A palm-worn device to quantify rigidity in Parkinson's disease.

Background: Parkinsonian rigidity is identified on clinical examination as resistance to passive movement. Measurement of rigidity commonly relies on ordinal rating scales (MDS-UPDRS), however instrumented objective measures may provide greater mechanistic insight.

New Method: We present a palm-worn instrument to objectively quantify rigidity on a continuous scale.

Objective evaluation of bradykinesia in Parkinson's disease using an inexpensive marker-less motion tracking system.

Objective: Quantification of bradykinesia (slowness of movement) is crucial for the treatment and monitoring of Parkinson's disease. Subjective observational techniques are the de-facto 'gold standard', but such clinical rating scales suffer from poor sensitivity and inter-rater variability. Although various technologies have been developed for assessing bradykinesia in recent years, most still require considerable expertise and effort to operate.

Balance control systems in Parkinson's disease and the impact of pedunculopontine area stimulation.

Impaired balance is a major contributor to falls and diminished quality of life in Parkinson's disease, yet the pathophysiology is poorly understood. Here, we assessed if patients with Parkinson's disease and severe clinical balance impairment have deficits in the intermittent and continuous control systems proposed to maintain upright stance, and furthermore, whether such deficits are potentially reversible, with the experimental therapy of pedunculopontine nucleus deep brain stimulation. Two subject groups were assessed: (i) 13 patients with Parkinson's disease and severe clinical balance impairment, implanted with pedunculopontine nucleus deep brain stimulators; and (ii) 13 healthy control subjects.

Neurophysiological analysis of the clinical pull test.

Postural reflexes are impaired in conditions such as Parkinson's disease, leading to difficulty walking and falls. In clinical practice, postural responses are assessed using the "pull test," where an examiner tugs the prewarned standing patient backward at the shoulders and grades the response. However, validity of the pull test is debated, with issues including scaling and variability in administration and interpretation.

Clinical validation of a precision electromagnetic tremor measurement system in participants receiving deep brain stimulation for essential tremor.

Tremor is characterized commonly through subjective clinical rating scales. Accelerometer-based techniques for objective tremor measurement have been developed in the past, yet these measures are usually presented as an unintuitive dimensionless index without measurement units. Here we have developed a tool (TREMBAL) to provide quantifiable and objective measures of tremor severity using electromagnetic motion tracking.