Needle Electromyography Waveforms During Needle Electromyography

Denervation of rectus capitis posterior minor as neglected factor in Chiari malformation type I revealed by double blinded prospective study

Chiari malformation type I (CMI) typically manifests with Valsalva-induced occipital headaches and commonly co-occurs with syringomyelia. The disruption of cerebrospinal fluid (CSF) dynamics at the craniocervical junction (CCJ) is a key pathophysiological feature. The rectus capitis posterior minor (RCPmi), innervated by the C1 nerve root's posterior branch, significantly facilitates CSF flow at the CCJ, correlating closely with occipital headaches. This study aims to explore RCPmi functionality in CMI patients compared to healthy controls using needle electromyography (nEMG). Data from adult CMI patients and a health group collected from January 2023 to May 2024 were analyzed. Both groups underwent bilateral RCPmi nEMG testing, assessing mean duration, amplitude, multiphasic wave ratio, recruitment phase amplitude, and spontaneous potentials during Valsalva maneuvers. We conducted a double-blinded evaluation, with additional subgroup analyses based on headache presence, tonsillar herniation relative to the C1 vertebra, and syringomyelia involvement. The study included 40 CMI patients and 30 healthy controls with no demographic differences. Healthy controls displayed stable RCPmi-nEMG parameters, with intense electrical activity during Valsalva maneuvers. In contrast, CMI patients exhibited substantial denervation damage in bilateral RCPmi, particularly during Valsalva maneuvers, characterized by insufficient electrical signal response and sparse motor units. Subgroup analysis revealed increased denervation in patients with headaches, extensive tonsillar herniation, and syringomyelia involving C1. RCPmi plays a critical role in maintaining cranio-cervical stability and modulating intracranial pressure, especially during Valsalva maneuvers. Compared to controls, CMI patients show widespread denervation damage in RCPmi, strongly linked to enhanced obstruction of CCJ-CSF flow and typical headache symptoms. This denervation damage, likely related to pathological factors like C1 nerve root compression by herniated cerebellar tonsils and inflammatory mediator release at the CCJ, highlights the functional failure of RCPmi as a novel target for understanding the headache mechanism in CMI and for developing pain interventions.

A clinical decision support system for diagnosis and severity quantification of lumbosacral radiculopathy using intramuscular electromyography signals

Interpreting intramuscular electromyography (iEMG) signals for diagnosing and quantifying the severity of lumbosacral radiculopathy is challenging due to the subjective evaluation of signals. To address this limitation, a clinical decision support system (CDSS) was developed for the diagnosis and quantification of the severity of lumbosacral radiculopathy based on intramuscular electromyography (iEMG) signals. The CDSS uses the EMG interference pattern method (QEMG IP) to directly extract features from the iEMG signal and provide a quantitative expression of injury severity for each muscle and overall radiculopathy severity. From 126 time and frequency domain features, a set of five features, including the crest factor, mean absolute value, peak frequency, zero crossing count, and intensity, were selected. These features were derived from raw iEMG signals, empirical mode decomposition, and discrete wavelet transform, and the wrapper method was utilized to determine the most significant features. The CDSS was trained and tested on a dataset of 75 patients, achieving an accuracy of 93.3%, sensitivity of 93.3%, and specificity of 96.6%. The system shows promise in assisting physicians in diagnosing lumbosacral radiculopathy with high accuracy and consistency using iEMG data. The CDSS's objective and standardized diagnostic process, along with its potential to reduce the time and effort required by physicians to interpret EMG signals, makes it a potentially valuable tool for clinicians in the diagnosis and management of lumbosacral radiculopathy. Future work should focus on validating the system's performance in diverse clinical settings and patient populations.