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OBJECTIVEHemifacial spasm (HFS), largely caused by neurovascular compression (NVC) of the facial nerve, is a rare condition characterized by paroxysmal, unilateral, involuntary contraction of facial muscles. It has long been suggested... more
OBJECTIVEHemifacial spasm (HFS), largely caused by neurovascular compression (NVC) of the facial nerve, is a rare condition characterized by paroxysmal, unilateral, involuntary contraction of facial muscles. It has long been suggested that these symptoms are due to compression at the transition zone of the facial nerve. The aim of this study was to examine symptom-free survival and long-term quality of life (QOL) in HFS patients who underwent microvascular decompression (MVD). A secondary aim was to examine the benefit of utilizing fused MRI and MRA post hoc 3D reconstructions to better characterize compression location at the facial nerve root exit zone (fREZ).METHODSThe authors retrospectively analyzed patients with HFS who underwent MVD at a single institution, combined with a modified HFS-7 telephone questionnaire. Kaplan-Meier analysis was used to determine event-free survival, and the Wilcoxon signed-rank test was used to compare pre- and postoperative HFS-7 scores.RESULTSThir...
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Modest cold exposures are likely to activate autonomic thermogenic mechanisms due to activation of cutaneous thermal afferents, whereas central thermosensitive neurons set the background tone on which this afferent input is effective. In... more
Modest cold exposures are likely to activate autonomic thermogenic mechanisms due to activation of cutaneous thermal afferents, whereas central thermosensitive neurons set the background tone on which this afferent input is effective. In addition, more prolonged or severe cold exposures that overwhelm cold defense mechanisms would directly activate thermosensitive neurons within the central nervous system. Here, we examined the involvement of the canonical brown adipose tissue (BAT) sympathoexcitatory efferent pathway in the response to direct local cooling of the preoptic area (POA) in urethane-chloralose anesthetized rats. With skin temperature and core body temperature maintained between 36 {degree sign}C and 39 {degree sign}C, cooling POA temperature by approximately 1-4{degree sign}C evoked increases in BAT sympathetic nerve activity (SNA), BAT temperature, expired CO, and heart rate. POA cooling-evoked responses were inhibited by nanoinjections of ionotropic glutamate receptor...
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Typical trigeminal neuralgia is characterized by episodic, unilateral, lancinating, triggerable, often shock-like facial pains, and pain-free intervals. Trigeminal neuropathic pain could be defined as constant unilateral facial pain of... more
Typical trigeminal neuralgia is characterized by episodic, unilateral, lancinating, triggerable, often shock-like facial pains, and pain-free intervals. Trigeminal neuropathic pain could be defined as constant unilateral facial pain of variable intensity, is non-triggerable, and unremitting. Atypical trigeminal neuralgia is an overlap syndrome with both episodic and constant pain. Patients with clear pathology of the trigeminal system often have sensory loss and atypical pains. The leading theory of causation of typical trigeminal neuralgia points to minimal compression and demyelination at the root entry zone (REZ) of the trigeminal nerve. In the experience of many neurosurgeons, atypical pains result from lesions or injuries of the trigeminal nerve root distal to the REZ. In a review of 122 patients, distal trigeminal pathology correlated with a clinical syndrome of trigeminal neuropathic pain. An hypothesis is presented that peripheral lesions of the trigeminal nerve behave as do other peripheral nerve lesions in that they are associated with sensory loss, deafferentiation and non "tic-like" pains. This may be due to the asynchronous spatial temporal dispersion of abnormal centrally-propagating axonal activity in nociceptive and non-nociceptive fibers from the region of pathology. This is opposed to the putative synchronous multifiber volleys which may emanate from the proximal trigeminal REZ in patients with typical trigeminal neuralgia. It appears that classical trigeminal neuralgia may be an exception to the rule that nerve injuries typically produce symptoms like constant pain and allodynia. Trigeminal neuropathic pain is, in some ways, a more general syndrome in that it is a painful nerve injury of the distal trigeminal nerve.(ABSTRACT TRUNCATED AT 250 WORDS)
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Chronic application of alumina cream to the trigeminal ganglion in 10 cats failed to produce a long-lasting behavioral syndrome of facial dysesthesia. Histologic and electron microscopic analysis demonstrated morphologic similarities... more
Chronic application of alumina cream to the trigeminal ganglion in 10 cats failed to produce a long-lasting behavioral syndrome of facial dysesthesia. Histologic and electron microscopic analysis demonstrated morphologic similarities between these ganglia and primate neocortical alumina cream epileptic foci. None of 87 ganglia neurons recorded extracellularly exhibited evidence of intrinsic hyperexcitability, i.e., abnormal spontaneous or physiologically evoked activity or any significant differences in threshold of responses to antidromic or orthodromic electrical stimulation, compared to 67 normal ganglion cells. Furthermore, topical application of penicillin to normal ganglia failed to produce abnormal activity in 42 neurons tested. These data suggest that neuronal somata lacking either dendrites or postsynaptic membranes, or both, do not develop abnormal firing behavior when challenged with these two epileptogenic agents.
