Combination targeting of subthalamic nucleus and ventral intermediate thalamic nucleus with a single trajectory in deep brain stimulation for tremor-dominant Parkinson's disease.

Deep brain stimulation (DBS) has traditionally been used to target the subthalamic nucleus (STN) or globus pallidus internus (GPi) to treat Parkinson's disease (PD) and the ventral intermediate thalamic nucleus (VIM) to treat essential tremor (ET). Recent case reports have described targeting both the STN and VIM with a single trajectory and electrode to treat patients with tremor-dominant PD, yet outcome data for this procedure remains sparse. Our objective is to determine the safety and efficacy of combination STN-VIM DBS. We conducted a single-center retrospective case series of all patients who underwent combined STN-VIM DBS. Demographic, perioperative, and outcome data, including Unified Parkinson Disease Rating Scale-III (UPDRS) and tremor scores (OFF-medication), and levodopa equivalent daily dose (LEDD), were collected and analyzed. Nineteen patients underwent this procedure. Patients were 89% male and 11% female, with a mean age of 63.6 years. Mean preoperative UPDRS was 24.1, and LEDD was 811.8. At a mean follow-up of 33.8 months, UPDRS and LEDD decreased by an average of 9.2 (38.2%) and 326.3 (40.2%), respectively. Tremor scores decreased by 4.9 (59.0%), and 58% were able to decrease total medication burden. One patient developed transient left-sided weakness, yielding a complication rate of 5.3%. Combined targeting of STN and VIM thalamus via a single frontal trajectory for tremor-dominant Parkinson's Disease results in similar UPDRS outcomes to STN DBS and improved control of tremor symptoms. Larger multicenter studies are necessary to validate this as the optimal DBS target for tremor-dominant PD.

Implicit sequence learning in people with Parkinson's disease.

Implicit sequence learning involves learning about dependencies in sequences of events without intent to learn or awareness of what has been learned. Sequence learning is related to striatal dopamine levels, striatal activation, and integrity of white matter connections. People with Parkinson's disease (PD) have degeneration of dopamine-producing neurons, leading to dopamine deficiency and therefore striatal deficits, and they have difficulties with sequencing, including complex language comprehension and postural stability. Most research on implicit sequence learning in PD has used motor-based tasks. However, because PD presents with motor deficits, it is difficult to assess whether learning itself is impaired in these tasks. The present study used an implicit sequence learning task with a reduced motor component, the Triplets Learning Task (TLT). People with PD and age- and education-matched healthy older adults completed three sessions (each consisting of 10 blocks of 50 trials) of the TLT. Results revealed that the PD group was able to learn the sequence, however, when learning was examined using a Half Blocks analysis (Nemeth et al., 2013), which compared learning in the 1st 25/50 trials of all blocks to that in the 2nd 25/50 trials, the PD group showed significantly less learning than Controls in the 2nd Half Blocks, but not in the 1st. Nemeth et al. (2013) hypothesized that the 1st Half Blocks involve recall and reactivation of the sequence learned, thus reflecting hippocampal-dependent learning, while the 2nd Half Blocks involve proceduralized behavior of learned sequences, reflecting striatal-based learning. The present results suggest that the PD group had intact hippocampal-dependent implicit sequence learning, but impaired striatal-dependent learning. Thus, sequencing deficits in PD are likely due to striatal impairments, but other brain systems, such as the hippocampus, may be able to partially compensate for striatal decline to improve performance.

Geste antagonistes in idiopathic lower cranial dystonia.

Geste antagonistes, or sensory tricks, are well described in focal dystonia affecting the neck, hand, and face. Improvement in dystonic movements is typically maintained while the trick is performed, but disappears when the geste ends. We investigated the phenomenological features of geste antagoniste maneuvers in 19 patients with idiopathic lower cranial dystonia who were prospectively evaluated over a period of 6 years. Of the 19, 10 were men, mean age of onset was 49.8 years, and the most commonly involved lower cranial area was the jaw (10 patients). In most patients, dystonia was task-specific. Taking advantage of the improvement with a sensory geste, we manufactured oral appliances that mimicked the geste in 8 patients, and 3 continue to use it.

