Development and validation of the electrosacrogram (ESG): a digital point-of-care tool for real-time neuro-sacral...

Accurate assessment of neuro-sacral function after spinal cord injury/lesion and cauda equina (SCI+) is essential for diagnosis, prognosis and early management. The current bedside standard, the digital rectal examination (DRE), is subjective, invasive, and examiner dependent. Surface electromyography (s-EMG) offers a quantitative alternative but has lacked point-of-care integration. We developed the ElectroSacroGram (ESG), a bedside digital s-EMG tool enabling real-time objective assessment of sacral somatic function after SCI+. This study aimed to (1) develop the ESG protocol based on clinical consensus; and (2) evaluate its diagnostic performance compared to radiological findings and expert-performed DRE.

In this prospective proof-of-concept diagnostic study at a specialized Level 1 trauma center, 52 adults with suspected SCI + and 21 healthy participants underwent ESG and DRE. ESG quantified sacral motor (resting external anal sphincter tone, maximal voluntary anal contraction (maxVAC), reflex (bulbospongious or bulbocavernosus reflex (BSR)), and sensory (electrical perceptual threshold (EPT)) function using low-intensity electrical stimulation. Clinically relevant DRE parameters were selected by an expert panel. Content validity was assessed using item/scale content validity indices (CVI), agreement with DRE (Cohen's κ) and diagnostic accuracy were calculated against imaging-confirmed spinal lesions.

Normative ESG values were established in healthy participants. Neurologically impaired patients showed reduced maxVAC and BSR amplitudes and elevated EPT. ESG demonstrated excellent content validity (S-CVI = 1.00), strong agreement with DRE for VAC (κ = 0.876) and EPT (κ = 0.881), and high diagnostic accuracy (sensitivity 83.3%, specificity 100%, overall accuracy 86.5%).

ESG enables precise, reproducible evaluation of sacral motor, reflex, and sensory integrity in real-time at bedside. By complementing and objectifying the DRE, it offers a promising precision-medicine tool for early neuro-sacral assessment, enhancing clinical research and improving SCI + diagnosis, for the acute phase and in the context of spinal shock.