In this study the investigators aim to enroll patients scheduled to undergo deep brain stimulation (DBS) implantation for movement disorders for intra-operative testing. In addition to standard-of-care surgical procedure to implant deep brain stimulation electrode leads, participants will also be stimulated and recorded from cortical areas by a temporary strip electrode (1X6) in the subdural space. The electrodes will be connected to external stimulators and a series of experiments will be performed to assess effects of the DBS on movement quality and electrophysiology measures. Results of this study will elucidate the biological mechanisms related to deep brain stimulation in modulating motor and speech function in patients with abnormal movement disorders.
Essential tremor patients who are scheduled to undergo deep brain stimulation surgery at UPMC Presbyterian with asymmetric essential tremor symptoms will be included, with the tested limb corresponding to the least affected arm to better approximate normal function. These patients are implanted bilaterally regardless of symptom laterality, as the natural history of essential tremor indicates eventual bilateral symptoms.
Parkinson's Disease patients who are scheduled to undergo deep brain stimulation surgery at UPMC Presbyterian with a history of Parkinson's Disease will also be recruited for intra-operative stimulation of their STN-targeted implants, to assess if VIM/VOP has high specificity for improving motor output.
Patients will be excluded from the study if there is any seizure history, to avoid the increased epileptogenic risk of intraoperative stimulation.
Patients with significant bilateral tremor that precludes completion of motor tasks.
Single group
Direct cortical stimulation and deep brain stimulation of motor thalamus
DeviceAll participants enrolled will undergo implantation of deep brain stimulation electrode leads for treatment of movement disorders. In addition to standard-of-care subcortical mapping using micro-electrode recording (MER) and macrostimulation mapping during DBS placement, cortical local field potentials (LFPs) will be simultaneously recorded from primary motor (M1) and somatosensory (S1) cortical areas by placement of a temporary strip electrode (1X6) in the subdural space. The strip electrode over M1 will be used to produce motor evoked potentials to contralateral hand muscles from direct cortical stimulation (DCMEPs). Cortical and subcortical LFPs will be obtained alongside electromyographic (EMG) data while the patient performs contralateral upper extremity movement tasks and a variety of articulation exercises.
Electromyography Activity
The investigators will record electromyography activity (EMG) to measure the motor evoked potentials of upper limb and facial muscles. At the end of the procedures these needles and/or the superficial adhesive electrodes will be removed. Based on the preliminary data, the investigators will consider the number of participants with at least an 18% increase in muscle activation as minimally acceptable.
Facial Muscle Motor Function - Muscle Strength
The investigators will use electromyography (EMG) testing to measure muscle strength produced by the subject during isometric facial movements (e.g. smile, tongue out, puckered lips, and open-close mouth). Amplitude of movement will be calculated by Area-Under-the-Curve with units of uV\^2/ms. Based on the preliminary data, the investigators will consider the number of participants with an increase of 50% in ROM as a minimally acceptable improvement in muscle strength.
Facial Muscle Motor Function - Range of Motion
The investigators will use electromyography (EMG) testing to measure range of motion produced by the subject during isometric facial movements (e.g. smile, tongue out, puckered lips, and open-close mouth). Based on the preliminary data, the investigators will consider the number of participants with an increase of 50% in ROM as a minimally acceptable improvement.
Speech Intelligibility
The investigators will use the Assessment of Intelligibility of Dysarthric Speech (AIDS) to assess the quality of communication and intelligibility of speech at both word- and sentence-level. Intelligibility is calculated as the percentage of words correctly identified in the single-word task, and as the percentage of correctly transcribed words and speech rate (in words per minute) in the sentence task. Based on the preliminary data, the investigators will consider the number of participants with an improvement of 5% correctly transcribed to be minimally acceptable.
Dexterity of Articulation AMRs
The investigators will measure dexterity of articulation by alternating motion rates (AMRs) of the repetitive plosive sound (pah, tah, and kah). Based on the preliminary data, the investigators will consider the number of participants with an improvement of 10% in the rate to be minimally acceptable.
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Jorge Gonzalez-Martinez
Lead sponsor
University of Pittsburgh
Sponsor institution
