Biomedical subjects

R Frysinger

Publications and source records attributed to R Frysinger.

4 recordsLinked to original sources

PubMed2001

Staged bilateral pallidotomy for treatment of Parkinson disease.

OBJECT: Several investigators have described the motor benefits derived from performing unilateral stereotactic pallidotomy for the treatment of Parkinson disease (PD), but little is known about the efficacy and complication rates of bilateral procedures. The goal of this study was to assess both these factors in 12 patients. METHODS: Eleven patients with medically intractable PD underwent staged bilateral pallidotomy and one patient underwent a simultaneous bilateral procedure. Unilateral pallidotomy resulted in an improvement in the patients' Unified Parkinson Disease Rating Scale (UPDRS) total scores and motor subscores, Hoehn and Yahr stages, and Schwab and England Activities of Daily Living scores. There were no complications. The second procedures were performed 5 to 25 months after the first, and nearly complete 3-month follow-up data are available for eight of these patients. Staged bilateral pallidotomy did result in further improvements in some symptoms, but the patients proved to be less responsive to levodopa. In contrast to outcomes of the initial unilateral pallidotomy, there were significant complications. One patient suffered an acute stroke, two patients suffered delayed infarctions of the internal capsule, four patients had mild-to-moderate worsening of speech and increased drooling, and one patient complained of worsening memory. CONCLUSIONS: Bilateral pallidotomy results in modest benefits but is associated with an increased risk of complications.

Adult↗

PubMed1999

Correlation between MRI-based stereotactic thalamic deep brain stimulation electrode placement, macroelectrode stimulation and clinical response to tremor control.

In this study we compared the position of the electronically active contact of the thalamic (Vim) deep brain stimulation (DBS) electrode to the stereotactic location of its tip. Fifteen patients with either Parkinson's disease (PD) or essential tremor (ET) underwent stereotactic, MRI-based placement of the Medtronic quadripolar DBS electrode. An overall improvement of 69% was achieved in the tremor scores during a period of 1-13 months after implantation of the DBS electrode. Eleven patients with ET showed 70% clinical improvement of tremor, compared to a 58% response observed in the 4 patients with PD. The electrode tip center was 11.2 +/- 1.54 mm lateral to the third ventricular wall, 5.38 +/- 1.02 mm anterior to the posterior commissure and 2.9 +/- 3.57 mm inferior to the level of AC-PC line. The most significant deviation from the planned stereotactic target was observed in the Z-coordinate. In our group of patients, stimulation settings favored the contacts closer to the AC-PC line, correcting the electrode tip position to 0.80 +/- 2.84 mm (p < 0.001) inferior to the level of the AC-PC line. In our experience, thalamic DBS offers a reversible and adjustable 'lesion' to compensate for the anatomic variabilities encountered in the positioning of the DBS electrode tip.

Aged↗

PubMed1998

Motor, cognitive, and behavioral performance following unilateral ventroposterior pallidotomy for Parkinson disease.

OBJECTIVE: To evaluate the effects of ventroposterior pallidotomy on motor disability and on behavior and cognition in patients with medically intractable idiopathic Parkinson disease. DESIGN: Detailed motor testing both while receiving and discontinuing levodopa medication, posturography, and neurocognitive and behavioral assessments were performed before and 3 to 6 months after unilateral ventroposterior pallidotomy. SETTING: University-based movement disorder program. PATIENTS: Thirty-two patients without dementia with medically refractory idiopathic Parkinson disease were studied. MAIN OUTCOME MEASURES: Motor function and disability were measured using the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, and the Schwab and England Activities of Daily Living Scale. Dynamic balance was measured by sway (amplitude and velocity) using the Chattecx Balance System. Detailed cognitive and behavioral assessments were also performed both before and after surgery. RESULTS: Eighty-three percent of patients experienced improvement of their total Unified Parkinson's Disease Rating Scale score at 3 to 6 months after surgery. Significant improvements were also seen in the contralateral Unified Parkinson's Disease Rating Scale motor subscore (78%) as well as in the contralateral Unified Parkinson's Disease Rating Scale total score both during the on and off period (78% and 79%, respectively). The Hoehn and Yahr stage, Schwab and England Activities of Daily Living Scale score, and dynamic balance when standing on foam also improved following unilateral pallidotomy in many patients. Cognitive performance remained relatively unchanged following surgery with the exception of category fluency, which exhibited a modest decline (P < .04). A significant improvement in depression was found on the Beck Depression Inventory. CONCLUSIONS: Ventroposterior pallidotomy significantly improves motor performance and daily level of function in Parkinson disease. Cognition and behavior are not adversely affected in patients without dementia, and a cognitive screening battery is proposed.

Adult↗

PubMed1983

Human factors in the measurement of the masseteric silent period.

Human variability in the measurement of the masseteric silent period (SP) was quantified. There were significant differences among (1) observer groups (technicians and dental students), (2) individual observers, (3) repeated measures of the same SP, and (4) trials. No significant observer bias was found. SP's were significantly longer at an inter-incisal distance of 10 mm (48.8 +/- 5.4 ms) than at 14 or 19 mm (44.7 +/- 9.8 ms, 44.5 +/- 6.5 ms).

Adult↗