Posterior fossa reexploration for persistent or recurrent trigeminal neuralgia or hemifacial spasm: surgical findings and therapeutic implications.

OBJECTIVE: To evaluate the surgical findings and subsequent therapeutic implications of posterior fossa reexploration for persistent or recurrent trigeminal neuralgia (TN) or hemifacial spasm (HFS) after failed microvascular decompression (MVD). METHODS: Between December 1975 and October 1996, the senior author performed 31 reexplorations for failure or recurrence after MVD: 23 for TN and 8 for HFS. Records were analyzed retrospectively for evidence of vascular compression in primary and secondary operations, other pertinent intraoperative findings, intraoperative therapeutic interventions, and postoperative results and complications. RESULTS: The previously placed polyvinyl alcohol foam (Ivalon sponge; Unipoint Industries, High Point, NC) or Teflon implant (Teflon felt; CR Bard, Inc., Bard Implants Division, Billerica, MA) was found to be in good position in 100% of the patients (31 of 31 patients). New vascular compression from an arterial source was found in three patients during posterior fossa reexploration: one with TN and two with HFS. New vascular compression from a venous source was observed in one patient with HFS. A scarred Ivalon sponge or Teflon implant with apparent mass effect on the nerve root was identified in seven reexplorations. One bony source of compression was seen. No new compressive elements or other sources of root irritation were appreciated in 61% of reexplorations. Partial sensory trigeminal rhizotomy was performed in 83% of reexplorations for persistent or recurrent TN. Of eight patients undergoing reexploration for persistent or recurrent HFS, six sustained complications. CONCLUSION: Recurrent vascular compression was seldom identified during posterior fossa reexploration for failed MVD in patients with persistent or recurrent TN or HFS. The previously placed Ivalon sponge or Teflon implant was consistently found to be in good position. Partial sensory trigeminal rhizotomy is an often effective alternative in cases of recurrent TN when neurovascular compression is not identified. However, because of the relatively high incidence of complications associated with reexploration, we recommend other ablative or medical treatments for most patients after failed MVD for TN or HFS.

Science in neurosurgery: the importance of the scientific method.

The scientific method offers a way for a neurosurgeon to assess objectively his or her professional activities, especially in regard to the results of treatment. For this reason, all neurosurgical trainees should be instructed in at least the basic tenets of the scientific method, and all neurosurgeons should be guided by these tenets in their daily practice.

Midline dorsal appendages.

A case of a mature posterior cervical teratoma resembling two fingers and a case of a lumbosacral limb are presented. These are at least the seventh and eighth reported paraspinous or occipital teratomas with recognizable extremity development. Both anomalies had intradural extension and required exploration to decrease the likelihood of future spinal cord tethering. Preoperative evaluation, surgical technique, postoperative follow-up, and review of the literature are presented.

Recurrence of a cerebral arteriovenous malformation after surgical excision. Case report.

Complete excision of a cerebral arteriovenous malformation (AVM) should eliminate the future risk of an associated intracranial hemorrhage. Because total removal of an AVM may be difficult to assess at the time of surgery, postoperative angiography has become the accepted standard for documenting that the removal has been accomplished. However, even angiography confirmed excision of an AVM does not completely ensure against rebleeding. Regrowth of an AVM with subsequent hemorrhage can occur. This has been documented in children and is attributed to forces acting on the immature vasculature of these younger patients. The authors report the case of an older patient whose AVM recurred when he was 28 years of age, despite an angiography proven complete excision, and emphasize that, even in adults, angiography documentation of total removal does not always eliminate the risk of reformation of an AVM.

Neurological surgery.

Ventriculoscopy is used to open ventricular walls and barriers to the flow of cerebrospinal fluid. Surgeons have been using various donor nerves to restore some of the lost movement and sensation in brachial plexus traction or avulsion injuries.

Partial sensory trigeminal rhizotomy at the pons for trigeminal neuralgia.

