He was an early practitioner of neuro-rehabilitation, advocating a regimen of special exercises for patients with neurological disorders.
He studied medicine at the Universities of Heidelberg and Leipzig, and was a student of neurologist Wilhelm Heinrich Erb (1840–1921).
Here he established a center of physical medicine and rehabilitation, where patients with neurological impairments could reinstate dexterity and improve mobility.
In addition, renowned neurosurgeon Otfrid Foerster (1873–1941) was greatly influenced by Frenkel's work and spent considerable time at Heiden.
[1] Frenkel died in Dresden, Germany and his body was brought to Heiden, Switzerland for burial.