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A technique for extended ambulatory epidural pain control after lumbar discectomy is described; preliminary results with 45 patients are reported; and alternative methods of narcotic analgesia are reviewed. In this technique, an... more
A technique for extended ambulatory epidural pain control after lumbar discectomy is described; preliminary results with 45 patients are reported; and alternative methods of narcotic analgesia are reviewed. In this technique, an absorbable gelatin sponge (Gelfoam, Upjohn Co., Kalamazoo, MI) is contoured to the laminotomy defect, placed in methylprednisolone acetate (40-80 mg), and then injected with 2 to 4 mg of preservative-free morphine (a small needle was used to fill the sponge). The sponge is placed over the defect before closure. A review of office and hospital records was conducted. The series consisted of 33 men and 12 women (mean age, 39 yr; range, 24-57 yr); records showed narcotic use in 34 patients (parenteral in 3) and work-related injuries in 14 patients. Thirty-three patients were ambulatory postoperatively on the day of surgery; all were ambulatory by postoperative day (POD) 1. On the day of surgery, 18 patients did not require any postoperative analgesics; on POD 1, 22 patients did not require analgesics. Six patients received parenteral narcotics; four received one dose only, and two had two or more doses. Thirty-one patients were discharged from the hospital on POD 1, and 10 were discharged POD 2. The other patients were discharged from the hospital on POD 3 (three patients) or POD 4 (one patient). When they were discharged, all patients received a limited supply of acetaminophen with codeine for pain control at home. After discharge, phone follow-up (at 1 week) and office follow-ups (at 3-5 weeks) revealed only one patient with more than mild discomfort. Three patients required one-time bladder catheterization, and one patient had presumed discitis 1 month postoperatively. In a control group who had undergone surgery 3 months previously, the average day of discharge had been POD 3.07; no control patient had been discharged on POD 1, and only 20% had been discharged on POD 2. This method provides effective, safe, and extended analgesia after lumbar discectomy.
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An applicator system for the Leksell G frame was constructed to enable accurate placement of the frame for stereotactic magnetic resonance imaging (MRI) and successful stereotactic surgery. The applicator prevents inaccurate placement of... more
An applicator system for the Leksell G frame was constructed to enable accurate placement of the frame for stereotactic magnetic resonance imaging (MRI) and successful stereotactic surgery. The applicator prevents inaccurate placement of the fiducial box on the patient's head and prevents contact of the frame holder with the patient's shoulder while in the MRI unit. It also helps to ensure optimal positioning of desired targets within the three-dimensional stereotactic space defined by the frame. The applicator is made of transparent acrylic plates, which simulate the fiducial box that is attached to the frame for the preoperative stereotactic MRI study. An air cuff at the top supports the frame at any desired height and makes minute adjustments possible. Side cuffs help to keep the frame at the desired position from right to left. Indicators attached to the frame for the anterior fiducial plate prevent potential contact of the plate with the anterior posts and help avoid a poor fit caused by bending of the frame from excessive torque on the cranium fixation screws. Indicators for the MRI frame holder on the foot screws predict potential collision of the holder with the patient's shoulder before actually applying the holder on the frame. The applicator shows the range and limits of the Leksell stereotactic arc. This applicator system has been used effectively in more than 89 MRI-based functional stereotactic procedures. These include pallidotomy, thalamotomy, implantation of deep brain stimulators, and implantation of depth electrodes. It has functioned well and has facilitated excellent operative results in these cases. This simple frame applicator eliminates the need for reapplication of the stereotactic frame and additional imaging studies, thus providing successful and appropriate frame placement for stereotactic surgery.
