DBS management of Tourette's Matthew Spreadbury

What is it really? “A neurological disorder characterized by involuntary tics and vocalizations and often the compulsive utterance of obscenities.” https://www.youtube.com/watch?v=KtCG0wG-5E0 A debilitating disease which often leads to self harm, reduced social interaction, reduced opportunities to work and the ability to receive a full education.

Pathophysiology? The pathophysiology of TS is still unclear. Thalamocortical drive? CM/Pf loops to the motor striatum and the substantia- periventricularis 1.Tthrough an inhibition of the indirect pathway of the basal ganglia circuit, could generate tics and compulsions 2. to the limbic striatum are implicated in TS and that it is possible that the effect of thalamic DBS is mediated through these latter circuits.

Routine medication Clonidine, guanfacine, clonazepam, haloperidol, pimozide, quetiapine, and olanzapine. High refractory rates to original symptoms. Psychiatric and behavioral therapy can be useful. Provides a community for TS sufferers.

Measurement of severity and suitability for surgery. Yale Global Tic Severity Scale 1-100 Psychiatric assessment Subjective patient assessment Patient age?? A semistructured, multidimensional test that has been developed to assess the severity of tic disorders. Fifty percent of the score is based on the tics themselves The other half reflects the level of tic-related impairment as assessed by the patient.

Surgical procedures? Ablation therapy. Target areas: Centromedian thalamus, the internal globus pallidus, the external globus pallidus, and the anterior limb of the internal capsule Thalamic CM/Pf, 5 mm lateral and 8 mm posterior to the mid-commissural point (MCP) along the superior-inferior plane of the anterior commissure-posterior commissure line. CM= Its physiological role involves attention and arousal, including control of the level of cortical activity. Internal globus pallidus =

Anatomical location Bilateral thalamic centromedian/parafascicular complex (CM/Pf)

2mm accuracy & think that there are 2000 neurons per cubic mm!

Case studies 1. A 17-year-old boy with a 12-year history of TS Jaw-clenching/teeth-grinding tics forceful enough to have caused dental fractures on several occasions. On psychiatric evaluation, his comorbid depression and obsessive-compulsive disorder (OCD) were judged to be stable, and he was approved for bilateral CM/Pf stimulation. The patient had modest early improvement in tics, and it took 6 months before optimal stimulating parameters were found. YGTSS score 6 months post operation was reduced by 60%

Case studies 2. A 35 year old woman with a 9-year history of TS and comorbid OCD and ADHD symptoms presented to our center for evaluation. Simple motor tics involving the face and arms. The tic repertoire later expanded to include complex vocalizations and patterned movements throughout all body segments. By 3 years before presentation, the patient developed forceful head tics resulting in the need for narcotic analgesia. Post op she self-rated at 99% improvement. With YGTSS score of 10!

Benefits and risks? https://www.youtube.com/watch?v=nDkrD1uCGsM Infection, haemorrhage, death. Surgical accuracy is everything! 0.4% Morbidity Paranoia, anxiety, cranial nerve palsy, elation, sadness, depression, suicidal thoughts (screening is essential). Mechanical failure, 2000 settings on the transducer (voltage, frequency etc..)

References: Leckman JF, Bloch MH, Scahill L, King RA. Tourette syndrome: the self under siege. J Child Neurol. 2006;21(8):642-649. 2. Mink JW. Basal ganglia dysfunction in Tourette’s syndrome: a new hypothesis. Pediatr Neurol. 2001;25(3):190-198. 3. Leckman JF. Tourette’s syndrome. Lancet. 2002;360(9345): 577-1586. 4. Temel Y, Visser-Vandewalle V. Surgery in Tourette syndrome. Mov Disord. 2004;19(1):3-14. 5. Visser-Vandewalle V, Temel Y, Boon P, et al. Chronic bilateral thalamic stimulation: a new therapeutic approach in intractable Tourette syndrome: report of three cases. J Neurosurg. 2003; 99(6):1094-1100. 6. Lyons MK. Deep brain stimulation: current and future clinical applications. Mayo Clin Proc. 2011;86(7):662-672. 7. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders: DSM-IV. 4th ed. Washington, DC: American Psychiatric Association; 1994:xxvii, 886.