Honored guest presentation: therapeutic decisions in facial pain.

The authors recommend a multidisciplinary approach for the diagnosis and treatment of facial pain. With this approach, several experts can accurately diagnose various disorders of facial pain and offer appropriate treatment options, which should be tailored to the specific needs and general condition of the patient. For reporting and comparison, seek standardization of methods of analysis and outcomes criteria. Associate with a good secretary and nurse. For your patients' benefit, be an optimistic, caring, and attentive listener.

Outcome of unilateral and bilateral pallidotomy for Parkinson's disease: patient assessment.

OBJECTIVE: Pallidotomy has recently regained acceptance as a safe and effective treatment for Parkinson's disease symptoms. The goal of this study was to obtain the patients' perspective on their results after undergoing this procedure. Special attention was focused on the potential complications and the respective advantages and risks of unilateral versus bilateral pallidotomy. METHODS: Fifty-six patients were studied during a 2-year period; 44 completed the evaluation, with a median follow-up of 7 months. Of these patients, 22 underwent unilateral pallidotomy, and 17 had bilateral simultaneous pallidotomy. Five patients who underwent staged bilateral pallidotomy were excluded from the statistical analysis, because the number of patients was considered too small for analysis. The procedures were performed with magnetic resonance imaging determination of the target, combined with physiological confirmation, including microelectrode recording. RESULTS: According to Visual Analog Scale scores, unilateral pallidotomy significantly improved dyskinesias (P < 0.05) but no other symptoms. Simultaneous bilateral pallidotomy improved slowness, rigidity, tremor, and dyskinesias (P < 0.05) but worsened speech function (P < 0.05). According to the patients' most frequently chosen answers to multiple-choice questions, unilateral pallidotomy improved night sleep, muscle pain, freezing, overall "on," overall "off," and the duration of "off periods," but it worsened the volume of the voice and articulation, increased drooling, and reduced concentration. Bilateral pallidotomy improved night sleep, muscle pain, freezing, overall "on," overall "off," duration of "off periods," and the amount of medication taken, but it increased drooling and worsened the volume of the voice, articulation, and writing. Subjective visual disturbance was noted in 36 and 41% of patients who underwent unilateral and simultaneous bilateral pallidotomy, respectively. Globally, the result of the procedure was rated "good" or "excellent" by 64% of the patients who underwent unilateral pallidotomy and by 76% of the patients who underwent bilateral pallidotomy. An age less than 70 years was a positive prognostic factor for the global outcome (P < 0.05), as were severe preoperative dyskinesias (P < 0.05). CONCLUSION: This study confirms that, from a patient standpoint, unilateral and simultaneous bilateral pallidotomy can reduce all the key symptoms of Parkinson's disease (i.e., akinesia, tremor, and rigidity) and the side effects of L-dopa treatment (i.e., dyskinesias). Preoperative severe dyskinesias and younger age are positive prognostic factors for a successful outcome. Simultaneous bilateral pallidotomy was more effective than unilateral pallidotomy regarding tremor, rigidity, and dyskinesias, but it conferred a higher risk of postoperative speech deterioration.

Thalamic deep brain stimulation for the treatment of head, voice, and bilateral limb tremor.