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Incorporation of the first postgraduate year of training into neurological surgery residencies in 2009 posed new challenges to neurosurgical educators. A... more
Incorporation of the first postgraduate year of training into neurological surgery residencies in 2009 posed new challenges to neurosurgical educators. A "boot camp" course was held in August 2009 to introduce first year neurosurgical trainees to various fundamental cognitive and practical skills. The effectiveness of this course was evaluated by electronic survey of all trainees and faculty members. Eighteen trainees entering 5 western neurosurgical residencies (in either the first or second postgraduate year) participated in a course taught by 10 faculty members at a single host institution (Oregon Health & Science University) for 2 days. All trainees completed an online survey evaluating the relevance and quality of each didactic and hands-on course component and answered additional questions about the goals and design of the course. Faculty members were also surveyed. All trainees thought the course met its goals, provided relevant and useful information and experience, and was likely to improve patient care. In particular, hands-on procedural and operative course components were highly valued. A fundamental skills boot camp course for first year neurosurgical trainees seems valuable.
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Trigeminal neuropathic pain (TNP) after facial trauma or herpes zoster infection is often refractory to treatment. Peripheral nerve stimulation has been used to treat occipital neuralgia; however, efficacy in controlling facial TNP or... more
Trigeminal neuropathic pain (TNP) after facial trauma or herpes zoster infection is often refractory to treatment. Peripheral nerve stimulation has been used to treat occipital neuralgia; however, efficacy in controlling facial TNP or postherpetic neuralgia is unknown. A retrospective case series of patients who underwent subcutaneous placement of stimulating electrodes for treatment of V(1) or V(2) TNP secondary to herpetic infection or facial trauma is presented. Ten patients received implanted subcutaneous pulse generators and quadripolar electrodes for peripheral stimulation of the trigeminal nerve supraorbital or infraorbital branches. Long-term treatment results were determined by retrospective review of medical records (1998-2003) and by independent observers interviewing patients using a standard questionnaire. Surgical complication rate, preoperative symptom duration, degree of pain relief, preoperative and postoperative work status, postoperative changes in medication usage, and overall degree of therapy satisfaction were assessed. Mean follow-up was 26.6 +/- 4.7 months. Peripheral nerve stimulation provided at least 50% pain relief in 70% of patients with TNP or postherpetic neuralgia. Medication use declined in 70% of patients, and 80% indicated that they were mostly or completely satisfied with treatment overall. There were no treatment failures (<50% pain relief and a lack of decrease in medication use) in the posttraumatic group, and two failures (50%) occurred in the postherpetic group. The complication rate requiring reoperation was 30%. Peripheral nerve stimulation of the supraorbital or infraorbital branches of the trigeminal nerve is an effective method for relief of TNP after facial trauma or herpetic infection. A prospective trial using this novel approach to treat these disorders is thus warranted.
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OBJECT Lesioning of the dorsal root entry zone (DREZotomy) is an effective treatment for brachial plexus avulsion (BPA) pain. The role of preoperative assessment with MRI has been shown to be unreliable for determining affected levels;... more
OBJECT Lesioning of the dorsal root entry zone (DREZotomy) is an effective treatment for brachial plexus avulsion (BPA) pain. The role of preoperative assessment with MRI has been shown to be unreliable for determining affected levels; however, it may have a role in predicting pain outcomes. Here, DREZotomy outcomes are reviewed and preoperative MRI is examined as a possible prognostic factor. METHODS A retrospective review was performed of an institutional database of patients who had undergone brachial plexus DREZ procedures since 1995. Preoperative MRI was examined to assess damage to the DREZ or dorsal horn, as evidenced by avulsion of the DREZ or T2 hyperintensity within the spinal cord. Phone interviews were conducted to assess the long-term pain outcomes. RESULTS Between 1995 and 2012, 27 patients were found to have undergone cervical DREZ procedures for BPA. Of these, 15 had preoperative MR images of the cervical spine available for review. The outcomes were graded from 1 to...
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ABSTRACT
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To assess the value of high-resolution three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography and gadolinium (Gad)-enhanced 3D spoiled gradient-recalled imaging in the visualization of neurovascular compression in... more
To assess the value of high-resolution three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography and gadolinium (Gad)-enhanced 3D spoiled gradient-recalled imaging in the visualization of neurovascular compression in patients with trigeminal neuralgia. Forty-eight patients with unilateral trigeminal neuralgia underwent high-resolution 3D TOF MR angiography. After administration of a contrast agent, a 3D spoiled gradient-recalled sequence (3D Gad) was run. Images were reviewed by a radiologist blinded to clinical details. All patients underwent microvascular decompression surgery. Microdissection of the trigeminal nerve and compressing vessels was videotaped during surgery and reviewed by surgeons uninvolved in patient care. Results from neuroradiological studies were then compared with findings on operative videotapes. MR angiography in combination with 3D Gad imaging identified surgically verified neurovascular contact in 42 of 46 (91%) symptomatic nerves. The...