Microvascular decompression is preferred among open procedures for the treatment of trigeminal neuralgia. However, in some cases the decompression cannot be performed, either because no significant vascular compression of the trigeminal nerve is found at surgery or because a patient's vascular anatomy makes it unsafe. Partial sensory rhizotomy is a commonly used alternative in these instances. The outcome after partial sensory rhizotomy was reviewed retrospectively in 83 patients with an average follow-up period of 72 months. Sixty-four (77%) of these patients had no evidence of vascular contact at operation. The remaining 19 patients (23%) had vascular structures in proximity to the trigeminal nerve but still underwent partial sensory rhizotomy in place of or in addition to microvascular decompression either because the offending vessel could not be moved adequately (11 cases) or because the vascular contact was considered insignificant (eight cases). Outcome was classified as: excellent if there was no trigeminal neuralgia postoperatively; good if pain persisted or recurred but was less severe than preoperatively; and poor if persistent or recurrent pain was equal to or greater than the preoperative pain in severity and was refractory to medication, or was severe enough to require additional surgery. The outcome was excellent in 40 patients (48%), good in 18 (22%), and poor in 25 (30%); follow-up durations were similar for the three outcome categories. The failure rate was 17% for the 1st year and averaged 2.6% each year thereafter. Two variables were predictive of a poor outcome: prior surgery and lack of preoperative involvement of the third trigeminal division. Major complications occurred in 4% of cases and minor complications in 11%. The authors conclude that partial sensory rhizotomy is a safe and effective alternative to microvascular decompression when neurovascular compression is not identified at operation or when microvascular decompression cannot be performed for technical reasons.

Hearing preservation using the modified translabyrinthine approach.

Removal of an acoustic neuroma using the translabyrinthine approach has previously been considered "incompatible" with hearing preservation. By modifying the approach and preventing the loss of endolymph, we have successfully removed two intracanalicular acoustic neuromas that originated from the inferior vestibular nerves, and preserved serviceable hearing in the ears operated on. This report represents the preliminary findings using this particular technique in the management of intracanalicular acoustic neuromas.

Spontaneous temporal encephalocele. Case report.

The authors report a 36-year-old woman with a 23-year history of simple and complex partial seizures who was treated surgically for an anteroinferior temporal encephalocele, with resolution of the seizure disorder. This patient's presentation, findings, and response to treatment are typical of those associated with anteroinferior temporal encephalocele, and different from the clinical patterns of four other types of spontaneous temporal encephalocele.

The Duke University Medical Center.

The events leading up to the creation of Duke University, the Duke University School of Medicine, and Duke Hospital are reviewed. The efforts of many individuals during more than 80 years were rewarded by an endowment and then a bequest by James B. Duke that converted Trinity College into Duke University and made possible the origination of its Medical Center. The first neurosurgical operation at the new hospital was performed on July 24, 1930, the fourth day it was open.

MRA delineation of the vertebral-basilar system in patients with hemifacial spasm and trigeminal neuralgia.

Detailed depiction of the vertebral-basilar system is often obscured by other vascular structures on the MR angiogram. A special MR angiography technique that can better delineate the branches of the vertebral-basilar system has been designed and has proved particularly useful in the identification of tortuous vascular branches when they come in contact with the seventh or fifth cranial nerves.

Hemifacial spasm: a review.

Hemifacial spasm can be diagnosed by observation and clinical history. It is thought to arise primarily from compression of the facial nerve at the pons, usually by an adjacent artery. Although many approaches to treatment have been tried, the most effective is microvascular decompression of the facial nerve at the pons. That operation has well-recognized risks, including ipsilateral deafness. The latter complication ordinarily can be avoided by the use of intraoperative monitoring of auditory evoked potentials.

Value of intraoperative brainstem auditory evoked potential monitoring in reducing the auditory morbidity associated with microvascular decompression of cranial nerves.

The present study was performed to determine whether the intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) during microvascular decompression operations is effective in preventing profound hearing loss or deafness in the ipsilateral ear. The authors retrospectively compared the auditory morbidity of posterior fossa microvascular decompression surgery for the treatment of tic douloureux and hemifacial spasm before and after the introduction of routine intraoperative BAEP monitoring in 1984. Each patient underwent a similar procedure performed by the same surgeon. The two patient groups were comparable with regard to age, sex, and indications for surgery, Auditory morbidity did not decline with the increasing experience of the surgeon prior to 1984; 10 (6.6%) of 152 primary operations (151 patients) in which monitoring was not performed were followed by a profound ipsilateral hearing loss or deafness. In the monitored group, none of 109 operations (104 patients) caused profound hearing loss or deafness. This significant decline in auditory morbidity is attributed by the authors to the use of intraoperative BAEP monitoring, which allows the surgeon to alter the operation in response to degradations in the wave patterns. Based on our experience and that of others, we believe that intraoperative BAEP monitoring is of value in reducing the auditory morbidity of posterior fossa microvascular decompression surgery.

Spinal subdural hematoma formation following ventriculoperitoneal shunting for hydrocephalus. Case report.

