deep brain stimulation

Deep brain stimulation is used in a variety of clinical settings, predominantly in patients with poorly controlled movement disorders. Although effective, its exact mode of function continues to be poorly understood .

Careful patient selection and target selection are essential if the procedure is to have good efficacy.

Indications

  • Parkinson disease
  • severe essential tremor
    • ventral intermediate nucleus
  • dystonia (cervical dystonia and tardive dystonia)
    • globus pallidus (pars interna)
  • cluster headaches
  • chronic pain
  • neuropsychiatric disorders: largely experimental
    • Tourette syndrome
      • centromedian parafascicular complex (thalamus)
    • medically refractive depression
      • white-matter tracts adjacent to cingulate gyrus
      • nucleus accumbens
    • obsessive-compulsive disorder
      • anterior limb of internal capsule
      • subthalamic nucleus
      • striatum

Procedure

A stereotactic frame is applied and imaging obtained to enable accurate target selection. With the aid of multiplanar reformats and operative stereotaxis, a burr hole is made for each probe and the electrode passed to the desired target, avoiding the lateral ventricles, vessels and sulci. Intraoperative stimulation is then performed to ensure adequate positioning. Leads are tunnelled under the skin and the internal pulse generator implanted in a similar location to a pacemaker.

Complications

Complications can be immediate or delayed :

  • immediate
    • hemorrhage (~1.5%)
    • infarction
    • local brain parenchymal edema (~3%)
      • unilateral or bilateral
      • 4-120 days postoperatively
      • asymptomatic or present with headache, seizure
  • delayed
    • infection (~12.5%): most commonly the pulse generator pocket
    • lead fracture (~10%)

Side effects predominantly relate to the stimulation itself, which may lead to dysarthria, disequilibrium, motor disturbances and paresthesia. These symptoms vary with the location of the probes.