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When not corrected, geometrically distorted magnetic resonance images may be unsuitable for stereotactic intracranial neurosurgical procedures where accuracy of target localization is critical. On a GE Signa 1.5-tesla system, we... more
When not corrected, geometrically distorted magnetic resonance images may be unsuitable for stereotactic intracranial neurosurgical procedures where accuracy of target localization is critical. On a GE Signa 1.5-tesla system, we implemented an imaging protocol designed to improve the accuracy of the determination of target coordinates by means of multiple scans utilizing reversal of the frequency-encoded readout gradient. Using a Cosman-Roberts-Wells (CRW) frame and a phantom, geometric shifts of important image features were found to occur. In patients undergoing functional neurosurgical procedures with the CRW system, localization of the posterior commissure by corrected MR images was compared to that obtained by intraoperative ventriculography. Unexpectedly, severe distortions in MR images were revealed by the studies, with shifts of some fiducial markers of 10 mm from their estimated true position. Most of this distortion was attributable to the magnetic properties of the stereo...
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Research Interests: APS and Prospective Study
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Much has been written about the accomplishments of Walter E. Dandy, and he remains one of the seminal figures in neurosurgery. He is perhaps best known for his scientific contributions to our understanding of cerebrospinal fluid and... more
Much has been written about the accomplishments of Walter E. Dandy, and he remains one of the seminal figures in neurosurgery. He is perhaps best known for his scientific contributions to our understanding of cerebrospinal fluid and pituitary gland physiology and his clinical contributions of ventriculography, cerebellopontine angle approaches for a variety of posterior fossa pathology, and the first clipping of a cerebral aneurysm. What is not as well known is that Dandy was the first to accurately describe and treat lumbar disc herniation. He published a thorough clinical, operative, and pathological description in a 1929 Archives of Surgery article, titled "Loose Cartilage from Intervertebral Disk Simulating Tumor of the Spinal Cord." His publication predates by 5 years the well-known 1934 Mixter and Barr article "Rupture of the Intervertebral Disc with Involvement of the Spinal Canal."
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Epilepsy surgery can be an effective epilepsy treatment for patients whose seizures do not respond to best medical therapy. For patients with temporal lobe epilepsy, selective amygdalohippocampectomy (SAH) has emerged as a viable... more
Epilepsy surgery can be an effective epilepsy treatment for patients whose seizures do not respond to best medical therapy. For patients with temporal lobe epilepsy, selective amygdalohippocampectomy (SAH) has emerged as a viable alternative to standard anterior temporal lobectomy. This paper reviews the indications for SAH, the technical advances that have led to greater adoption of the procedure, the expectations for seizure control, and the risks of morbidity.
Stereotactic radiosurgery requires the highest degree of accuracy in target identification and localization. When targeting paraspinal lesions, the CyberKnife radiosurgical system (Accuray, Inc., Sunnyvale, CA) uses implanted stainless... more
Stereotactic radiosurgery requires the highest degree of accuracy in target identification and localization. When targeting paraspinal lesions, the CyberKnife radiosurgical system (Accuray, Inc., Sunnyvale, CA) uses implanted stainless steel fiducials. The purpose of this study was to evaluate the total system for clinically relevant accuracy of this approach. The clinically relevant accuracy of the CyberKnife depends on 1) the accuracy of beam delivery, which in turn represents a compilation of robot and camera image-tracking errors, and 2) the inherent accuracy of target localization that stems from computed tomographic imaging and treatment planning. The clinically relevant accuracy was measured at three different CyberKnife facilities using head and torso phantoms loaded with packs of radiochromic film and expressed as a displacement of the dose contours from the treatment planning. The mean clinically relevant error, as measured at three different CyberKnife facilities, was det...
