Long-term follow-up of thalamic deep brain stimulation for essential tremor – patient satisfaction and mortality

Background Ventral intermediate thalamic nucleus (VIM) deep brain stimulation (DBS) is an effective treatment for tremor, but there is limited data on long-term efficacy and mortality after VIM-DBS. Here we report the analysis of patient satisfaction and mortality in all patients treated in our center 1996–2010 with VIM-DBS for essential tremor (ET). Methods Forty-six consecutive patients were included in this study. Medical records were reviewed, and a follow-up questionnaire was sent to all surviving patients. Results Seventy percent of all possible participants (26 patients) answered the questionnaire. Follow-up time for the responding patients was median 6.0 years (2–16). Median self-reported score on visual analogue scale of the initial postoperative effect on tremor was 8.5 (0.1–10), with a significant reduction to 7.4 (0–10) at follow-up (p = 0.001). Patients reported a median score of 10 (0–10) for overall patient satisfaction with VIM-DBS treatment. Eight patients (17%) died after median 8.9 years (0.6–15) after surgery, at median age 77.4 years (70–89). One patient (2%) committed suicide seven months after the operation. Calculated standard mortality ratio among ET patients was 1.3 (CI 0.6–2.6), similar to the general population. Conclusion We found no significant increase in mortality in this cohort of VIM-DBS operated ET patients compared to the general population in Norway. The patients reported high long-term satisfaction and continuing effect of VIM-DBS on tremor even after many years. VIM-DBS therefore seems to be an effective symptomatic long-term treatment of ET. However, one patient committed suicide. Only one other suicide has previously been reported after VIM-DBS. It is therefore still unclear whether VIM-DBS increases suicide risk

Data on all the cases of infection.

<p>(M = male, F = female, PD = Parkinson’s disease, Dy = dystonia (primary), ET = essential tremor, PKAN = pantothenate kinase-associated neurodegeneration, STN = nucleus subthalamicus, ViM = ventral intermediate nucleus of thalamus, GPi = internal globus pallidus, IPG = Implanted Pulse Generator, replacem = replacement, reimpl = reimplantation, postaur = postauricular, R = right, L = left, S. aureus = Staphylococcus aureus, CoNS = coagulase-negative Staphylococci (includes S. epidermidis and S. capitis), NA = not applicable (test not obtained), B = bilateral).</p

Number of infections in relation to possible risk factors.

<p>(M = male, F = female).</p><p>*21 with unknown smoking status.</p

Infection treatment flowchart.

<p>Infection treatment flowchart.</p

Examples on the different types of infection.

<p>A) Superficial incisional SSI. B) Deep incisional SSI. C) Organ/space SSI. (SSI = surgical site infection).</p

Number of days until onset of infection compared with culture results.

<p>S. aureus infections have earlier onset than in the CoNS group (p-value 0.02, Mann-Whitney U Test). (S. Aureus = Stahylococcus Aureus, CoNS = coagulase negative staphylococci).</p