Controversies and Clinical Applications of Non-Invasive Transspinal Magnetic Stimulation: A Critical Review and Exploratory Trial in Hereditary Spastic Paraplegia

Abstract

Magnetic stimulation is a safe, non-invasive diagnostic tool and promising treatment strategy for neurological and psychiatric disorders. Although most studies address transcranial magnetic stimulation, transspinal magnetic stimulation (TsMS) has received recent attention since trials involving invasive spinal cord stimulation showed encouraging results for pain, spasticity, and Parkinson’s disease. While the effects of TsMS on spinal roots is well understood, its mechanism of action on the spinal cord is still controversial. Despite unclear mechanisms of action, clinical benefits of TsMS have been reported, including improvements in scales of spasticity, hyperreflexia, and bladder and bowel symptoms, and even supraspinal gait disorders such as freezing and camptocormia. In the present study, a critical review on the application of TsMS in neurology was conducted, along with an exploratory trial involving TsMS in three patients with hereditary spastic paraplegia. The goal was to understand the mechanism of action of TsMS through H-reflex measurement at the unstimulated lumbosacral level. Although limited by studies with a small sample size and a low to moderate effect size, TsMS is safe and tolerable and presents consistent clinical and neurophysiological benefits that support its use in clinical practice.

Trans‐Spinal Theta Burst Magnetic Stimulation in Parkinson's Disease and Gait Disorders

“…Putative mechanism of TsMS in PD would be similar to SCS, 7 either by direct dorsal column stimulation or by synchronous activation of several tactile afferents, mostly at multiple dorsal roots. 12 Because we defined stimulation intensity by motor root stimulation, intensity might not have been sufficient to properly activate afferents or spinal cord tracts. The selection of the upper thoracic level was inspired by previous invasive SCS studies conducted at this level, which reported improvements in gait and FOG in PD.…”

“…Trans‐spinal magnetic stimulation (TsMS) is an emerging method that can affect spinal circuitry noninvasively and has shown promise in alleviating motor symptoms of PD, with the benefit of safety and cost in comparison to SCS 12 . Following a previous pilot study showing positive effects of TsMS in patients with PD and gait disorders, 13 we report here a phase II clinical trial on the effects of intermittent θ‐burst (iTB) TsMS on gait, balance, and other motor symptoms.…”

Non-pharmacological treatment of hereditary spastic paraplegia: a systematic review

“…In the only open-label pilot available trial, the authors enrolled 3 patients with a definite genetic diagnosis of HSP [ 42 ]. All patients underwent a single session of transspinal magnetic stimulation (TsMS) at the level of the second thoracic vertebra by a continuous theta burst session of a hundred three-pulse bursts at 50 Hz repeated after a 90-min interval using a figure-eight coil and at 100% of the motor threshold.…”