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Biomedical subjects

R E Wharen

Publications and source records attributed to R E Wharen.

At least 19 recordsLinked to original sources
PubMed2005

Bilateral thalamic deep brain stimulation: midline tremor control.

OBJECTIVES: To determine the efficacy of bilateral deep brain stimulation (DBS) for management of midline tremor (head, voice, tongue, trunk) in patients with essential tremor. DESIGN: Prospective assessment of tremor at baseline (presurgical), and postoperatively at 1, 3, and 12 months, and annually thereafter. METHODS: A clinical series of 22 individuals undergoing staged, bilateral DBS for treatment of essential tremor. The tremor rating scale was the primary outcome measure. RESULTS: Midline tremor showed significant improvement with stimulation "on" at nearly every postoperative interval when compared with stimulation "off" and with baseline tremor. Bilateral stimulation was associated with a significant incremental improvement in midline tremor control compared with unilateral stimulation: average "stimulation on" percentage change in midline tremor from the unilateral to bilateral period was 81%. Head and voice tremor showed the most consistent improvement. Among those requiring a change in stimulation parameters because of side effects, dysarthria, disequilibrium, motor disturbances, and paraesthesiae were the most common. Dysarthria was more common with bilateral (n = 6; 27%) than with unilateral (n = 0) stimulation. Stimulation parameters remained largely unchanged after the first three months. Nine of 44 leads placed (20%) required subsequent repositioning or replacement. CONCLUSIONS: Unilateral thalamic stimulation significantly improves midline tremor, and subsequent bilateral thalamic stimulation offers an additional incremental improvement in midline tremor control.

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PubMed2004

Thalamic deep brain stimulation for essential tremor: recommendations for long-term outcome analysis.

OBJECTIVES: Determine the efficacy of thalamic deep brain stimulation (DBS) for tremor control among individuals with essential tremor (ET). METHODS: A clinical series of 52 consecutive individuals undergoing placement of a DBS system for treatment of ET completed an unblinded battery of subjective and objective measures at postoperative intervals of one, three, and 12 months, and annually thereafter up to three years. The assessment battery included measures of tremor and activities of daily living. RESULTS: Both subjective and objective measures showed that stimulation was associated with significant improvement at nearly every postoperative interval as compared to pre-operative and stimulation 'off' ratings of activities of daily living functioning, midline tremor, contralateral upper extremity tremor, and contralateral lower extremity tremor. Ipsilateral tremor showed some improvement with stimulation, but only within the first three months. Trend analysis showed stable tremor control. Stimulation settings remained largely unchanged after the first three months. Dysarthria was more common among those with bilateral stimulation. A range of missing data estimation methods were performed, and subsequent analyses corroborated the main findings of the study. CONCLUSION: Thalamic DBS is generally a well-tolerated and effective treatment for ET. Methodological and analytical recommendations are provided for the evaluation of long-term outcome.

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PubMed2003

Thalamic deep brain stimulation for tremor-predominant Parkinson's disease.

OBJECTIVES: Determine the long-term efficacy of thalamic deep brain stimulation (DBS) for treatment of tremor among individuals with tremor-predominant Parkinson's disease (PD).Design. Longitudinal, unblinded assessment of tremor and activities of daily living (ADL) at baseline (pre-surgical), and post-operative intervals of 1, 3, and 12 months, and annually thereafter up to 3 years. METHODS: A clinical series of 19 individuals undergoing placement of a DBS system for treatment of PD-related tremor. A battery of subjective and objective measures of tremor was completed at planned pre- and post-operative intervals. RESULTS: Stimulation was associated with significant improvement on subjective and objective measures of ADL performance, midline tremor, and contralateral upper and lower extremity tremor, including parkinsonian resting and action tremors, over the follow-up period. Ipsilateral tremor showed little or no effect of stimulation after the first 3 months. Antiparkinsonian medication use and stimulation parameters showed little or no change over the course of follow-up. About half (53%) of all individuals reported at least one side effect, generally mild, during the follow-up period, with paresthesias and dysarthria being the most common. A total of two leads required replacement due to (1) infection, and (2) adverse side effects (i.e. burning and tingling with stimulation). CONCLUSION: DBS is associated with stable tremor control in PD. Side-effects are typically easily managed with stimulation adjustments, although in some cases lead replacement may be required.

