Percutaneous Retrogasserian Glycerol Rhizotomy for Trigeminal
Percutaneous Retrogasserian Glycerol Rhizotomy for Trigeminal
Object: In the management of trigeminal neuralgia (TN), physicians seek rapid and long-lasting pain relief, together with preservation of trigeminal nerve function. Percutaneous retrogasserian glycerol rhizotomy (PRGR) offers distinct advantages over other available procedures. The aim of this report was to provide details of the PRGR procedure and its expected outcome.
Methods: The authors reviewed their experience with PRGR in 1174 patients to evaluate the procedural technique, results, and complications. Although it is clear that TN is not a static disorder but one characterized by remissions and recurrences, long-lasting pain relief was noted in 77% of patients, with 55% discontinuing all medications and 22% requiring some drug usage.
Conclusions: The authors discuss the role of PRGR in their practice, along with other procedures such as microvascular decompression and gamma knife surgery, for idiopathic or multiple sclerosisrelated TN. They conclude that PRGR had distinct advantages over other procedures, which include eliminating the need for intraoperative confirmatory sensory testing, and a lower risk of facial sensory loss.
The clinical challenge of TN has many medical and surgical resolutions. In patients whose disease is medically refractory because of sustained, intolerable side effects from medication, a surgical procedure is considered. The choices include procedures that aim to manage the cause of the pain, such as MVD, or those that treat the nerve but "ignore" the cause of the pain (different rhizotomy procedures). Stereotactic radiosurgery, when performed at the anatomical location of vascular compression, may also work to "treat the cause," but it is believed that the effect of this modality is based more on selective axonal degeneration of the nerve. Whenever any clinical problem is treated with a wide variety of surgical alternatives, it is because one procedure does not provide a uniform benefit for all patients. This was the case with TN, for which different surgical procedures were developed, and the different rhizotomy procedures aim to treat the nerve in different ways. These include mechanical effects on the nerve (balloon microcompression, thermal-induced axonal degeneration by radiofrequency rhizotomy, radiation-induced degeneration produced by stereotactic radiosurgery, or chemical ablation with glycerol rhizotomy). Injection of chemical agents into peripheral nerve targets (that is, alcohol injections) are also available.
Interestingly, in earlier centuries, other possible surgical remedies included carotid ligation, galvanic stimulation, dental procedures (some still performed today), and abdominal surgery such as appendectomy and colon resection. Direct alcohol injection into the trigeminal nerve was reported in 1910. According to Burchiel, Härtel gets credit for the accepted technique of spinal needle placement into the trigeminal cistern. When absolute alcohol was injected into this location, multiple severe cranial neuropathies could be seen. Jefferson advocated the use of phenol mixed with glycerin rather than absolute alcohol.
Lars Leksell had long been interested in the use of focused radiation for the management of TN. In his initial work in the early 1950s, he coupled an orthovoltage x-ray tube to a stereotactic frame to irradiate the trigeminal ganglion. The first-generation gamma knife was built in 1967. Leksell conceived its use for focal irradiation of functional brain targets. Before performing the procedure, he needed a way to identify the nerve consistently by using standard xray films in the era before computerized tomography scans. To localize the nerve for radiosurgery, Leksell and Häkanson injected tantalum dust mixed with glycerol into the trigeminal cistern as a marker. When this targeting solution was injected prior to radiosurgery, patients noted pain relief, and PRGR was born as a new surgical procedure.
In our management of TN, our goals are rapid and longlasting pain relief, together with preservation of trigeminal nerve function. The PRGR technique offers distinct advantages over other percutaneous procedures. These include eliminating the need for intraoperative confirmatory sensory testing (patient cooperation is not necessary) or a radiofrequency generator. The patient simply need not "participate" during the procedure and thus can be more deeply anesthetized. Precise anatomical localization of the target is performed using intraoperative cisternography rather than asking the patient to describe radiofrequency-induced sensory changes. Glycerol is associated with a lower risk of facial sensory loss compared with either radiofrequency rhizotomy or balloon microcompression. This feature significantly reduces the risk of deafferentation pain. We believe that pain relief without significant sensory loss and without high surgical risk is possible for virtually all patients by using MVD, PRGR, or stereotactic radiosurgery, either alone or in combination. The choice of procedure is related to the factors of patient age, medical condition, symptom severity, and personal preference. Glycerol rhizotomy remains our preferred primary surgical procedure for patients with multiple sclerosisrelated TN.