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The goal of this study was to evaluate the efficacy of the transverse tripolar spinal cord stimulation system (TTS) in providing relief of low back pain in patients with chronic non-malignant pain. Transverse tripolar electrodes were... more
The goal of this study was to evaluate the efficacy of the transverse tripolar spinal cord stimulation system (TTS) in providing relief of low back pain in patients with chronic non-malignant pain. Transverse tripolar electrodes were implanted in the lower thoracic region (T(8-9) to T(12)-L(1)) in 10 patients with chronic neuropathic pain, all of whom reported a significant component of low back pain in combination with unilateral or bilateral leg pain. One patient reported inadequate pain relief during the trial and was not implanted with a permanent generator. A visual analogue scale of low back pain showed a nonsignificant decrease from 64 +/- 19 to 47 +/- 30 (p = 0.25; paired t test) after 1 month of stimulation. Similarly, functional disability evaluated using Oswestry Low Back Pain Questionnaire was not improved (p = 0. 46; paired t test). We conclude that chronic low back pain is not particularly responsive to the transverse stimulation provided by the TTS system.
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OBJECTIVE Primary closure of the dura remains difficult in many neurosurgical cases. One option for dural grafting is the collagen sponge, which is available in multiple forms, namely, monolayer collagen and bilayer collagen. Our primary... more
OBJECTIVE Primary closure of the dura remains difficult in many neurosurgical cases. One option for dural grafting is the collagen sponge, which is available in multiple forms, namely, monolayer collagen and bilayer collagen. Our primary goal was to assess differences in the incidence of postoperative cerebrospinal fluid (CSF) leak, including fistula and pseudomeningocele, and postoperative infection between monolayer collagen and bilayer collagen grafts. METHODS A single-center retrospective analysis of 475 consecutive neurosurgical procedures was performed. Primary endpoints were CSF leak and infection, adjusting for the impact of additional nonautologous materials. Multivariate regression analysis was used to identify predictors of postoperative CSF leak and infection. RESULTS The overall frequency of postoperative CSF leak was 6.7%. There was no significant difference in the incidence of CSF leak based on the type of collagen sponge (monolayer versus bilayer) used (5.5% versus 7...
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Research Interests: Cartography, Surgery, Pain, Treatment, Case Report, and 10 moreHumans, Male, Rhizotomy, Skin, Clinical Sciences, Middle Aged, Neurosciences, Forearm, Ulnar Nerve, and Macho
Distally propagating spontaneous impulses in acutely and chronically cut rat saphenous nerve were examined to determine (1) the origin(s) of the activity, (2) the fiber types involved, and (3) whether the activity was affected by... more
Distally propagating spontaneous impulses in acutely and chronically cut rat saphenous nerve were examined to determine (1) the origin(s) of the activity, (2) the fiber types involved, and (3) whether the activity was affected by potassium channel blockade. Under deep pentobarbital anesthesia, six male Sprague-Dawley rats underwent L3 cauda equina section, then unilateral saphenous axotomy. The nerve was then dissected into 30-50 microfilaments and surveyed for spontaneous activity using a modification of the microfilament recording method. Afterward, the nerve was cut back, and a potassium channel blocking agent (gallamine) was administered. The axonal activity was once again surveyed in the same fashion. Twenty-eight rats underwent unilateral saphenous axotomy 1-8 weeks prior to similar recordings, and the neuroma was excised just before microfilament dissection. Spontaneous discharges in these preparations originated from three foci: (1) antidromic activity from in-continuity dorsal root ganglia (DRG), (2) orthodromic activity from sympathetic neurons, and (3) antidromic activation of dichotomizing afferent axons in the peripheral nerve. There was significantly more antidromic activity from DRG in rats with prior axotomies than in control animals (t = 2.38; p less than 0.025), and gallamine produced a significant increase in DRG activity in the chronically lesioned nerve (t = 2.43; p less than 0.005), but not in acutely lesioned controls. However, most of the spontaneous activity in these preparations was from sympathetic efferents. This activity was decreased significantly by chronic axotomy (t = 2.635; p less than 0.01), and it was not affected by potassium channel blockade with gallamine. In two microfilaments, spontaneous antidromic action potentials were observed in conjunction with a clear receptive field on blood vessels in the nearby fascia. Both of these presumably dichotomized axons were found in acutely cut nerve, thus were not the result of retrograde sprouting from a neuroma. It was concluded that (1) chronic axotomy of sensory afferents produced ectopic activity in their respective DRG, (2) gallamine administration increased spontaneous activity from DRG in chronically axotomized rats, (3) ongoing sympathetic efferent activity in rat saphenous nerve was decreased by distal axotomy for up to 8 weeks, and (4) rare branched sensory afferents occasionally exhibit spontaneous activity.
