Correlating extent of neuromuscular instability with acetylcholine receptor antibodies.

In a retrospective study of 86 patients with myasthenia gravis (MG), we correlated the acetylcholine receptor (AChR) antibody titers with single-fiber EMG studies to explore whether a relationship exists between these parameters. We found that the AChR antibody titers correlated significantly with the mean of the mean consecutive difference of orbicularis oculi (OO, P<0.0001) and extensor digitorum communis (EDC, P<0.

Quantitative EMG of facial muscles in myasthenia patients with MuSK antibodies.

Objective: Our aim was to study the pathophysiological process leading to facial muscle atrophy in 13 patients with MuSK antibody positive myasthenia gravis (MuSK-MG), and to compare with findings from 12 acetylcholine receptor antibody positive myasthenia patients (AChR-MG), selected because they suffered from the same degree of disease severity and required similar treatment.

Methods: Motor unit action potential (MUAP) and interference pattern analysis from orbicularis oculi (O oculi) and orbicularis oris (O oris) muscles were studied using a concentric needle electrode, and compared with findings in 20 normal subjects, 6 patients receiving botulinum toxin injections (representing a neurogenic model) and 6 patients with a muscle dystrophy (representing a myopathic model). The techniques and control data have been reported previously.

Single-fiber electromyography in limb and facial muscles in muscle-specific kinase antibody and acetylcholine receptor antibody myasthenia gravis.

We examined the findings from single-fiber electromyography in extensor digitorum communis (EDC) and orbicularis oculi (OOc) in 13 myasthenia gravis (MG) patients with muscle-specific kinase antibodies (MuSK-MG) and 12 MG patients with acetylcholine receptor antibodies (AChR-MG) with similar clinical scores. More than 70% of AChR-MG patients had abnormal jitter in both EDC and OOc, but the majority of MuSK-MG patients had normal jitter in EDC despite abnormal jitter in OOc. These findings demonstrate clear differences between the neurophysiology of MuSK-MG and AChR-MG.

Turns amplitude analysis of the orbicularis oculi and oris muscles.

Objective: The aim of the study was to determine whether 'clouds' from turns amplitude analysis obtained from the orbicularis oculi and oris muscles without force monitoring can be used to differentiate pathological processes affecting the face.

Methods: The interference pattern from orbicularis oculi and orbicularis oris was studied using a concentric needle electrode. Data-points from 20 normal subjects were plotted on a logarithmic scale of mean amplitude between turns versus turns/second, from which linear regression analysis defined the 95% confidence intervals.

Single-fiber EMG with a concentric needle electrode: validation in myasthenia gravis.

We performed a retrospective study to validate whether a disposable concentric needle electrode (CNE) can be used in place of a single-fiber (SF) electrode for jitter measurements in myasthenia gravis (MG). Normal values for voluntary contraction of orbicularis oculi (OO) and extensor digitorum communis (EDC) were collected from 20 healthy subjects. The method was validated by a retrospective analysis of 56 consecutive MG patients, the "gold standard" being a positive acetylcholine receptor (AChR) antibody titer at the time of the electrophysiological (electromyography) study and the clinical diagnosis.