Dual Lead Thalamic Deep Brain Recording (DBR)-DBS Interface for Closed Loop Control of Severe Essential Tremor
Dual Lead Thalamic Deep Brain Recording (DBR)-DBS Interface for Closed Loop Control of Severe Essential Tremor
This is a feasibility study based on physician-initiated Investigational Device Exemption
 (IDE) including intraoperative experiments and chronic testing of implanted dual thalamic DBS
 lead systems. This study will inform protocols for optimal use of implanted next-gen DBS
 systems for primarily tremor control in refractory essential tremor.If the approach appears
 to be successful, the pilot data generated will be used to base a future pivotal trial for
 FDA approval for enhanced tremor control and adaptive DBS (aDBS) functionality of DBS
 systems.
Ventralis intermedius nucleus of the thalamus (VIM) Deep Brain Stimulation (DBS) has emerged
 as a highly effective treatment for essential tremor, which is an incurable, degenerative
 brain disorder that results in progressively debilitating tremor, afflicting an estimated 7
 million people in the US (2.2% of the population). Clinical observation shows, however, that
 disease progression results in eventual recurrence of debilitating tremor in 10 to 20% of VIM
 DBS patients. DBS revision surgery, with replacement of sub-optimally positioned VIM DBS
 leads and addition of an ipsilateral ventralis oralis (VO) DBS lead, has emerged as an
 effective rescue strategy for many such patients with delayed failure of VIM DBS therapy.

 Since essential tremors are typically not continuous, tremor suppressing DBS therapy need not
 necessarily be delivered continuously and could theoretically be effective if delivered only
 when movement intent or tremor is present.

 Our central hypothesis is that a VIM+VO DBS system capable of detecting the neurophysiologic
 markers of essential tremor (ET) associated with goal directed movements, and providing
 responsive dual lead thalamic stimulation in a targeted and personalized manner, would
 provide improved suppression of severe tremor, reduce adverse effects associated with
 continuous stimulation, and prolong the battery life of the implantable neurostimulator
 (INS), decreasing the frequency of surgical procedures necessary to replace devices with
 depleted batteries.
Inclusion Criteria:

 -  Patient gives an informed consent.

 -  Patient is over 21 years of age.

 -  Patient is diagnosed with a postural-intention (essential) tremor for at least 3
 years, meets diagnostic criteria for ET, has been evaluated and examined by a movement
 disorders fellowship trained neurologist, and is being treated with traditional VIM
 DBS therapy.

 -  Patient has no evidence of non-ET central nervous system disease or injury and has had
 a significantly disabling, upper extremity tremor despite ongoing VIM DBS therapy for
 at least three (3) months prior to DBS revision surgery.

 -  Patient has a postural or kinetic tremor severity score of at least 2 out of 4 in the
 extremity intended for treatment on the Fahn-Tolosa-Marin Clinical Rating Scale for
 Tremor (TRS) despite ongoing VIM DBS therapy.

 -  Patient has a TRS score of 2 or above in any one of the items 16-23 from the
 Disability subsection of the TRS: speaking, feeding other than liquids, bringing
 liquids to mouth, hygiene, dressing, writing, working and social activities despite
 ongoing VIM DBS therapy.

 -  Patient's tremor is refractory to adequate trials of at least two medications, one of
 which should be either propranolol or primidone. Proof of this is not required for
 patients with a current device that is being removed and replaced with a new device.
 An adequate medication trial is defined as a therapeutic dose of each medication or
 the development of side effects as the medication dose is titrated.

 -  Patient is available for appropriate follow-up times for the length of the study.

 Exclusion Criteria:

 -  Any previous neurosurgical intervention other than VIM DBS, including ablative brain
 lesions for tremor suppression.

 -  Medication related movement disorders.

 -  Any suspicion of Parkinson's disease, including presence of Parkinsonian features such
 as bradykinesia, rigidity, or postural instability.

 -  Any behaviors consistent with alcohol or substance abuse as defined by the criteria
 outlined in Diagnostic and Statistical Manual of Mental Disorders (DSM-V).

 -  Severe medical co-morbidity including cardiovascular disorder, lung disorder, kidney
 disease, continuous neurological disease, hematological disease, or frailty that
 impact tolerability of the surgery as judged by the screening physicians.

 -  Abnormal brain MRI including hydrocephalus, stroke, structural lesions, demyelinating
 lesions, or infectious lesions. Also excluded will be subjects with severe brain
 atrophy.

 -  Any uncontrolled symptoms or signs of increased intracranial pressure (e.g., headache,
 nausea, vomiting, lethargy, papilledema).

 -  A history of seizures within the past year.

 -  A dementia rating scale score (DRS) <130 signifying significant cognitive dysfunction
 and a potential for inability to cooperate with tasks involved in the study.

 -  Any attempt or intent of suicide during the previous six months.

 -  Presence or history of psychosis.

 -  Any person known to have abnormal coagulation or any medications which interfere with
 coagulation

 -  Significant untreated or unstable mood disorders including depression. This will be
 determined by the Neuropsychological team during FastTrack and by the Neurologist

 -  In addition, patients who are pregnant or plan to become pregnant will be excluded
 from this study.