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Previous studies of experimental neuromas have indicated that some axons terminating in the neuroma exhibit both spontaneous and mechanosensitive discharges. Since these spontaneous discharges appear to occur in potentially nociceptive... more
Previous studies of experimental neuromas have indicated that some axons terminating in the neuroma exhibit both spontaneous and mechanosensitive discharges. Since these spontaneous discharges appear to occur in potentially nociceptive axons (A delta and C fibers), it has been speculated that this activity may relate to pain that occurs after peripheral nerve injury. Recent results from our laboratory have revealed several possible sources of error in prior electrophysiological studies of neuromas. Most notably, gallamine, a muscle-paralyzing agent that has been used in the majority of previous studies of experimental neuromas, has profound potassium-channel-blocking properties that may increase spontaneous activity in damaged axons. The present study was conducted to re-evaluate the incidence of spontaneous activity in experimental neuromas, and the fiber types involved in these discharges. A group of 44 male Sprague-Dawley rats underwent unilateral saphenous axotomy 1-8 weeks prior to acute neurophysiological recording experiments, and 6 additional rats underwent acute control recording procedures only. Recording was performed in all animals using a modification of the microfilament recording technique to determine the conduction velocities (CVs) and origins of spontaneously discharging axons. A thorough search for spontaneous discharges was made in each nerve both before and after the administration of gallamine. Spontaneous activity was rare in acutely severed saphenous nerve and was not significantly affected by gallamine administration. In rats with 1- to 4-week-old experimental saphenous neuromas, spontaneous activity was rare but was increased by a factor of 12.75 after gallamine treatment. Gallamine administration produced significantly more of both A alpha beta and A delta activity, compared to control recordings. No spontaneous C-fiber activity was found originating in neuromas either before or after gallamine. C-fiber spontaneous discharges in the apparently isolated saphenous nerve segment had receptive fields in fascia, superficial vasculature, and hairy skin of the medial hindlimb. Our conclusions are as follows: (1) Neuromas exhibit only rare spontaneous discharges unless exposed to potassium-channel-blocking agents; (2) all C-fiber activity recorded in saphenous nerve with a distal neuroma is derived from vascular, fascial, and other receptive fields rather than from the neuroma; (3) these data are consistent with known clinical phenomena in that neuromas are not usually spontaneously painful.
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In animal neuroma models the application of alpha-adrenergic agonists causes a burst of spontaneous afferent activity. The increased activity has been hypothesized to generate nociceptive input. Corroborative work in humans, however, has... more
In animal neuroma models the application of alpha-adrenergic agonists causes a burst of spontaneous afferent activity. The increased activity has been hypothesized to generate nociceptive input. Corroborative work in humans, however, has not been done. Nine subjects with chronic nerve end neuromas received perineuromal injections of normal saline, epinephrine (5 micrograms), and lidocaine in a blinded manner. Qualitative and quantitative pain assessments were performed with each injection. Epinephrine, but not saline, caused an intense increase in reported pain with subjects often commenting that the appendage was "on fire". Lidocaine significantly reduced but did not completely abolish the reported pain. The chemosensitivity of the neuroma to epinephrine may explain some of the clinical responses noted after sympathetic system manipulation. It is likely that alpha-adrenergic sensitivity is only one of many components sustaining or exacerbating pain after nerve injury.
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For confirming the correct location of the radiofrequency electrode before creation of a lesion, percutaneous CT-guided trigeminal tractotomy–nucleotomy is most commonly performed with the patient prone and awake. However, for patients... more
For confirming the correct location of the radiofrequency electrode before creation of a lesion, percutaneous CT-guided trigeminal tractotomy–nucleotomy is most commonly performed with the patient prone and awake. However, for patients whose facial pain and hypersensitivity are so severe that the patients are unable to rest their face on a support (as required with prone positioning), awake CT-guided tractotomy-nucleotomy might not be feasible. The authors describe 2 such patients, for whom percutaneous intraoperative CT-guided tractotomy-nucleotomy under general anesthesia was successful. One patient was a 79-year-old man with profound left facial postherpetic neuralgia, who was unable to tolerate awake CT-guided tractotomy-nucleotomy, and the other was a 45-year-old woman with intractable hemicranial pain that developed after a right frontal lesionectomy for epilepsy. Each patient underwent a percutaneous intraoperative CT-guided tractotomy-nucleotomy under general anesthesia. No ...
