any effect (Case 8). Accordingly, the striking impact of Tegretol on Dr. Young's patient is unusual in our experience. The second consideration relates to the significance of vascular loops in and of themselves. There are some cases in which the presence of loops is inescapably important, such as that portrayed in Fig. 1 of our article. Ironically, this particular case was an utter failure, in spite of repeated surgery. My suspicion is that this failure was due to our inability to disimpact the vertebral artery from the root entry zone of the left ninth and 10th nerves. Accordingly, the observations of Dr. Young regarding the root entry zone are most consistent with our algorithm in Fig. 3. There is no conflict with his strategies and our algorithm whatsoever. On the other hand, if the neurovascular findings were not so compelling, with the appropriate rhizotomies accomplished in the posterior fossa, the dural relaxation effected by this procedure makes access to the geniculate ganglion quite simple. Finally, Dr. Young finds the strategy of performing supratentorial and infratentorial surgery at the same sitting somewhat excessive. Recognizing that 12 of our 18 patients had more than one operation, we would argue that this combined procedure was less formidable than repeated failed procedures in this territory. Our algorithm attempts to minimize the likelihood of repeated surgery by building on the ultimate recommendations of White and Sweet decades ago. Since only four of the 18 patients apparently suffered isolated neuralgias, treatment with the most complete deafferentation of the seventh, ninth, and 10th cranial nerves at one sitting remains our best advice when an obvious explanation relative to one or two cranial nerves is not found. RICHARD L. SAUNDERS,M.D. Dartmouth-Hitchcock Medical Center Lebanon, New Hampshire J.
Neurosurg. / Volume 76/May, 1992