Object: In the management of trigeminal neuralgia (TN), physicians seek rapid and long-lasting pain relief, together with preservation of trigeminal nerve function. Percutaneous retrogasserian glycerol rhizotomy (PRGR) offers distinct advantages over other available procedures. The aim of this report was to provide details of the PRGR procedure and its expected outcome.
Methods: The authors reviewed their experience with PRGR in 1174 patients to evaluate the procedural technique, results, and complications. Although it is clear that TN is not a static disorder but one characterized by remissions and recurrences, long-lasting pain relief was noted in 77% of patients, with 55% discontinuing all medications and 22% requiring some drug usage.
Conclusions: The authors discuss the role of PRGR in their practice, along with other procedures such as microvascular decompression and gamma knife surgery, for idiopathic or multiple sclerosisrelated TN. They conclude that PRGR had distinct advantages over other procedures, which include eliminating the need for intraoperative confirmatory sensory testing, and a lower risk of facial sensory loss.
The clinical challenge of TN has many medical and surgical resolutions. In patients whose disease is medically refractory because of sustained, intolerable side effects from medication, a surgical procedure is considered. The choices include procedures that aim to manage the cause of the pain, such as MVD, or those that treat the nerve but "ignore" the cause of the pain (different rhizotomy procedures). Stereotactic radiosurgery, when performed at the anatomical location of vascular compression, may also work to "treat the cause," but it is believed that the effect of this modality is based more on selective axonal degeneration of the nerve. Whenever any clinical problem is treated with a wide variety of surgical alternatives, it is because one procedure does not provide a uniform benefit for all patients. This was the case with TN, for which different surgical procedures were developed, and the different rhizotomy procedures aim to treat the nerve in different ways. These include mechanical effects on the nerve (balloon microcompression, thermal-induced axonal degeneration by radiofrequency rhizotomy, radiation-induced degeneration produced by stereotactic radiosurgery, or chemical ablation with glycerol rhizotomy). Injection of chemical agents into peripheral nerve targets (that is, alcohol injections) are also available.
Interestingly, in earlier centuries, other possible surgical remedies included carotid ligation, galvanic stimulation, dental procedures (some still performed today), and abdominal surgery such as appendectomy and colon resection. Direct alcohol injection into the trigeminal nerve was reported in 1910. According to Burchiel, Härtel gets credit for the accepted technique of spinal needle placement into the trigeminal cistern. When absolute alcohol was injected into this location, multiple severe cranial neuropathies could be seen. Jefferson advocated the use of phenol mixed with glycerin rather than absolute alcohol.
Lars Leksell had long been interested in the use of focused radiation for the management of TN. In his initial work in the early 1950s, he coupled an orthovoltage x-ray tube to a stereotactic frame to irradiate the trigeminal ganglion. The first-generation gamma knife was built in 1967. Leksell conceived its use for focal irradiation of functional brain targets. Before performing the procedure, he needed a way to identify the nerve consistently by using standard xray films in the era before computerized tomography scans. To localize the nerve for radiosurgery, Leksell and Häkanson injected tantalum dust mixed with glycerol into the trigeminal cistern as a marker. When this targeting solution was injected prior to radiosurgery, patients noted pain relief, and PRGR was born as a new surgical procedure.
In our management of TN, our goals are rapid and longlasting pain relief, together with preservation of trigeminal nerve function. The PRGR technique offers distinct advantages over other percutaneous procedures. These include eliminating the need for intraoperative confirmatory sensory testing (patient cooperation is not necessary) or a radiofrequency generator. The patient simply need not "participate" during the procedure and thus can be more deeply anesthetized. Precise anatomical localization of the target is performed using intraoperative cisternography rather than asking the patient to describe radiofrequency-induced sensory changes. Glycerol is associated with a lower risk of facial sensory loss compared with either radiofrequency rhizotomy or balloon microcompression. This feature significantly reduces the risk of deafferentation pain. We believe that pain relief without significant sensory loss and without high surgical risk is possible for virtually all patients by using MVD, PRGR, or stereotactic radiosurgery, either alone or in combination. The choice of procedure is related to the factors of patient age, medical condition, symptom severity, and personal preference. Glycerol rhizotomy remains our preferred primary surgical procedure for patients with multiple sclerosisrelated TN.
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