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PubMed2001

Quantitative and qualitative outcome measures after thalamic deep brain stimulation to treat disabling tremors.

OBJECTIVE: We studied outcome measures after unilateral and bilateral thalamic stimulation to treat disabling tremor resulting from essential tremor and Parkinson's disease. The surgical technique, qualitative and quantitative tremor assessments, stimulation parameters, locations of active electrodes, complications, and side effects are described and analyzed. METHODS: Forty-one patients with essential tremor or Parkinson's disease underwent implantation of 56 thalamic stimulators. Preoperative qualitative and quantitative tremor measurements were compared with those obtained after unilateral and bilateral surgery, with activated and deactivated stimulators. Stimulation parameters and stimulation-related side effects were recorded, and outcome measures were statistically analyzed. RESULTS: Qualitative measurements demonstrated significant improvement of contralateral upper-limb (P < 0.001), lower-limb (P < 0.01), and midline (P < 0.001) tremors after unilateral surgery. Ipsilateral arm tremor also improved (P < 0.01). No differences were observed with the Purdue pegboard task. Quantitative accelerometer measurements were correlated with qualitative assessments and confirmed improvements in contralateral resting (P < 0.001) and postural (P < 0.01) tremors and ipsilateral postural tremor (P < 0.05). Activities of daily living improved after unilateral surgery (P < 0.001) and additionally after bilateral surgery (P < 0.05). Adjustments of the pulse generator were required more frequently for tremor control than for amelioration of side effects. Bilateral thalamic stimulation caused more dysarthria and dysequilibrium than did unilateral stimulation. Stimulation-related side effects were reversible for all patients. Stimulation parameters did not change significantly with time. A significantly lower voltage and greater pulse width were used for patients with bilateral implants. CONCLUSION: Unilateral thalamic stimulation and bilateral thalamic stimulation are safe and effective procedures that produce qualitative and quantitative improvements in resting, postural, and kinetic tremor. Thalamic stimulation-related side effects are mild and reversible.

Activities of Daily Living↗
PubMed2001

Simultaneous thalamic deep brain stimulation and implantable cardioverter-defibrillator.

Thalamic deep brain stimulation is becoming increasingly popular for the control of drug-refractory tremor. Implantable cardiac pacemakers and defibrillators are commonly used therapeutic modalities. Concerns exist about the potential interactions between these 2 devices in the same patient, but no experience has been reported previously. We describe a patient with essential tremor who had a deep brain stimulator implanted into the left ventral intermediate nucleus of thalamus, who subsequently needed an implantable cardioverter-defibrillator. Despite concerns about possible interactions between the 2 types of implanted electrical devices (i.e., a situation similar to drug-drug interactions), the deep brain stimulator and the implanted pacemaker-defibrillator functioned appropriately, and no interaction occurred in our patient.

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PubMed2000

Thalamic stimulation for the treatment of midline tremors in essential tremor patients.

The authors prospectively collected unblinded data from 27 consecutive patients following thalamic stimulation. A significant reduction of midline tremor was achieved after unilateral surgery, but a staged contralateral surgery had an additional effect. A subgroup analysis showed significant beneficial effects for head, voice, tongue, and face tremor. The most frequent reversible side effects were disequilibrium, dysarthria, and paresthesias. We observed more pulse generator adjustments for speech problems in the bilaterally implanted group.

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PubMed2000

Neuropsychological functioning in a patient with essential tremor with and without bilateral VIM stimulation.

The effects of deep brain stimulation on motor functions, cognitive abilities, and mood were assessed in an 80-year-old, right-handed male with a chronic history of essential tremor. Electrodes were implanted bilaterally in the ventral intermediate nucleus of the thalamus during a single operation. Upon evaluation at 3 months postsurgery, bilateral stimulation was associated with a clinically significant reduction in tremor ratings and improvement in manual dexterity. At that time, a battery of neuropsychological measures was administered with and without bilateral stimulation. The patient demonstrated comparable performances on measures of visuospatial perception, attention, mental tracking, verbal learning, and verbal recognition memory in both the "on" and "off" conditions. Without stimulation, the patient demonstrated declines of greater than 1 SD on measures of verbal fluency and verbal recall compared to when the stimulators were active. Responses to mood rating scales also indicated greater subjective distress without stimulation. Results are discussed in the context of previous studies of the effects of thalamic stimulation on neurocognitive functioning.

