Patients with Parkinson’s disease often have persistent ocular tremors that prevent eye stability during fixation, which suggests that modern, precise oculomotor testing of this feature could serve as a biomarker for early diagnosis of Parkinson’s disease, researchers reported in the online April 9 Archives of Neurology. The investigators conducted a case-control study with 112 patients with Parkinson’s disease, 18 de novo, untreated patients, and 60 age-matched controls. Patients’ oculomotor parameters were assessed with precise eye-tracking technology, and oculomotor function between groups during fixation was compared with oculomotor function while tracking a randomly displaced target on a computer monitor. All 112 patients with Parkinson’s disease showed oscillatory fixation instability. “The pervasiveness and specificity of [ocular tremor] suggest that modern, precise oculomotor testing could provide a valuable early physiological biomarker for diagnosing Parkinson’s disease,” the study authors concluded.
Wrist-worn biosensors that continuously record the sympathetically mediated electrodermal activity (EDA) of patients with epilepsy show autonomic correlates of postictal EEG suppression that may serve as biomarkers for risk of sudden death in epilepsy, according to research published in the online April 25 Neurology. Researchers recorded a total of 34 seizures (22 complex partial; 12 tonic-clonic) in patients with refractory epilepsy who wore the wrist sensors. Analysis of the postictal period showed heightened heart rate and a surge in EDA at the same time as persistent suppression of parasympathetic-modulated high-frequency (HF) power of heart rate. In addition, increased EDA response amplitude was associated with increased duration of EEG suppression (r = 0.81), and decreased HF power was associated with increased duration of EEG suppression (r = -0.87). “The magnitude of both sympathetic activation and parasympathetic suppression increases with duration of EEG suppression after tonic-clonic seizures,” the investigators stated.
The suggested immobilization test (SIT) may assist clinicians in diagnosing restless legs syndrome (RLS) in patients with Parkinson’s disease, according to research published in the March 21 online Movement Disorders. The investigators compared SIT scores and polysomnography measures of 50 patients with Parkinson’s disease (25 with RLS), 25 patients with primary RLS, and 25 controls matched for age and sex. Results indicated that patients with Parkinson’s disease and RLS had increased mean leg discomfort scores and high leg discomfort at the end of the test compared with patients with Parkinson’s disease but without RLS. In addition, the SIT showed sensitivity of 91% and specificity of 72% for RLS diagnosis in patients with Parkinson’s disease during symptomatic time intervals. “The sensory SIT is a simple test that may help diagnose RLS in patients with Parkinson’s disease,” the researchers concluded.
—Lauren LeBano