Trans-spinal motor evoked potentials (TsMEP) represent a novel intraoperative neuromonitoring technique designed to localize motor deficits when transcranial motor evoked potentials (TcMEP) are lost or unreliable. This technique involves direct electrical stimulation of the spinal cord through pedicle screws using a train of biphasic square-wave pulses, with myogenic responses recorded from limb muscles. In the presented case of kyphoscoliosis correction, TsMEP was employed after TcMEP signals failed to recover despite corrective measures. Stimulation at various vertebral levels allowed TsMEP to localize the level of motor pathway compromise, guiding targeted decompression. Unlike sensory-based methods such as dynamic spinal cord mapping, TsMEP directly evaluates motor tract integrity and provides real-time, segmental information without the need for epidural instrumentation. This technique also enabled monitoring of functional recovery through threshold changes, demonstrating its clinical utility. TsMEP holds promise as an intraoperative diagnostic and decision-making tool, especially in complex spinal surgeries with high neurological risk.

BACKGROUND AND PURPOSE: Parkinson's disease (PD) and multiple-system atrophy of the parkinsonian type (MSA-P) are progressive neurodegenerative disorders that in addition to dysfunction of the motor system also present with features of dysautonomia, frequently manifesting as orthostatic hypotension (OH). The pathophysiology of OH has been proposed to differ between these two disorders. This study investigated the spontaneous and cardiovagal baroreflex sensitivity (BRS) in Parkinson's disease patients with orthostatic hypotension (PD(OH)) and multiple system atrophy of Parkinsonian type with orthostatic hypotension in an attempt to differentiate the two disorders. METHODS: Two methods were used for determining the BRS: a spontaneous method (spontaneous BRS) and the reflexive baroreflex gain (cardiovagal BRS) from phases II and IV of the Valsalva maneuver (VM) in PD(OH) and MSA-P(OH). RESULTS: The spontaneous BRS (5.04±0.66 ms/mm Hg vs. 4.78±0.64 ms/mm Hg, p=0.54) and the cardiovagal BRS from phase II of the VM (0.96±0.75 ms/mm Hg vs. 1.34±1.51 ms/mm Hg, p=0.76) did not differ between PD(OH) and MSA-P(OH), but the cardiovagal BRS from phase IV of the VM (0.03±0.07 ms/mm Hg vs. 2.86±2.39 ms/mm Hg, p=0.004) was significantly lower in PD(OH). CONCLUSIONS: The cardiovagal BRS from phase IV of the VM has potential for differentiating PD(OH) and MSA-P(OH), indicating a difference in the pathophysiological mechanisms underlying the autonomic dysfunction in the two disorders.
Atrophy* ; Baroreflex* ; Humans ; Hypotension, Orthostatic ; Multiple System Atrophy ; Neurodegenerative Diseases ; Parkinson Disease* ; Primary Dysautonomias ; Reflex ; Valsalva Maneuver