Massimo Frascarelli

Peroneus Longus Muscle Activation Pattern During Gait Cycle in Athletes Affected by Functional Ankle Instability A Surface Electromyographic Study

Background Functional ankle instability is a clinical syndrome that may develop after acute lateral ankle sprain. Although several causes of this functional instability have been suggested, it is still unclear what the activation pattern of the peroneus longus muscle is in patients with functional ankle instability. Hypothesis Peroneus longus activation patterns differ in the injured side and the uninjured side in subjects with functional ankle instability. Study Design Descriptive laboratory study. Methods The authors examined 14 subjects with functional ankle instability by using surface electromyography during walking. Activation time of the peroneus longus muscle was expressed as a percentage of the stance phase of the gait cycle. Results A statistically significant decrease in peroneus longus muscle activity was found in the injured side compared with the uninjured side (22.8% ± 4.25% vs 37.6% ± 3.5%, respectively). Conclusions Results obtained in this study show a change in peroneus longus muscle activation time after injury. Independent of the origin of this change, which could only be surmised, the decrease in peroneus longus muscle activity may result in reduced protection against lateral sprains. Clinical Relevance The assessment of peroneus longus activation pattern during gait is useful to design an appropriate rehabilitation program in athletes suffering from functional ankle instability.

Kinematic and Electromyographic Study of the Nociceptive Withdrawal Reflex in the Upper Limbs during Rest and Movement

This study set out to evaluate nociceptive withdrawal reflex (NWR) excitability and the corresponding mechanical response in the upper limbs during rest and movement. We used a three-dimensional motion analysis system and a surface EMG system to record, in 10 healthy subjects, the NWR in eight upper limb muscles and the corresponding mechanical response in two experimental conditions: rest and movement (reaching for, picking up, and moving a cylinder). The NWR was elicited through stimulation of the index finger with trains of pulses delivered at multiples of the pain threshold (PT). We correlated movement types (reach-to-grasp, grasp-and-lift), movement phases (acceleration, deceleration), and muscle activity types (shortening, lengthening, isometric) with the presence/absence of the NWR (reflex-muscle pattern), with NWR size values, and with the mechanical responses. At rest, when the stimulus was delivered at 4× PT, the NWR was present, in all muscles, in >90% of trials, and the mechanical response consisted of wrist adduction, elbow flexion, and shoulder anteflexion. At this stimulus intensity, during movement, the reflex-muscle pattern, reflex size, and mechanical responses were closely modulated by movement type and phase and by muscle activity type. We did not find, during movement, significant correlations with the level of EMG background activity. Our findings suggest that a complex functional adaptation of the spinal cord plays a role in modulating the NWR in the transition from rest to movement and during voluntary arm movement freely performed in three-dimensional space. Study of the upper limb NWR may provide a window onto the spinal neural control mechanisms operating during movement.

Vincristine neuropathy: neurophysiological and genetic studies in a case of Wilms tumor.

We report a 10‐year‐old female with Wilms tumor (WT) who developed severe neuropathy after the fifth weekly dose of vincristine. The girl was previously asymptomatic and the family history was negative for inherited neuropathies. Neurophysiological studies and electrodiagnostic findings were suggestive of a axonal neuropathy with greater motor than sensory characteristics not typical of Charcot–Marie–Tooth (CMT) Type 1A. Genetic studies were performed in view of the degree of neurotoxicity. Duplication of 17p11.2 was found that supported the diagnosis of CMT Type 1A. The patient is alive without disease and with minimal weakness of the lower extremities after 42 months. Neurophysiological studies, repeated at 8 and 24 months, were negative. Although the association of asymptomatic CMT and vincristine neuropathy has been previously reported, the present case is of note because the reversible neuropathy occurred after five doses of vincristine, suggesting that possible more people suffering vincristine neurotoxicity may have underlying and asymptomatic CMT.

Entrapment neuropathy in patients with spastic cerebral palsy

Objectives –  We performed nerve conduction and needle electromyographic tests in 29 patients with spastic cerebral palsy (SCP) and severe limb deformities. Nerve conduction abnormalities were detected in 32 of 400 sensory or motor nerves, while 11 of 29 patients (37.9%) showed abnormal nerve conduction, indicating one or more entrapment neuropathies. Patients with SCP develop severe joint contractures and deformities due to spastic muscle tone and limited muscle and joint use/flexibility; these contractures and deformities can, in turn, cause nerve damage, possibly as a result of the stretching, angulation or compression mechanisms in the anatomic fibro‐osseous passages, where nerves are particularly susceptible.