PUSHING
BOUNDARIES
NEUROMODULATION In Full Bloom
by Vasudeva Iyer, MD
While I was strolling in the shopping mall, a middle-aged woman stopped me and asked the usual question:“ Don’ t you remember me? I was your patient four or five years ago.” Out of politeness, I asked how she was doing. She started narrating her story quite enthusiastically. Apparently, she was referred by her orthopedics doctor for EMG evaluation of foot drop. She recalled that I did several tests and diagnosed her with multiple sclerosis. Since she had spastic foot drop( with intact peripheral nerve and muscle), I sent her to a facility where she could get a bioelectric device which significantly improved her gait. This episode made me ponder over the tremendous advances in the fields of“ bioelectronic medicine” and“ neuromodulation.”
The term neuromodulators refer to numerous amines and neuropeptides that strength of synaptic connections and thereby influence neuronal networks. According to the International Headache Society, a neuromodulation device“ modulates the activity of the brain, the spinal cord or peripheral nerves by means of electricity, magnetic fields or other device, to either inhibit or stimulate neural impulses to achieve a clinical benefit to patients.” Such devices may use not only electrical stimulation, but also magnetic, ultrasound and chemical stimulation. Virtually any stimulus that can induce release of the various neurotransmitters and thereby alter / modulate the functional status of peripheral / central neurons can be considered neuromodulation.
The ancient Egyptians and Romans apparently used the electric torpedo fish to treat pain. With the advent of electricity storage devices in the mid-18th century, electrical stimulation became much more popular. Ronald Melzack and Patrick Wall in 1965 proposed that the spinal cord has a“ gate” that can block pain signals from reaching the brain: input from large axons that carry non-nociceptive stimuli can close the gate and block nociceptive signals carried by small C axons. Transcutaneous nerve stimulators( TENS) which selectively stimulate the non-nociceptive fibers evolved from this concept. Electric stimulation of the brain has a different story. Ladislas Meduna, a Hungarian neuropathologist and psychiatrist, is credited with formulating the concept that seizures might treat psychiatric disease. He based this on his observation that microglial concentrations were greater in brains of patients with epilepsy compared to those of schizophrenia. He ex-
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