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PubMed2000

Hemangioma of the mandibular branch of the trigeminal nerve in the Meckel cave presenting with facial pain and sixth nerve palsy.

In a 25-year-old woman with episodic periorbital-temporal pain who eventually developed a sixth nerve palsy, magnetic resonance imaging revealed a lesion predominantly in the Meckel cave that was found to be a capillary hemangioma arising from the mandibular division of the trigeminal nerve. Hemangiomas of the Meckel cave must be considered in cases of facial pain with a sixth nerve palsy. even if there are no clinical findings of trigeminal neuropathy.

Abducens Nerve Diseases↗
PubMed2000

Predictors of neuropsychological outcome in patients following microelectrode-guided pallidotomy for Parkinson's disease.

OBJECT: The authors studied neuropsychological performance following microelectrode-guided posteroventral pallidotomy in patients with Parkinson's disease (PD) and evaluated correlations with presurgical and surgical factors. METHODS: Neuropsychological changes 3 months (43 patients) and 12 months (27 patients) after microelectrode-guided pallidotomy for PD are reported in a series of 44 consecutive patients with the disease, who improved neurologically, as measured by the Unified Parkinson's Disease Rating Scale (UPDRS) in both the "off' (p<0.001) and best "on" (p<0.001) states. Findings of the vocabulary subtest of the Wechsler Adult Intelligence Scale-Revised (p<0.01), Letter Fluency (p<0.001), Verbal Fluency for semantic categories (p<0.001), and the Wisconsin Card Sorting Test (p<0.01) showed a significant decline in neuropsychological performance in patients 3 months after undergoing left-sided pallidotomy. Impairment in the language domain (semantic fluency) persisted at the 12-month follow-up examination (p<0.01). Visual memory improved after right-sided pallidotomies (p<0.01 after 3 months), with a nonsignificant trend toward persistent improvement 1 year postsurgery (p<0.02 after 12 months). Preoperative semantic fluency was influenced by patient age (p<0.001) and by the width of the third ventricle (p<0.05), as measured by magnetic resonance imaging. A regression model revealed that semantic fluency 3 months postoperatively was significantly affected by the baseline score (p<0.001), side of surgery (p<0.001), handedness (p<0.01), and patient age (p<0.05). However, postoperative lesion volume, lesion location, number of tracks, number of lesions, distance from anatomical landmarks, or UPDRS score did not significantly contribute to neuropsychological outcome. CONCLUSIONS: Neuropsychological changes in a cohort of patients with PD who underwent pallidotomy and experienced excellent clinical benefits and minimum postoperative complications, emphasize the importance of neuropsychological examinations and further investigation of predictive factors.

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PubMed2000

Surgical evaluation and management of lumbar synovial cysts: the Mayo Clinic experience.

OBJECT: The authors report a retrospective analysis of 194 patients surgically treated at their institutions for symptomatic lumbar synovial cysts from January 1974 to January 1996. METHODS: Patient characteristics including age, sex, symptoms, signs, and preoperative neuroimaging studies were reviewed. Surgical procedures, complications, results, and pathological findings were correlated with preoperative assessment. One hundred ninety-four patients were surgically treated for symptomatic lumbar synovial cysts. Eighty percent were diagnosed and treated between 1987 and 1996. There were 100 men and 94 women with an average age of 66 years (range 28-94 years). The most common symptoms were painful radiculopathy (85%) and neurogenic single or multiroot claudication (44%). However, sensory loss (43%) and motor weakness (27%) were also presenting symptoms. Eleven percent of patients had undergone previous lumbar surgery prior to being referred to the Mayo Clinic. Preoperative neurological examination demonstrated motor weakness (40%), sensory loss (45%), reflex changes (57%), and variants of cauda equina syndrome (13%). In 19% of patients, normal neurological status was demonstrated. There was equal left/right-sided laterality, and eight patients presented with bilateral synovial cysts. The most commonly affected level was L4-5 (64%). All patients underwent laminectomy and resection of the cyst. Concomitant fusion was performed in 18 patients in whom clinical evidence of instability had been observed. However, subsequent fusion was required in only four patients who developed symptomatic spondylolisthesis. Surgery-related complications included cerebrospinal fluid leak (three patients), discitis (one patient), epidural hematoma (one patient), seroma (one patient), and deep vein thrombosis (one patient). One patient died 3 days after surgery of cardiac dysrhythmia. Follow-up data obtained for at least 6 months postoperatively were available in 147 patients. Of these, 134 (91%) reported good relief of their pain and 82% experienced improvement in their motor deficits. CONCLUSIONS: Lumbar synovial cysts are a more common cause of lumbar radicular pain than previously thought. Surgical removal of the cyst is a safe and effective treatment for symptomatic relief in patients with lumbar synovial cysts. A concomitant fusion procedure may be performed in select cases. In this study, only a few patients developed symptomatic spinal instability requiring a second operation.

