Changes in Hand Temperature After Exposure May Aid in Early Diagnosis
Measuring changes in the temperature of the hands after immersion in cold water could be useful in making an early diagnosis of Parkinson’s disease, a small study suggests.
The study, “A Non-Invasive IR Sensor Technique to Differentiate Parkinson’s Disease from Other Neurological Disorders Using Autonomic Dysfunction as Diagnostic Criterion,” was published in Sensors late last year.
Early diagnosis of Parkinson’s is critical for a more prompt initiation of care and for better long-term outcomes. However, detecting Parkinson’s early in the disease’s course can be challenging, in part because its initial symptoms often overlap with other conditions.Tremor, for example, is a characteristic motor symptom of Parkinson’s but also found in people with the milder disorder known as essential tremor (ET).
In addition to its motor symptoms, Parkinson’s causes many non-motor complications. One of the most common is autonomic dysfunction — problems with the autonomic nervous system that controls involuntary bodily processes like heartbeat, breathing, and digestion.
Autonomic dysfunction in Parkinson’s often results in vasoconstriction, or abnormally tight blood vessels, which restricts the flow of blood especially in the extremities. Blood flow in the hands and feet is a major determinant of their temperature — and that’s where this study comes in.
A team of scientists in India devised a simple test to detect Parkinson’s-associated autonomic dysfunction related to blood flow. Simply, this involves the person being tested submerging their hands for two minutes in water that is just above freezing. After they remove their hands, a thermal camera is used to measure changes in the hands’ temperature over time.
To test this setup as a potential diagnostic tool, the researchers recruited 20 Parkinson’s patients, 20 adults with essential tremor patients, and 20 people with no known health problems. All participants were similar in terms of age, demographics, body weight, and health measures like high blood pressure or sense of smell.
By comparing hand temperatures changes, the researchers calculated patients’ recovery rates — essentially reflecting how well their hand temperature returned to normal over six minutes after cold water submersion.
The recovery rate at six minutes was significantly lower for Parkinson’s patients as compared to those with essential tremor or healthy individuals — 46.24%, as compared to 85.18% and 89.5%, respectively. Specifically, analyses showed that Parkinson’s patients had a recovery rate than was 32% less than healthy individuals and 25% less compared to essential tremor patients.
Additional statistical analyses showed that the recovery rate correlated with measures of Parkinson’s severity, such as Hoehn and Yahr staging and scores on the Unified Parkinson’s Disease Rating Scale (UPDRS). In other words, Parkinson’s patients with more severe disease tended to experience a lower recovery rate.
To assess the test’s ability to detect Parkinson’s, the researchers used a statistical metric called the area under the receiver operating curve, or AUC, which is basically a measure of how well a test can distinguish between two groups — in this case, Parkinson’s or not. AUC values can range from 0.5 to 1, with higher numbers indicating a better ability to differentiate.
The AUC for detecting Parkinson’s based on changes in hand temperature was 0.79.
The researchers concluded that measuring changes in hand temperature after submersion in cold water “proved to be effective non-invasive tests in the initial stages” of Parkinson’s disease.
“The results of this study have to be evaluated using a larger cohort of subjects so that these non-invasive tools can be used to detect PD in its early stage, which will help improve patients’ lifestyle and delay PD disease progression,” they added.