OBJECT: In published series of patients who undergo deep brain stimulation (DBS) of the thalamus the effects of unilateral stimulation on contralateral limb tremor have been reported. The authors detail their experience with bilateral thalamic DBS in the treatment of head, voice, and bilateral limb tremor and compare it with earlier studies of unilateral stimulation. METHODS: Twenty-three patients (six with Parkinson's disease, 15 with essential tremor, and two with multiple sclerosis) underwent 19 bilateral DBS procedures (nine staged, 10 simultaneous) and four procedures contralateral to thalamotomy to control tremor of the head in 10, voice in seven, and limbs in 20 patients. Limb tremor improvement was graded as follows: 4, no tremor; 3, stress-induced tremor; 2, functional improvement; 1, no functional improvement; and 0, persistent tremor. Improvement of head or voice tremor was graded as follows: 4, greater than 75%; 3, between 50% and 75%; 2, between 25% and 50%; 1, less than 25%; and 0, no improvement. The mean follow-up period was 10 months. Twenty-two patients (96%) demonstrated improved tremor at the last follow-up review. Of 20 patients with bilateral limb tremor, 17 (85%) improved to Grades 3 and 4, two patients (10%) with multiple sclerosis improved to Grade 2, and one (5%) exhibited tremor recurrence 8 months later. Nine (90%) of 10 patients with severe head tremor improved to Grades 4 or 3. Six (86%) of seven patients with voice tremor improved to Grade 3. Seven patients (30%) developed dysarthria, and seven (30%) developed disequilibrium; symptoms reversed in the majority of patients after the stimulation parameters were changed. One patient (4%) developed mild memory decline. There were no deaths. CONCLUSIONS: The following findings are reported: 1) bilateral thalamic DBS and stimulation contralateral to thalamotomy are safe; 2) staging the procedure does not reduce the risk of dysarthria or gait disequilibrium; and 3) head and voice tremor are primary indications for bilateral DBS.

Computer analysis of the tonic, phasic, and kinesthetic activity of pallidal discharges in Parkinson patients.

OBJECTIVE: Intraoperative analysis of microrecording data during pallidotomy often depends on subjective interpretation of the oscilloscope signal, especially during the analysis of phasic activity. The goals of this project were: 1) to develop an inexpensive system that allowed on-line, objective characterization of single-unit pallidal discharges, and 2) to have objective criteria to differentiate the internal part (GPi) from the external part (GPe) of the globus pallidus. METHODS: A computer program was developed that allowed the analysis of firing rates (mean, median, and quartiles), spike count per unit time, and interspike interval (ISI) histograms with Chi-square statistical evaluation. Indices were developed that measured phasic activity, including burst index (BI) for the measurement of bursts, pause index (PI) for the measurement of pauses, and pause ratio (PR) for analysis of time spent in pauses. Single-unit activity of 152 GPe and 203 GPi cells in 47 Parkinson patients were digitized using the computer soundcard during pallidotomy and analyzed using this software. RESULTS: GPe discharges had a mean firing rate = 42 Hz, BI = 0.81, PI = 0.21, and PR = 1.41. GPi had a mean firing rate = 81, BI = 1.61, PI = 0.04, and PR = 0.21. The PR was the best index that differentiated GPe from GPi, followed by PI, BI, and firing rates, in that order. Kinesthetic cells were recorded equally in GPe from GPi, and their responses to generalized movements were not significantly different. CONCLUSION: (1) Signal analysis using the digitization process of a computer sound card and dedicated software is satisfactory for the objective "on-line" and "off-line" analysis of microrecordings (including phasic activity); (2) PI and PR are most helpful in differentiating neurons of GPi from those of GPe; (3) no single parameter can differentiate GPe from GPi activity in all cases; and (4) unlike the findings in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys, GPe and GPi of Parkinson patients have similar prevalence of kinesthetic cells and similar responses to generalized somatotopic effects.

Tremor control after pallidotomy in patients with Parkinson's disease: correlation with microrecording findings.

The goals of this study were to analyze the effect of pallidotomy on parkinsonian tremor and to ascertain whether an association exists between microrecording findings and tremor outcome. Forty-four patients with Parkinson's disease who had drug-induced dyskinesia, bradykinesia, rigidity, and tremor underwent posteroventral pallidotomy. Using a 1-mu-tip tungsten electrode, microrecordings were obtained through one to three tracts, starting 10 mm above the pallidal base. Tremor severity was measured on a patient-rated, 100-mm Visual Analog Scale (VAS), both preoperatively and 3 to 9 months (mean 6 months) postoperatively. Preoperatively, tremor was rated as 50 mm or greater in 24 patients (55%) and as less than 25 mm in 13 patients (30%). Postoperatively, tremor was rated as 50 mm or greater in five patients (11%) and less than 25 mm in 29 patients (66%). The difference was significant (p = 0.0001). Four patients (9%) had no postoperative tremor. Tremor improved by at least 50% in eight (80%) of 10 patients in whom tremor-synchronous cells were recorded (Group A) and in 12 (35%) of 34 patients in whom tremor-synchronous cells were not recorded (Group B). This difference was significant (p = 0.03). Tremor improved by at least 50 mm in all (100%) of the seven Group A patients with severe (> or = 50 mm) preoperative tremor and in nine (53%) of 17 Group B patients with severe preoperative tremor. This difference was also significant (p = 0.05). The authors prefer two conclusions: 1) after pallidotomy, tremor improves by at least 50% in two-thirds of patients with Parkinson's disease who have severe (> or = 50 mm on the VAS) preoperative tremor; and 2) better tremor control is obtained when tremor-synchronous cells are included in the lesion.