Adult↗
PubMed1998

Efficacy of levodopa therapy on motor function after posteroventral pallidotomy for Parkinson's disease.

We evaluated motor function in 41 consecutive PD patients undergoing unilateral MRI/microelectrode-guided posteroventral pallidotomy to determine whether the motor effects of levodopa therapy change after surgery. Total Unified Parkinson's Disease Rating Scale motor "off" and motor "on" subscores all improved and the rapidity of action, magnitude, and duration of motor response to levodopa therapy were all maintained after pallidotomy.

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PubMed1997

Unilateral pallidotomy for Parkinson's disease: comparison of outcome in younger versus elderly patients.

We studied the effects of medial pallidotomy in the first 20 consecutive patients with Parkinson's disease (PD) undergoing this MRI/electrophysiologically guided procedure at our institution. The mean age of patients was 65.5 years (median 66.5) and none suffered any serious complications. Pallidotomy significantly improved motor function in both "on" and "off" states as measured by Unified Parkinson's Disease Rating Scale (UPDRS) motor scores and timed tests (Purdue pegboard and counter tapping) in the arm contralateral to surgery 3 months postoperatively. Patients also improved in terms of activities of daily living, reflected by improved UPDRS activity of daily living and complications of therapy scoring and reduced levodopa-induced dyskinesias; six of 11 patients who could not walk in an "off" state prior to surgery could do so postoperatively. The total UPDRS score improved by 22% from preoperative values. The aforementioned improvements occurred similarly in patients greater than (n = 11) or less than 65 years (n = 9) at surgery. Neuropsychological measures indicated that although the majority of cognitive function remains unchanged in right-handed PD patients following dominant (left) hemisphere pallidotomy, mild specific declines in word generation are present. The findings of this study suggest that unilateral pallidotomy is safe and associated with improved motor functioning in elderly as well as younger PD patients experiencing significant disability despite optimal medical therapy.

Adult↗
PubMed1996

Conservative management of acoustic neuroma: an outcome study.

OBJECTIVE: This study analyzed selection criteria, clinical outcome, and tumor growth rates in patients with acoustic neuromas in whom the initial management strategy was observation. METHODS: A retrospective review of patients with conservatively managed unilateral acoustic neuromas was conducted. Minimum follow-up was 6 months. Patients with neurofibromatosis Type II were excluded. Differences in tumor growth rates were analyzed by use of the Wilcoxon rank sum test. RESULTS: Sixty-eight patients (31 men and 37 women) with a mean age of 67.1 years were followed for an average of 3.4 years after diagnosis. The reasons for a trial of observation included advanced age (55%), patient preference (21%), minimal symptoms (9%), poor general medical condition (7%), asymptomatic tumor (4%), and tumor in the only hearing ear (4%). Fifty-eight patients (85%) were successfully managed with observation alone. Ten patients (15%) ultimately required treatment (nine received microsurgical treatment and one patient underwent radiosurgical intervention) at a mean time interval of 4.0 years after diagnosis. Forty-eight tumors (71%) showed no growth and 20 (29%) enlarged during the study period. The mean tumor growth rate at the 1-year follow-up was significantly higher in the group requiring treatment (3.0 mm) than in the group not requiring treatment (0.36 mm) (P < 0.0001). Thus, the tumor growth rate at the 1-year follow-up was a strong predictor of the eventual need for treatment. CONCLUSION: Observation is a reasonable management strategy in carefully selected patients with acoustic neuromas. Diligent follow-up with serial magnetic resonance imaging is recommended, because some tumors will enlarge to the point at which active treatment is required.

