Cala Therapy delivers patterned stimulation to the median and radial nerves at the patient’s tremor frequency. The pulse pattern of this stimulation is provided continuously in bursts tuned around 4-12 Hz, the range of hand tremor due to essential tremor. The duration of each pulse is 300 usec to selectively activate peripheral Aβ sensory nerve fibers, and the frequency of this pulse is in the range of 50-150 Hz similar to deep brain stimulation used to treat essential tremor.
Why does Cala Therapy stimulate the median and radial nerves?
The Cala Therapy team initially explored stimulation of median, radial, and ulnar nerves. While the effect on the ulnar nerve is an area of research interest, early feedback from user testing suggested median and radial nerve stimulation were preferred.
Does Cala Therapy stimulation cause nerve fatigue?
Cala Therapy stimulation is not expected to cause nerve or muscle fatigue. Stimulation-induced nerve block requires stimulation frequencies above 1,000 Hz [1], whereas the Cala Therapy uses a frequency of 150 Hz. While neurotransmitter depletion at the synapse downstream of stimulation can occur at frequencies as low as 100 Hz [1], there were no instances of loss in sensory function observed with use of Cala Therapy stimulation in the three-month PROSPECT study (n=263 patients). Long-term therapy habituation, which could be caused by synaptic changes at the brain level, was not observed over multiple months of use in the PROSPECT study.
The stimulation amplitude is set below the threshold for motor nerve fiber recruitment, so stimulation-induced muscle fatigue is not expected during typical use of Cala Therapy. The PROSPECT study showed that 0.4% of subjects had device-related weakness or lack of coordination in the treated hand.
Reference [1] Kilgore KL and Bhadra N, “Reversible nerve conduction block using kilohertz frequency alternating current,” Neuromodulation, 17(3): 242-55, 2014.
How is Cala Therapy different than TENS (transcutaneous electrical nerve stimulation)?
Cala Therapy is a first-in-class therapy. It performs a significantly different function than TENS devices in relieving hand tremor compared to pain. It is also different in how it operates by delivering a stimulation therapy called transcutaneous afferent patterned stimulation (TAPS). Cala Therapy combines these unique characteristics to provide a treatment individualized for a patient’s unique tremor.
MKG-1050 Rev P Aug 2021
MKG-1610 Rev A July 2022