Tremor control after pallidotomy in patients with Parkinson's disease: correlation with microrecording findings.

The goals of this study were to analyze the effect of pallidotomy on parkinsonian tremor and to ascertain whether an association exists between microrecording findings and tremor outcome. Forty-four patients with Parkinson's disease (PD) who had drug-induced dyskinesia, bradykinesia, rigidity, and tremor underwent posteroventral pallidotomy. Using a 1-micro-tip tungsten electrode, microrecordings were obtained through one to three tracts, starting 10 mm above the pallidal base. Tremor severity was measured on a patient-rated, 100-mm Visual Analog Scale (VAS), both preoperatively and 3 to 9 months (mean 6 months) postoperatively. Preoperatively, tremor was rated as 50 mm or greater in 24 patients (55%) and as less than 25 mm in 13 patients (30%). Postoperatively, tremor was rated as 50 mm or greater in five patients (11%) and less than 25 mm in 29 patients (66%). The difference was significant (p = 0.0001). Four patients (9%) had no postoperative tremor. Tremor improved by at least 50% in eight (80%) of 10 patients in whom tremor-synchronous cells were recorded (Group A) and in 12 (35%) of 34 patients in whom tremor-synchronous cells were not recorded (Group B). This difference was significant (p = 0.03). Tremor improved by at least 50 mm in all (100%) of the seven Group A patients with severe (> or = 50 mm) preoperative tremor and in nine (53%) of 17 Group B patients with severe preoperative tremor. This difference was also significant (p = 0.05). The authors proffer two conclusions: 1) after pallidotomy, tremor improves by at least 50% in two-thirds of patients with PD who have severe (> or = 50 mm on the VAS) preoperative tremor; and 2) better tremor control is obtained when tremor-synchronous cells are included in the lesion.

Treatment of trigeminal neuralgia by percutaneous radiofrequency rhizotomy.

Percutaneous radiofrequency rhizotomy (PSR) is recognized as a simple, effective, and safe surgical treatment for trigeminal neuralgia. Rates of pain recurrence after PSR are the lowest versus those of other percutaneous procedures, and similar to those of microvascular decompression.

Infrequent types of pallidal discharges during pallidotomy.

Pallidal discharges of patients with Parkinson's disease have been characterized as slow irregular or bursting discharges for the external pallidal segment (GPe) and fast discharges for the internal pallidal segment (GPi). Tremor-synchronous cells have also been described. Using microrecording techniques on 70 patients who underwent pallidotomy, we have recorded other types of pallidal discharges. In GPe, we recorded cells which fired fast, cells which were silent, and cells which fired tonically. In GPi, we recorded cells which burst following short segments of fast tonic discharges. We will demonstrate these cells and discuss their clinical significance.

Functional anatomy of the pallidal base in Parkinson's disease.

OBJECTIVE: The purpose of this study is to define the morphology of the boundary between the globus pallidus and the ansa lenticularis (i.e., pallidal base) in humans. This information is important for surgeons who perform pallidotomy. METHODS: Thirty-eight patients with Parkinson's disease underwent pallidotomy using microrecording techniques. The pallidal base was identified by the loss of neuronal single unit activity and by the change in background noise, as analyzed on the audio monitor and by fast Fourier transformation. RESULTS: Three quarters of the patients had an abrupt transition of the background noise from neuronal to axonal activity. One quarter of the patients had multiple successive transitions of the background activity, over a distance of 0.4 to 2 mm (median, 1 mm). CONCLUSION: We conclude that the pallidal base is not a smooth, sharp boundary between the globus pallidus and the ansa lenticularis. We propose two models that define the morphology of the pallidal base. One model depicts the pallidal base as a multifolded boundary that distinctly separates pallidal neurons from ansa lenticularis axons. Another model depicts the pallidal base as an indistinct transitional boundary between the globus pallidus and the ansa lenticularis, which contains axonal fibers intermixed with small clusters of pallidal neurons. We discuss the clinical relevance of these findings.