Is focal task-specific dystonia limited to the hand and face?

Focal task-specific dystonia (FTSD) of the hand and face have been well described; however, FTSD of the leg is exceedingly rare. We describe and demonstrate by videotape 2 patients with FTSD affecting the leg, in both cases triggered specifically by walking down steps. Walking on a level surface, up steps, and down steps backward, and sideways were normal. An interoceptive sensory trick (imagining walking in a different modality) led to temporary improvement. Our patients appear to demonstrated that task-specificity in focal dystonia may not be limited to skilled, rehearsed actions and that FTSD may occur in an activity that is relatively autonomic.

Common misdiagnosis of a common neurological disorder: how are we misdiagnosing essential tremor?

BACKGROUND: As a common neurological disorder, the diagnosis of essential tremor (ET) is considered routine. Despite this, previous work suggests that misdiagnoses may be common. Among other things, these misdiagnoses can lead to treatment errors. OBJECTIVES: To estimate how often other tremor disorders are misdiagnosed as ET and to identify factors that increase the odds of misdiagnosing ET and to precisely quantify the extent to which they do so. DESIGN: Seventy-one consecutive patients underwent an evaluation at the Neurological Institute of New York, New York, between January 1, 2000, and December 31, 2005; these patients had a pre-evaluation diagnosis of ET. The criteria for ET were adapted from the consensus statement of the Movement Disorder Society. RESULTS: Twenty-six patients (37%) were misdiagnosed as having ET ("false ET"). Their true diagnoses were Parkinson disease (11 patients [15%]), dystonia (6 patients [8%]), Parkinson disease with ET (5 patients [7%]), and other disorders (4 patients [6%]). Factors associated with misdiagnosed ET included unilateral arm tremor (odds ratio, 10.5; 95% confidence interval, 1.2-95.4; P=.02), spooning of the hands and other dystonic postures (odds ratio, 16.3; 95% confidence interval, 4.0-66.4; P<.001), and other unusual features (isolated thumb tremor, isolated leg tremor, and non-rhythmic tremor) (odds ratio, 49.4; 95% confidence interval, 2.7-895.0; P<.001). CONCLUSIONS: About 1 in 3 patients with tremor was misdiagnosed as having ET, with the most frequent false diagnoses being Parkinson disease and dystonia. Several factors that increased the odds of misdiagnosing ET were identified. These factors could be incorporated into improved diagnostic algorithms.

Identification and treatment of cervical and oromandibular dystonia in acutely brain-injured patients.

INTRODUCTION: Primary cervical and oromandibular dystonia (CD and OMD, respectively) are well-recognized movement disorders, often treated with botulinum toxin (BTx). In contrast, dystonia related to acute brain injuries is not well delineated. Our objective was to define in neurocritically ill patients the clinical characteristics of CD and OMD and to investigate the safety of BTx. METHODS: All acutely brain-injured patients admitted to a neurocritical care unit over a 10-month period were prospectively screened for CD and OMD. Clinical characteristics, etiology of brain injury, and pattern of dystonia were analyzed. Patients with clinically significant CD and OMD were treated with BTx and followed for 12 weeks. RESULTS: Of 165 patients screened, 33 had new-onset CD or OMD. Of 21 patients enrolled, 14 had CD, 5 had OMD, and 2 had both. The pattern of brain injury included 13 cerebral hemorrhages, 6 ischemic strokes, 1 status epilepticus, and 1 unclear etiology. Improvement after BTx was seen in four of seven patients with CD and two of four with OMD; no adverse effects occurred. Spontaneous improvement was recorded in 7 of 11 nontreated patients with CD or OMD. CONCLUSIONS: Acute secondary CD or OMD, associated with a variety of causes, was identified in 20% of acutely brain-injured patients. The temporal profile of dystonia onset and resolution in these patients was variable. Treatment with BTx in the neurocritical care setting seems to be safe. Future, larger scale randomized studies should evaluate the effectiveness of BTx treatment in this patient population.