After Parkinson’s led to his grandfather’s fall, he built a wearable to help patients walk and prevent leg-freeze

Research in neuromuscular physiology shows that walking is not governed solely by conscious brain control but also by spinal circuits and patterned sensory feedback. When these internal cues fail — as in Parkinson’s disease — external rhythmic cues can help restore movement continuity. Desai focussed on the Freezing of Gait (FOG) disabling symptom. “This is a sudden, temporary inability to take steps, feeling like your feet are glued to the floor when you start to walk. As the torso and other limbs move forward because of the body’s momentum, the patient falls. So, we developed a wearable device, which uses muscle stimulation to improve coordination while walking,” says Desai.

Worn as a band on the legs, WALK, as the device is called, collects data and tracks symptoms that may lead to falls. When it detects limb freezing, the device provides rhythmic vibrations or mild electrical stimuli to the leg muscles. These sensory cues “reset” the spinal cord’s control, helping in uninterrupted movement.

Based on initial results, this wearable device helped in reducing gait issues by roughly 50 per cent. It was further tested at NIMHANS (National Institute of Mental Health and Neurosciences), Bengaluru. Dr Pramod Kumar Pal, professor and programme director of the post-doctoral fellowship programme in movement disorders, says WALK significantly reduced the number, severity and duration of freezing episodes.

How does the wearable work?

Sensors on the device continuously analyse walking patterns in real-time. When gait irregularities like hesitation or rhythm changes are detected, the system gets triggered. Then it sends patterned, gentle vibrations and mild electrical pulses to the thigh muscles. “This stimulation targets the spinal cord, helping it bypass the faulty communication from the brain caused by Parkinson’s,” says Desai.

A mobile app allows users to customise settings, track progress and do specific exercises. Doctors can remotely monitor walking data and adjust therapy. “Drugs are only partially effective and each such event prevented is a fall potentially prevented,” says Desai, who obtained regulatory approvals in July 2024. “We have now introduced features that allow individuals to measure their risk of fall at home and give personalised physical therapy on the basis of these assessments,” he adds.

How the device fared in NIMHANS studies

“We began with an initial sample size of 20 and need to undertake bigger studies with larger sample size,” Dr Pal says. While there are technological tools that are used to track movement, tremor, gait, voice and dexterity outside the clinic like smart watches, multiple sensors worn on limbs (wrists/ankles), torso and others, Dr Pal says these are costly, subject to availability and need movement disorders specialists to interpret data. “These are also not commonly used in India,” he says. This device is multifunctional but needs to become affordable with scalability. “But it is a more accessible alternative to complex, invasive, or much higher-priced neuro-stimulation treatments,” says Desai.

Why patients need more wearables for leg-freezes

FOG is one of the most debilitating motor symptoms observed in patients in advanced stages. “It is usually observed in up to 50 per cent of patients and its prevalence increases to over 60 per cent in advanced stages,” Dr Pal says. “FOG is brief, usually lasts for a few seconds, but may go up to 30 seconds. It is an episodic inability to lift up feet while walking or turning,” he adds.

Common triggers for a FOG episode are walking, turning, navigating through narrow spaces like doorways or crowded places, anticipatory anxiety and dual tasking.

How to prevent freezing episodes?

Sensory cueing in the form of visual stimulus on the floor in front (such as a laser beam or some objects), tactile stimulus on feet and auditory stimulus can improve FOG in many patients, according to Dr Pal. Often patients with FOG can negotiate up and down stairs better than walking on flat ground, as the steps act like visual cues.

“The patient is the main person who can sense freezing and probably falls as a consequence. Sensors in wearable shoes can identify pressure changes in muscles of lower limb and feet and can theoretically give a warning signal of freezing. This may help the patient prepare himself/herself,” Dr Pal adds.

How many Indians are affected by Parkinson’s?

“While recent prevalence studies are not available, the number of those affected can vary from 15-50 per 100,000 population. The average age of onset in India is around 51 years, which is almost a decade younger compared to other countries,” Dr Pal says, adding the neurology department at NIMHANS manages approximately 1,000 new patients every year. “With follow-up patients, approximately 1,500 patients are managed annually,” he says.