ASSFN News & Views

Charles Mikell, MD, FAANS | August, 2020

Chronic Pain and Spasticity

  • Medtronic rolled out DTM™ (differential target multiplexed) stimulation for their Intellis system. DTM is a high-density stimulation program that depends on using multiple simultaneous stimulation frequencies to target neuroglial interactions. Despite claims of superior efficacy, and preclinical rodent data, published human data on DTM is not yet available.
  • Nevro released their Omnia generator, which has paresthesia-based settings, in addition to their signature HF10™ high-density waveform.
  • Medtronic’s Synchromed II pump was recalled in December, due to a manufacturing issue, which led to several motor stalls.

Movement Disorders

  • Nine patients who underwent DBS for Parkinson’s disease lost the ability to swim (Waldvogel, 2020). This report led to a Medtronic communique issued to all providers, to warn patients about possible loss of swimming ability.
  • Despite extensive data implicating the cerebellum in essential tremor, mechanistic information has been elusive. A group at Baylor used optogenetics to show that tremor could be turned on and off at the level of the Purkinje cells, which in turn modulate activity in deep nuclei (Brown, 2020).
  • The first long-term follow-up of voice tremor suggests that voice benefit in caudal zona incerta stimulation is sustained (Sandström, 2019). Many of the implants were unilateral, suggesting that a single electrode may be enough to treat this problem.

Epilepsy

  • A new epilepsy syndrome was described in Annals of Neurology. Four patients presented with limbic encephalitis and seizures, and careful work identified autoantibodies to drebin, an intracellular protein found in neuronal processes.
  • Epilepsy is a progressive, neurodegenerative disease. A case-control study of 190 patients with epilepsy showed that cortex progressively thins in patients with epilepsy, significantly faster than it does in normal aging (Galovic, 2019).

New Directions

  • The first case report of habenula stimulation for treatment of obsessive-compulsive disorder was published in Frontiers in Psychiatry (Zhang, 2020). The patient had a significant Yale-Brown Obsessive Compulsive Scale decrease (from 31 to 20), despite having previously failed cingulotomy and capsulotomy.
  • Eight patients with treatment-refractory schizophrenia underwent DBS with four meeting symptomatic improvement criteria, measured by PANSS (Positive and Negative Symptom Scale). One patient had an infection requiring explant, and of the remaining seven, three had nucleus accumbens electrodes and four were implanted in subgenual cingulate.
  • MR-guided focused ultrasound was used to open the blood-brain barrier in the primary motor cortex in four ALS patients (Abrahao, 2019) as well as in Alzheimer’s patients (Rezai, 2020). The treatment was well-tolerated, and opens the door for therapeutics that act directly on involved areas of the brain.

References

  1. Abrahao, Agessandro, et al. “First-in-human trial of blood–brain barrier opening in amyotrophic lateral sclerosis using MR-guided focused ultrasound.” Nature communications 10.1 (2019): 1-9.
  2. Brown, Amanda M., et al. “Purkinje cell misfiring generates high-amplitude action tremors that are corrected by cerebellar deep brain stimulation.” Elife 9 (2020): e51928.
  3. Galovic, Marian, et al. “Progressive Cortical Thinning in Patients With Focal Epilepsy.” JAMA Neurology 76.10 (2019): 1230-1239.
  4. Pitsch, Julika, et al. “Drebrin autoantibodies in patients with seizures and suspected encephalitis.” Annals of Neurology (2020).
  5. Rezai, Ali R., et al. “Noninvasive hippocampal blood− brain barrier opening in Alzheimer’s disease with focused ultrasound.” Proceedings of the National Academy of Sciences (2020).
  6. Sandström, Linda, Patric Blomstedt, and Fredrik Karlsson. “Long-term effects of unilateral deep brain stimulation on voice tremor in patients with essential tremor.” Parkinsonism & Related Disorders 60(2019): 70-75.
  7. Waldvogel, Daniel, et al. “Beware of deep water after subthalamic deep brain stimulation.” Neurology 94.1 (2020): 39-41.
  8. Zhang, Chencheng, et al. “Habenular Stimulation for Neurosurgery Resistant Obsessive-Compulsive Disorder: A Case Report.” Frontiers in Psychiatry 11 (2020): 29.