Characteristics and somatotopic organization of kinesthetic cells in the globus pallidus of patients with Parkinson's disease.

Information is limited on the characteristics and topographic localization of pallidal kinesthetic cells in patients with Parkinson's disease. The authors analyzed the data from 298 neurons recorded in 38 patients with Parkinson's disease who underwent pallidotomy via microrecording techniques. Sixty-five neurons (22%) responded to passive movement of contralateral limbs. Of 17 kinesthetic cells that were tested in six patients, seven (41%) responded to ipsilateral limb movement as well. Nineteen cells (6%) fired synchronously with tremor. More kinesthetic cells were activated (63%) than inhibited (28%) by movement of single (68%) rather than multiple (32%) joints, and proximal (75%) rather than distal (25%) joints. The lateral globus pallidus externus (GPe) and medial globus pallidus internus (GPi) pallidal segments contained similar proportions of kinesthetic cells, activated or inhibited cells, arm- or leg-activated cells, and cells responding to single or multiple joints. Significantly more kinesthetic cells that responded to distal joints were recorded in GPi compared to GPe segments (p = 0.01). Arm and leg cells had similar characteristics pertaining to activation versus inhibition and responses to single, multiple, proximal, or distal joint movements. Arm and leg cells were somatotopically organized in GPi. Arm cells were clustered at the rostral and caudal segments of GPi and leg cells were clustered centrally. In GPe, leg cells were clustered at the caudal border. No somatotopic organization was identified for activated or inhibited cells; cells that responded to single, multiple, proximal, or distal joints; tremor-synchronous cells; or cells responding to specific joints within somatotopic arm or leg cells. It is concluded that kinesthetic cells provide a roadmap that localizes limb cells during pallidotomy. More studies are needed to identify the clinical significance of the different characteristics of kinesthetic cells.

Anchoring of deep brain stimulation electrodes using a microplate. Technical note.

The authors report a new technique to anchor deep brain stimulation electrodes using a titanium microplate. This technique has been safely used to secure 20 quadripolar deep brain stimulation electrodes implanted for movement disorders (18 electrodes) and pain (two electrodes). Twelve electrodes were implanted in the thalamus, four in the subthalamic nucleus, and four in the pallidum. No electrode migration or rupture occurred, and all electrodes have been shown to work properly after internalization of the system.

Pallidotomy: a survey of current practice in North America.

Twenty-eight centers completed a survey about their current practice of pallidotomy. This sample represents a non-exhaustive survey of the current practice of pallidotomy in North America and is not a study of outcomes. 1015 patients underwent 1219 pallidotomies: 811 (80%) unilateral, 72 (7%) staged bilateral, and 132 (13%) simultaneous bilateral. Pallidotomy has long been an accepted procedure and the indications for this surgery, in the opinion of the responding centers, were rated on a scale of 1 (poor) to 4 (excellent) and demonstrated dyskinesia as the best indication (median = 4); on-off fluctuations, dystonia, rigidity, and bradykinesia as good indications (median = 3); and freezing, tremor and gait disturbance as fair indications (median = 2). Most centers used MRI alone (50%) or in combination with CT scan (n = 6) or ventriculopathy (n = 5) to localize the target. The median values of pallidal coordinates were: 2 mm anterior to the midcommissural point 21 mm lateral to the midsagittal plane and 5 mm below the intercommissural line. Microrecording was performed by half of the centers (n = 14) and half of the remaining centers were considering starting it (n = 7). Main criteria used to define the target included the firing pattern of spontaneous neuronal discharges (n = 13) and the response to joint movement (n = 10). Most centers performed motor (n = 26) and visual (n = 23) macrostimulation. Twenty four centers performed test lesions using median values of 55 degrees C temperatures for 30 s. Final lesions consisted of 3 permanent lesions placed 2 mm apart, each lesion created with median values of 75 degrees C temperatures for 1 minute. Median hospital stay was 2 days.