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PubMed1995

Analysis of early failures after lumbar decompressive laminectomy for spinal stenosis.

OBJECTIVE: To determine why some patients have no improvement after surgical treatment of lumbar spinal stenosis. DESIGN: We conducted a retrospective study of patients who were referred to our institution between 1990 and 1993 because their symptoms were unchanged or worsened after lumbar decompressive laminectomy. MATERIAL AND METHODS: For the 45 study patients (25 women and 20 men; mean age, 70.8 years), preoperative and postoperative clinical status, preoperative and postoperative imaging studies, and operative reports were analyzed. RESULTS: Preoperatively, only 23 patients (51%) had the clinical syndrome of neurogenic claudication, and 15 (33%) had midline low-back pain without a radicular component. Three other patients had peripheral neuropathy, and three had atypical leg pain. Only 10 patients had radiographic evidence of severe lumbar canal stenosis; the others had moderate, mild, or no stenosis. In 10 patients, surgical decompression was inadequate. Only three patients had the triad of neurogenic claudication, radiographically confirmed severe lumbar stenosis, and adequate decompression of the lumbar canal and lateral recesses. CONCLUSION: The most common pattern in patients with early failure after lumbar laminectomy was the absence of actual neurogenic claudication coupled with the absence of severe stenosis on preoperative imaging studies. The most common technical error was inadequate neural decompression. These data suggest that the outcome may be improved by more careful selection of patients and by performance of an adequate surgical decompression.

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PubMed1995

Primary lymphoma of the spinal cord.

Non-Hodgkin's lymphomas arising in the spinal cord are extremely rare. Only eight single case reports have been well confirmed in the literature. Herein we describe a 59-year-old woman with symptoms attributable to a spinal cord lesion. Physical examination revealed neurologic deficits but no evidence of tumor elsewhere. Although several imaging studies were performed, only magnetic resonance imaging with use of gadolinium revealed the exact site and extent of the lesion. Laminectomy and direct examination of the spinal cord disclosed a discolored region at the level of the 11th thoracic vertebra. A biopsy specimen was obtained, and pathologic examination revealed an intermediate grade, mixed cell lymphoma of T-cell origin. Radiotherapy was administered to the lesion and adjacent region of the spinal cord with use of 6-MV photons and an anteroposterior-posteroanterior technique; the total dose was 45 Gy in 23 fractions. No chemotherapy was given. After 3 years of follow-up, the neurologic signs and symptoms were stable, and repeated magnetic resonance imaging with use of gadolinium showed no residual tumor. In addition to the case report, we review the literature on primary lymphomas of the central nervous system and discuss treatment recommendations.

Female↗
PubMed1995

Angiocentric T-cell lymphoma presenting with multiple cranial nerve palsies and retrobulbar optic neuropathy.

Angiocentric T-cell lymphoma (lymphomatoid granulomatosis) may present with prominent central nervous system (CNS) findings with variable radiographic features. We describe a patient who presented with multiple cranial nerve palsies involving the left optic nerve, left facial nerve, left ocular motor nerves, and bilateral acoustic nerves. Enhancement of the right temporal meninges and a cavernous sinus mass were noted on magnetic resonance (MR) scan. A right temporal craniectomy and meningeal biopsy were performed. Meningeal biopsy revealed atypical angiocentric granulomatous lymphoid infiltrates without associated necrosis, giant cells, or granuloma formation. Morphologic and T-cell, receptor gene rearrangement findings were diagnostic of an angiocentric T-cell lymphoma. Retrobulbar optic neuropathy and multiple cranial nerve palsies may be the presenting features of angiocentric T-cell lymphoma. The neurologic and unique radiographic changes in our case expand the previously reported findings in CNS angiocentric T-cell lymphoma.

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