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Modern neuronavigation systems lack spatial accuracy during ongoing surgical procedures because of increasing brain deformation, known as brain shift. Intraoperative magnetic resonance imaging was used for quantitative analysis and... more
Modern neuronavigation systems lack spatial accuracy during ongoing surgical procedures because of increasing brain deformation, known as brain shift. Intraoperative magnetic resonance imaging was used for quantitative analysis and visualization of this phenomenon. For a total of 64 patients, we used a 0.2-T, open-configuration, magnetic resonance imaging scanner, located in an operating theater, for pre- and intraoperative imaging. The three-dimensional imaging data were aligned using rigid registration methods. The maximal displacements of the brain surface, deep tumor margin, and midline structures were measured. Brain shift was observed in two-dimensional image planes using split-screen or overlay techniques, and three-dimensional, color-coded, deformable surface-based data were computed. In selected cases, intraoperative images were transferred to the neuronavigation system to compensate for the effects of brain shift. The results demonstrated that there was great variability in brain shift, ranging up to 24 mm for cortical displacement and exceeding 3 mm for the deep tumor margin in 66% of all cases. Brain shift was influenced by tissue characteristics, intraoperative patient positioning, opening of the ventricular system, craniotomy size, and resected volume. Intraoperative neuronavigation updating (n = 14) compensated for brain shift, resulting in reliable navigation with high accuracy. Without brain shift compensation, neuronavigation systems cannot be trusted at critical steps of the surgical procedure, e.g., identification of the deep tumor margin. Intraoperative imaging allows not only evaluation of and compensation for brain shift but also assessment of the quality of mathematical models that attempt to describe and compensate for brain shift.
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There are no randomized controlled trials comparing retrogasserian percutaneous radiofrequency thermocoagulation, glycerol rhizolysis, balloon compression of the gasserian ganglion, and stereotactic radiosurgery, nor are there systematic... more
There are no randomized controlled trials comparing retrogasserian percutaneous radiofrequency thermocoagulation, glycerol rhizolysis, balloon compression of the gasserian ganglion, and stereotactic radiosurgery, nor are there systematic reviews using predefined quality criteria. The objective of this study was to systematically identify all of the studies reporting outcomes and complications of ablative techniques for treatment of trigeminal neuralgia, from the development of electronic databases, and to evaluate them with predefined quality criteria. Inclusion criteria for the outcome analysis included thorough demographic documentation, defined diagnostic and outcome criteria, a minimum of 30 patients treated and median/mean follow-up times of 12 months, not more than 20% of patients lost to follow-up monitoring, Kaplan-Meier actuarial analysis of individual procedures, less than 10% of patients retreated because of failure or early recurrence, and a minimal dose of 70 Gy for stereotactic radiosurgery. High-quality studies with no actuarial analysis were used for the evaluation of complications. Of 175 studies identified, 9 could be used to evaluate rates of complete pain relief on a yearly basis and 22 could be used to evaluate complications. In mixed series, radiofrequency thermocoagulation offered higher rates of complete pain relief, compared with glycerol rhizolysis and stereotactic radiosurgery, although it demonstrated the greatest number of complications. Radiofrequency thermocoagulation offers the highest rates of complete pain relief, although further data on balloon microcompression are required. It is essential that uniform outcome measures and actuarial methods be universally adopted for the reporting of surgical results. Randomized controlled trials are required to reliably evaluate new surgical techniques.
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PURPOSE A patient-oriented classification scheme for facial pains commonly encountered in neurosurgical practice is proposed. CONCEPT This classification is driven principally by the patient's history. RATIONALE The scheme... more
PURPOSE A patient-oriented classification scheme for facial pains commonly encountered in neurosurgical practice is proposed. CONCEPT This classification is driven principally by the patient's history. RATIONALE The scheme incorporates descriptions for so-called “atypical” trigeminal neuralgias and facial pains but minimizes the pejorative, accepting that the physiology of neuropathic pains could reasonably encompass a variety of pain sensations, both episodic and constant. Seven diagnostic labels result: trigeminal neuralgia Types 1 and 2 refer to patients with the spontaneous onset of facial pain and either predominant episodic or constant pain, respectively. Trigeminal neuropathic pain results from unintentional injury to the trigeminal nerve from trauma or surgery, whereas trigeminal deafferentation pain results from injury to the nerve by peripheral nerve ablation, gangliolysis, or rhizotomy in an intentional attempt to treat either trigeminal neuralgia or other facial pain...