Comparison of surgical treatments for trigeminal neuralgia: reevaluation of radiofrequency rhizotomy.

In this study, we reevaluate the results of radiofrequency rhizotomy and review the effectiveness of other surgical procedures for the treatment of trigeminal neuralgia. Five hundred patients with trigeminal neuralgia underwent radiofrequency rhizotomy at the University of Cincinnati Medical Center, Cincinnati, OH, between 1981 and 1986. Their results are compared with those of patients reported in the literature who underwent radiofrequency rhizotomy (6205 patients), glycerol rhizotomy (1217 patients), balloon compression (759 patients), microvascular decompression (MVD) (1417 patients), and partial trigeminal rhizotomy (250 patients). Comparisons were based on the following outcome parameters: technical success, pain relief and recurrence, facial numbness, dysesthesia, corneal anesthesia, keratitis, trigeminal motor dysfunction, permanent cranial nerve deficit, intracranial hemorrhage or infarction, perioperative morbidity, and perioperative mortality. We found that MVD had the lowest rate of technical success. Radiofrequency rhizotomy and MVD had the highest rates of initial pain relief and the lowest rates of pain recurrence. Glycerol rhizotomy had the highest rate of pain recurrence. Balloon compression had the highest rate of trigeminal motor dysfunction. Balloon compression and MVD had the lowest rates of corneal anesthesia or keratitis. MVD had the lowest rates of facial numbness and dysesthesia. All percutaneous procedures had similar rates of dysesthesia. Posterior fossa exploration had the highest rates of permanent cranial nerve deficit, intracranial hemorrhage or infarction, and perioperative morbidity and mortality. On the basis of our experience and a review of the literature, we conclude the following: 1) percutaneous techniques and posterior fossa exploration offer advantages and disadvantages, 2) radiofrequency rhizotomy is the procedure of choice for most patients undergoing first surgical treatments, and 3) MVD is recommended for healthy patients who have isolated pain in the first ophthalmic trigeminal division or in all three trigeminal divisions and patients who desire no sensory deficit.

A method to reduce systematic spatial shift associated with magnetic resonance imaging.

To reduce the chemical shifts during magnetic resonance (MR) imaging, the authors replaced the petroleum gel in the Brown-Roberts-Well (BRW) MR localizer with chromium chloride. Computed tomography and MR scans were obtained of a phantom skull containing objects with known spatial coordinates. A 2-to 3-mm systematic spatial shift in the frequency-encoded direction was observed with petroleum gel, but not with CrCl3. Results were verified by reconstructing the three-dimensional spatial location of each object using X-Knife computer software. The authors conclude that spatial localization is more accurate with a CrCl3-filled than a petroleum-filled BRW-MR localizer.

A prospective 15-year follow up of 154 consecutive patients with trigeminal neuralgia treated by percutaneous stereotactic radiofrequency thermal rhizotomy.

There is a lack of prospective studies for the long-term results of percutaneous stereotactic radiofrequency rhizotomy (PSR) in the treatment of patients with trigeminal neuralgia. The authors present results in 154 consecutive patients with trigeminal neuralgia treated by PSR and prospectively followed for 15 years. Ninety-nine percent of the patients obtained initial pain relief after one PSR. Dysesthesia occurred in 31 patients (23%): in 7% with mild initial hypalgesia; in 15% with dense hypalgesia; and in 36% with analgesia. Dysesthesia was mild and did not require treatment in most patients. The corneal reflex was absent or depressed in 29 patients, and keratitis developed in three patients. In 19 of 22 patients with trigeminal motor weakness, the paresis resolved within 1 year. Of 33 patients who had pain recurrence, 10 patients had pain that was mild or controlled with medications, and 23 patients required additional surgical treatment. The authors estimated using Kaplan-Meier analysis that the 14-year recurrence rate was 25% in the total group: 60% in patients with mild hypalgesia, 25% in those with dense hypalgesia, and 20% in those with analgesia. Timing of pain recurrence varied according to the degree of sensory loss. All pain recurrences in patients with mild hypalgesia occurred within 4 years after surgery; 10% more of the patients with dense hypalgesia had pain recurrences within the first 10 years compared with patients with analgesia. The median pain-free survival rate was 32 months for patients with mild hypalgesia and more than 15 years for patients with either analgesia or dense hypalgesia. Of the 100 patients followed for 15 years after one or two PSR procedures, 95 patients (95%) rated the procedure excellent (77 patients) or good (18 patients). The authors conclude that PSR is an effective, safe treatment for trigeminal neuralgia. Dense hypalgesia in the painful trigger zone, rather than analgesia, should be the target lesion.

