University Hospitals

Hesham Abboud

The utilization of advanced technology to modulate the central or peripheral nervous system in patients with neurological disorders has expanded significantly over the past three decades. Neuromodulation techniques provide a novel alternative to medical therapy for symptom management and restoration of neurological function. The ability to cope with disease progression and symptom fluctuation while avoiding the harmful side effects of drug therapy and chemical dependence has made neuromodulation an attractive therapeutic intervention in modern clinical neurology.

Deep brain stimulation (DBS) has revolutionized symptom management in patients with essential tremor, Parkinson’s disease, and primary dystonia. New DBS indications are being explored in stroke, multiple sclerosis, Tourette’s syndrome, major depression, and obsessive-compulsive disorder. Spinal cord stimulation (SCS) provides a safer alternative to opioids in patients with chronic neuropathic pain secondary to failed back syndrome, multiple sclerosis, or thalamic pain syndrome.

Likewise, sacral neuromodulation (bladder stimulator) has shown efficacy in patients with neurogenic bladder and/ or bowel incontinence secondary to various neurological conditions. These electrical neural stimulators can be inserted relatively easily and are fully programmable after surgical implantation. The electrical signal can be adjusted to cope with symptom severity and disease progression. Programming can also mitigate any stimulation-related side effects. Most of the newer models of neural stimulators are compatible with magnetic resonance imaging and come with easy-to-use software platforms.

In patients with severe diffuse spasticity, the use of intrathecal baclofen pump (ITB) can provide symptom relief without significant sedation in patients who are refractory to or intolerable to high doses of oral muscle relaxants. Unlike neural stimulators, the neuromodulation in ITB relies on targeted chemical inhibition of the spinal cord by delivering baclofen directly into the intrathecal space to reduce muscle tone and ameliorate spasms.

ITB has been used successfully in patients with multiple sclerosis, stroke, and traumatic brain or spinal cord injury. It is being explored in patients with other genetic and/or neurodegenerative conditions that result in spasticity. Other neuromodulation techniques that have shown promise in various neuropsychiatric indications include transcranial magnetic stimulation (for depression, pain, tremor, and diagnostic indications), peripheral nerve stimulation (for pain, foot drop, and bladder dysfunction), and the brain-computer interface (for paralysis and/or sensory or visual loss).

Neuromodulation techniques do not come without side effects. Off-target stimulation, hardware infection, and circuit malfunction are a few examples of the possible adverse events. In addition, the current technology provides only partial symptom relief and some patients may not respond at all to neuromodulation. More research is needed to refine the efficacy, efficiency, and safety of neuromodulation. Expanding the indication list and creating new neuromodulation interventions including patient-operated and closed-loop techniques are among the future goals of the field. Unlike other clinical specialties, organ transplantation and artificial organs are not feasible in neurological disorders. Therefore, there is a great need for creative, technology-based, alternative solutions to improve the quality of life and the welfare of neurological patients.