Evaluation of Quantitative Measurement Techniques for Head Tremor With Thalamic Deep Brain Stimulation.

BACKGROUND: Ventralis intermedius thalamic deep brain stimulation (VIM DBS) has shown to be safe and effective for medically refractory essential tremor (ET). We evaluate the use of quantitative tremor measurement methods for head tremor in ET using a "smart" hat and a smartphone application. METHODS: We enrolled 13 ET patients who previously underwent VIM DBS. Head and arm tremor was measured ON and OFF stimulation using the clinical gold standard Fahn-Tolosa-Marin Tremor Rating Scale (TRS). Results were then compared to two quantitative measurement techniques: Lift Pulse (smartphone application) and modified Nizet (adapted laser point measurement from Nizet et al.). Spearman's rank correlation was used to compare tremor severity and improvement on stimulation using TRS and quantitative methods to measure tremor. RESULTS: Lift Pulse tremor severity measurement significantly correlated with TRS for head (ρ = 0.53, p < 0.01) and arm tremor (ρ = 0.49, p < 0.01). Modified Nizet tremor severity measurement significantly correlated with TRS for head (ρ = 0.83, p < 0.001) and arm tremor (ρ = 0.50, p < 0.01). Inter-method correlation for head tremor severity was significant (ρ = 0.45, p < 0.05). Lift Pulse tremor improvement measurement significantly correlated with TRS for arm tremor (ρ = 0.56, p < 0.05). Modified Nizet tremor improvement measurement significantly correlated with TRS for head tremor (ρ = 0.53, p < 0.01). DISCUSSION: Our results show that Lift Pulse and modified Nizet are both effective techniques to quantitatively measure head and arm tremor severity. We also show the utility of a "smart" hat to measure head tremor. Modified Nizet technique is more effective for measuring head tremor, while Lift Pulse is an effective measure of tremor severity, especially arm tremor improvement.

BMI as a Predictor of Spinal Cord Stimulation Success in Chronic Pain Patients.

BACKGROUND: Spinal cord stimulation (SCS) is an effective method of treating chronic pain. Obese patients are overrepresented in chronic pain cases. We examine the effect of body mass index (BMI) on SCS success. METHODS: We prospectively follow outcome measures including visual analog score, Beck Depression Inventory (BDI), McGill Pain Questionnaire, Oswestry Disability Index (ODI), Pain Catastrophizing Scale (PCS), and the Insomnia Severity Index at baseline, six months, and one year postoperatively. Retrospectively, we examined whether our patients with a BMI above the 75th percentile (BMI ≥36.5) had worse outcomes. RESULTS: Our analysis included thoracic and cervical SCS patients-19 with a BMI ≥36.5 and 58 with a BMI <36.5. High BMI patients experienced less BDI improvement at 6 months (T(df) 2.257(36); p = 0.030; 95% CI [4.7%, 87.4%]) and one year (2.74(28); p = 0.011; 95% CI [18.1%, 125.0%]) post-SCS. High BMI patients had less improvement in pain as measured by the PCS at one year (U = 79.5; p = 0.045; 95% CI [-116.0%, 0.0%]). DISCUSSION: Each group experienced successful surgical outcomes. High BMI patients had less BDI improvement at six months and one year and less PCS improvement at one year. These data aid us in counseling our patients preoperatively.

The Impact of Spinal Cord Stimulation on Sleep Patterns.

BACKGROUND: Studies of chronic pain show sleep disturbances to be a prevalent symptom in 50-88% of patients and studies show improved pain to correspond with improved sleep. The impact of spinal cord stimulation (SCS) on sleep in failed back surgery syndrome, complex regional pain syndrome, and neuropathic pain patients has not been studied prospectively. OBJECTIVES: We prospectively assess the impact of SCS on sleep quality using the Insomnia Severity Index (ISI) and Epworth Sleepiness Scale (ESS). Further we examine the correlations between sleep and pain. METHODS: Patients who underwent permanent SCS implantation completed six validated questionnaires to compare sleep patterns, pain intensity, and quality of life at baseline and six months postoperatively. Results were analyzed via paired samples t-tests and bivariate analysis. RESULTS: Data from 27 patients were collected. We saw a significant decrease in ISI scores (n = 23, t(df)=2.9(22), p = 0.008), and noted a trend in the percentage improvement between ISI and ESS (n = 12, t(df)=2.0(10), p = 0.078). We did not see any significant improvement in ESS. However, improvements in insomnia correlated with pain intensity as measured through visual analog scale score and McGill Pain Questionnaire (R = 0.546, p = 0.007 and R = 0.559, p = 0.006, respectively). DISCUSSION: We demonstrate that insomnia scores on ISI improve with SCS at six-month follow-up. Further, we find that improvements in pain correlate with these ISI improvements.

The Impact of Peripheral Nerve Stimulation on Disability and Depression.

BACKGROUND: Peripheral nerve stimulation (PNS) of the named nerves of the head has been shown to be effective in reducing pain levels in patients with chronic pain refractory to other treatments. However, the impact of cranial PNS on depression and disability has not been well documented. OBJECTIVES: We prospectively examine the impact of PNS on quality of life via validated survey scores which assess symptoms of depression and daily functional capacities within patients. METHODS: Patients who underwent permanent PNS implantation completed five validated questionnaires: Oswestry Disability Index (ODI), the Beck's Depression Inventory (BDI), the Pain Catastrophizing Scale (PCS), McGill Pain Questionnaire (MPQ), and the visual analog scale (VAS) score. These were completed at baseline, six months, and one year to assess changes in functioning levels. Results were analyzed via repeated measures ANOVA and bivariate analysis. RESULTS: Compared with baseline, at six months patients showed significantly less depression on BDI (F = 7.9, p = 0.021), and at one year, a significant decrease in disability was observed on the ODI (F = 6.1, p = 0.036). At both six months and one year, patients showed a significant decrease in pain on VAS (F = 16.5, p = 0.012). We noted a trend for ODI to correlate with BDI at six months (R = 0.616, p = 0.077). DISCUSSION: Our prospective data show PNS to be an effective modality in improving overall life quality by limiting depression and disability as well as pain.

The Influence of Bilateral Subthalamic Nucleus Deep Brain Stimulation on Impulsivity and Prepulse Inhibition in Parkinson's Disease Patients.

BACKGROUND: At least 14% of Parkinson disease (PD) patients develop impulse control disorders (ICDs). The pathophysiology behind these behaviors and the impact of deep brain stimulation in a real-life setting remain unclear. OBJECTIVES: We prospectively examined the impact of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on ICDs in PD patients, as well as the relationship between impaired sensorimotor gaiting and impulsivity. METHODS: Patients undergoing bilateral STN-DBS were assessed for ICDs preoperatively and 1-year postoperatively using a validated questionnaire (QUIP-RS). A subset of patients completed the Balloon Analogue Risk Task (BART) and auditory prepulse inhibition (PPI) testing. RESULTS: Analysis revealed 12 patients had an improvement in score assessing ICDs ('good responders'; p = 0.006) while 4 had a worse or stable score ('poor responders'; p > 0.05). Good responders further exemplified a significant decrease in hypersexual behavior (p = 0.005) and binge eating (p = 0.01). Impaired PPI responses also significantly correlated with impulsivity in BART (r = -0.72, p = 0.044). DISCUSSION: Following bilateral STN-DBS, 75% of our cohort had a reduction in ICDs, thus suggesting deep brain stimulation effectively manages ICDs in PD. The role of impaired PPI in predisposition to ICDs in PD warrants further investigation.