Proximal-to-distal facial amplitude ratios as predictors of facial nerve function after acoustic neuroma excision.

Electrophysiological studies (for example, electroneuronography, nerve action potentials, absolute amplitudes of the muscle compound action potentials, and stimulation thresholds) do not accurately predict facial nerve function after the excision of acoustic neuromas. To eliminate individual nerve variability, the authors measured the ratio of the amplitudes of muscle compound action potentials produced by stimulating the facial nerve at the brainstem proximally and at the internal auditory meatus near the transverse crest distally after total tumor excision in 20 patients. The mean tumor size was 36 mm. The facial nerves were anatomically intact in all patients after tumor excision. The follow-up period ranged from 14 to 28 months. Facial nerve outcome was determined by a modified House-Brackmann grading scale. Initial facial nerve function was measured at Days 4 to 7 postoperatively, and final function was the grade at last follow up. The following results were obtained: all patients with proximal-to-distal amplitude ratios greater than 2:3 had Grade III or better initial function and Grade I final facial nerve function; 90% of patients with amplitude ratios between 1:3 and 2:3 had Grade III or worse initial facial nerve function, and 100% of these patients had Grade III or better final facial nerve function; all patients with amplitude ratios less than 1:3 had Grade IV or worse initial and final facial nerve function. The authors conclude that the proximal-to-distal amplitude ratios after acoustic neuroma excision can accurately predict postoperative facial nerve function.

Comparison of conventional and skull base surgical approaches for the excision of trigeminal neurinomas.

Trigeminal neurinomas have traditionally been excised through conventional approaches. Because symptomatic tumor recurrence exceeds 50% after conventional procedures, the authors evaluated the use of skull base approaches to achieve complete resection and a lower rate of symptomatic recurrence. Comparisons of skull base with conventional approaches to trigeminal neurinomas have been limited to small series with short-term follow-up periods. The authors reviewed their experiences with conventional (frontotemporal transsylvian, subtemporal-intradural, subtemporal-transtentorial, and suboccipital) and skull base (frontotemporal extradural-intradural, frontoorbitozygomatic, subtemporal anterior petrosal, and presigmoid posterior petrosal) surgical approaches for the excision of trigeminal neurinomas. In this paper they report the results of 15 patients with trigeminal neurinoma who underwent 27 surgical procedures between 1980 and 1990. Seventeen of the procedures used conventional and 10 used skull base approaches. All patients had tumors arising from Meckel's cave and the porus trigeminus either initially or on recurrence. Tumors located in the cavernous sinus recurred most frequently (83%); other tumors that recurred frequently were those located in Meckel's cave and the porus trigeminus (67%), and the posterior fossa (17%). The tumor extended into the anterolateral wall of the cavernous sinus in 38% of patients with cavernous sinus involvement. Tumor exposure and ease of dissection were superior with skull base approaches. Residual or recurrent tumors were found in 65% of patients following conventional approaches compared with 10% of patients following skull base approaches. Using skull base approaches, the surgeon was more accurate (90%) in estimating tumor excision than when using conventional approaches (43%). Perioperative complications were similar with both. The authors discuss the indications, advantages, and limitations of each approach. Based on anatomical considerations, they propose a strategy to best resect these tumors.