Central oscillators in a patient with neuropathic tremor: Evidence from intraoperative local field potential recordings

Abstract

Present pathophysiological concepts of neuropathic tremor assume mistimed and defective afferent input resulting in deregulation of cerebello-thalamo-cortical motor networks. Here, we provide direct evidence of central tremor processing in a 76-year-old female who underwent bilateral deep brain stimulation of the ventral intermedial nucleus of the thalamus (Vim-DBS) because of neuropathic tremor associated with IgM paraproteinemia. Electrophysiological recordings of EEG and EMG were performed in three perioperative sessions: (1) preoperatively, (2) intraoperatively, and (3) 4 days after surgery in both rest and postural tremor conditions. Tremor-related synchronization (coherence) between motor cortex (M1) and muscles (M. extensor digitorum, M. flexor digitorum) was assessed, and additional intraoperative local field potential (LFP) recordings from Vim allowed comprehensive coherence mapping in thalamo-cortico-muscular networks. Directionality of information flow was determined by directed transfer function (DTF) and phase analyses. Stimulation effects on tremor and corticomuscular coherence were assessed and the patient was followed for 12 months on clinical outcome measures (Tremor Rating Scale, CADET-Score). Vim-DBS reduced tremor (59%) and improved motor functionality in daily activities (31%, CADET-A) after 12 months. Intraoperative recordings demonstrated significant coherence in the tremor frequency (4 Hz) between M1 and contralateral muscle, Vim and ipsilateral M1, Vim and contralateral muscle, but not between Vim and contralateral M1. Information flow was directed from M1 to Vim and bidirectional between M1 and muscle and between Vim and muscle, respectively. Corticomuscular coherence at tremor frequency was completely suppressed by Vim-DBS. Our case study demonstrates central oscillators underlying neuropathic tremor and implies a strong pathophysiological rationale for Vim-DBS.

Altered corticomuscular coherence elicited by paced isotonic contractions in individuals with cerebral palsy: A case-control study

“…These results confirmed that motor brain processing was significantly altered in individuals with CP as it occurs in other movement disorders (Graziadio et al, 2012;Muthuraman et al, 2010;Weiss et al, 2012Weiss et al, , 2010Fang et al, 2009). Corticomuscular coherence is thought to reflect the functional coupling between motor cortex and muscle motor units during motor performance (Mima and Hallett, 1999).…”

“…Finally, some studies have revealed that corticomuscular coherence is affected by changes in descending drive from spinal and cortical levels. Thus, for instance, corticomuscular coherence has proven to be altered in healthy individuals after inmobilization (Lundbye- Jensen and Nielsen, 2008) or in neurological conditions such as essential (Muthuraman et al, 2010) and neuropathic tremor (Weiss et al, 2010), Parkinson disease (Weiss et al, 2012), stroke (Graziadio et al, 2012;Fang et al, 2009) or pseudo-choreoathetosis (Timmermann et al, 2001). Nevertheless, there is currently no data about the effects of cerebral palsy on corticomuscular coherence.…”

Deep brain stimulation in uncommon tremor disorders: indications, targets, and programming

“…Two studies reported no occurrence of AEs, and 2 studies did not report AEs. Stimulation frequency varied from 130 to 185 Hz, intensity from 0.6 to 4.5 V, and pulse width from 60 to 210 sec (Table 4) [12, 75–81]. …”

Postural tremor and chronic inflammatory demyelinating polyneuropathy

“…Central oscillators have also been implicated in generation of neuropathic tremor . Specifically, deep brain stimulation studies have suggested the importance of the ventral intermediate nucleus (VIM) of the thalamus, whereby stimulation of the VIM results in a significant reduction of neuropathic tremor.…”