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We report the case of a 70-year-old man with a 17-year history of angina pectoris, who had previously suffered two documented myocardial infarctions and undergone multiple diagnostic cardiac catheterizations, two coronary artery bypass... more
We report the case of a 70-year-old man with a 17-year history of angina pectoris, who had previously suffered two documented myocardial infarctions and undergone multiple diagnostic cardiac catheterizations, two coronary artery bypass operations, and several percutaneous transluminal coronary angioplasty procedures. The patient had experienced unstable angina for the past 3 years refractory to maximal medical therapy and was unsuitable for further attempts at revascularization. After a successful trial of epidural infusion of morphine, a totally implantable programmable continuous-infusion device with an intrathecal catheter was implanted in the patient on August 18, 1993, resulting in maintained pain resolution. His gardening, carpentry, and other activities of daily living were limited only by shortness of breath. Six months later, the pump treatment did not mask the development of a myocardial infarction. To the best of our knowledge, this is the first report of the use of continuous intrathecal infusion of morphine or the use of a totally implantable programmable infusion device for angina pectoris. We propose that in carefully selected patients with chronic unstable angina, continuous intrathecal infusion of morphine may relieve effort-induced pain without resulting in myocardial infarction.
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Frameless stereotactic systems have become an integral part of neurosurgical practice. At our center, we recently introduced for clinical use a small, portable, frameless stereotactic system, namely the Cygnus PFS system (Compass... more
Frameless stereotactic systems have become an integral part of neurosurgical practice. At our center, we recently introduced for clinical use a small, portable, frameless stereotactic system, namely the Cygnus PFS system (Compass International, Rochester, MN). The purpose of this study was to compare the accuracy of the Cygnus PFS system with that of two larger systems that are also currently in use at our institution, i.e., the SMN system (Zeiss, Oberkochen, Germany) and the ISG viewing wand (ISG Technologies, Toronto, Canada). These systems represent three kinds of frameless stereotactic technologies that are commercially available. Each system uses a different method of spatial localization, i.e., mechanical linkage (ISG system), magnetic field digitization (Cygnus system), or optical technology (SMN system). Using a stereotactic "phantom," we measured the accuracies of all three systems with identical data sets. The errors in localization in three-dimensional space for nine targets were calculated by using 10 magnetic resonance imaging data sets. The precision of each system was also calculated. With this experimental protocol, the Cygnus system attained a mean accuracy of 1.90 +/- 0.7 mm, the ISG viewing wand system a mean accuracy of 1.67 +/-0.43 mm, and the SMN microscope a mean accuracy of 2.61 +/- 0.99 mm. The precision values were not significantly different among the systems. We observed only small differences in accuracy and precision among these three systems. We briefly review the advantages and disadvantages of each system and note that other factors, such as portability, ease of use, and microscope integration, should influence the selection of a frameless stereotactic system.
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To examine in a prospective manner the long-term safety and efficacy of chronic intrathecal morphine in patients with severe, nonmalignant pain refractory to less invasive modalities. Forty patients with severe, chronic nonmalignant pain... more
To examine in a prospective manner the long-term safety and efficacy of chronic intrathecal morphine in patients with severe, nonmalignant pain refractory to less invasive modalities. Forty patients with severe, chronic nonmalignant pain poorly managed by systemic medications were identified as candidates for intraspinal trial of morphine. Thirty participants reported successful pain relief during trial and were implanted with an intraspinal delivery system. Standardized measures of pain and functional status were assessed before treatment was begun and at defined intervals during the subsequent 24 months. Intrathecal opioid use and pharmacological and device-related complications were also monitored. The participants had a mean age of 58 +/- 13 years and a mean pain duration of 8 +/- 9 years. Fifty-three percent of the study participants were women. Pain type was characterized as mixed neuropathic-nociceptive (15 of 30 patients, 50%), peripheral neuropathic (10 of 30 patients, 33%), deafferentation (4 of 30 patients, 13%), or nociceptive (1 of 30 patients, 3%). Forty-seven percent of the patients were diagnosed with failed back surgery syndrome. Significant improvement over baseline levels of visual analog scale pain was measured at each follow-up examination after implant. Overall, 50% (11 of 22 patients) of the population reported at least a 25% reduction in visual analog scale pain after 24 months of treatment. In addition, the McGill Pain Questionnaire, visual analog scale measures of functional improvement and pain coping, and several subscales of the Chronic Illness Problem Inventory showed improvement throughout the follow-up period. Pharmacological side effects were managed medically by morphine dose reduction, addition of bupivacaine, or replacement of morphine with hydromorphone. Device-related complications requiring repeat operations were experienced by 20% of the patients. Continuous intrathecal morphine can be a safe, effective therapy for the management of severe, nonmalignant pain among a carefully selected patient population and can result in long-term improvement in several areas of daily function.