A case of a 14-year-old girl who developed a spinal subdural hematoma after placement of a ventriculoperitoneal shunt is presented. Such a complication has not been previously reported. We believe that this represented an extension of intracranial subdural hematoma fluid into the spinal subdural space.

Modifying the translabyrinthine approach to preserve hearing during acoustic tumour surgery.

Removing an acoustic schwannoma using the translabyrinthine approach has previously been considered incompatible with hearing preservation. By modifying the approach and preventing the loss of endolymph, we have successfully removed an intracanalicular acoustic schwannoma, which originated from the inferior vestibular nerve, and preserved hearing in the operated ear. This report represents the preliminary findings using this particular technique in the management of an intracanalicular acoustic tumour.

Surgical treatment of cluster headache.

Cluster headache is ordinarily managed medically, but may become refractory to such medical management. In this setting, surgical treatment has occasionally been performed, based on evidence that pertinent pain pathways and parasympathetic pathways may be interrupted at the main sensory root of the trigeminal nerve and at the nervus intermedius. Between 1976 and 1987, 13 patients underwent surgery for treatment of cluster headache that was refractory to medical therapy (15 procedures). Partial sectioning of the main sensory root and sectioning of the nervus intermedius were performed in nine patients; only partial sectioning of the main sensory root in one; only sectioning of the nervus intermedius in one; and nervus intermedius sectioning plus microvascular decompression of the trigeminal nerve in two. The average postoperative period for the 13 patients was 37 months (range 2 to 135 months). All patients had return of their headaches postoperatively except for one patient who obtained relief after a repeat procedure. Headache began to return between 2 days and 2 years postoperatively. Three patients are currently free of headache, including both patients who had nervus intermedius sectioning plus microvascular decompression of the trigeminal nerve. Together with recurrence of headache, cluster-associated autonomic disturbances recurred after 14 of the 15 operations but are currently absent in the three headache-free patients. Partial sectioning of the main sensory root and sectioning of the nervus intermedius, as performed in these patients, seem to have limited value in the treatment of cluster headache.

Cerebral vasospasm in conditions other than subarachnoid hemorrhage.

Intracranial arterial spasm is an arteriographically evident narrowing of the lumen of one or more of the major intracranial arteries at the base of the brain that develops in some patients 1 or more days after the rupture of an intracranial aneurysm. If it is severe enough, such cerebral vasospasm may be accompanied by cerebral ischemia or infarction. Because of its usual setting, cerebral vasospasm is thought to arise from some chemical factor or factors in the blood that accumulates within the basal subarachnoid cisterns and bathes the arteries that subsequently develop spasm. There seem to be exceptions to this basic plan, however. In patients with a ruptured aneurysm, only some of the arteries bathed in subarachnoid blood develop spasm. Of more significance, some patients develop intracranial arterial spasm without apparent subarachnoid bleeding. Until the development of CT scanning, the evidence for the lack of subarachnoid hemorrhage in such patients was weak. We now have the ability to assess cerebral vasospasm repetitively in a noninvasive manner with TCD ultrasonography and to quantitate subarachnoid hemorrhage by CT scanning. We should take advantage of this opportunity to document cases that are exceptions to the rule. Does hypothalamic damage explain such cases, or is there some other explanation? This question may be the key for unlocking the mysteries of the pathogenesis of cerebral vasospasm.

Cerebral vasospasm.

Cerebral vasospasm (specifically, intracranial arterial spasm) is variously defined as: (1) an arteriographically evident narrowing of the lumen of one or more of the major intracranial arteries at the base of the brain due to contraction of the smooth muscle within the arterial wall, or due to the morphological changes in the arterial wall and along its endothelial surface that occur in response to vessel injury; (2) the delayed onset of a neurological deficit following subarachnoid hemorrhage, thought to be due to ischemia or infarction of a portion of the brain; or (3) the combination of these two features (symptomatic vasospasm). The arterial contraction of intracranial arterial spasm typically develops a few days after the rupture of an intracranial aneurysm and lasts 2 to 3 weeks. Such arterial spasm can also occur in other conditions such as head trauma. If it is severe enough it can lead to cerebral infarction. The pathogenesis of this condition is still unclear. Many ingenious attempts have been made to prevent or treat cerebral vasospasm, but most have failed. The best current approach is to ensure adequate blood volume, and to elevate the patient's blood pressure (especially if the aneurysm has been secured by an early operation). The continuing investigation of drugs such as calcium channel blocking agents to improve the cerebral circulation has begun to provide additional help.