Biomechanical and electromyographic assessment of spastic hypertonus in motor complete traumatic spinal cord-injured individuals

Abstract

Study design: Between-groups design with repeated measures. Objective: To quantify spastic hypertonia in spinal cord-injured (SCI) individuals. Setting: Rehabilitative Center, Italy. Subjects: 29 individuals with a motor complete SCI (American Spinal Injury Association impairment scale grade A or B) and 22 controls. Methods: According to the modified Ashworth scale (MAS), patients were subgrouped as SCI-1 (MAS ¼ 1, 1 þ ) and SCI-2 (MAS ¼ 2, 3). Passive flexo-extensions of the knee were applied using an isokinetic device (LIDO Active) at 301, 601, 901 and 1201 s À1 . We measured the peak torque, mean torque (MT) and work. Simultaneous electromyography (EMG) was recorded from leg muscles. Results: At the speed of 1201 s À1 all SCI-2 patients presented EMG reflex activities in the hamstring muscle. All biomechanical parameter values increased significantly according to speed, but analysis of variance revealed a significant interaction between the angular velocity and group (F(d.f. 6, 138) ¼ 8.89, Po0.0001); post hoc analysis showed significantly greater torque parameter values in the SCI-2 group compared with the SCI-1 group and the control group at 901 and 1201 s À1 . Receiver operating characteristic curves showed that using peak torque values the probability of correctly classifying a patient into SCI-1 and SCI-2 was 95%, compared with 70% for MT and 68% for work. Conclusions: The isokinetic device is useful for distinguishing individuals with a high level of spastic hypertonus. Examination of EMG activity may help ascertain whether increased muscle tone is caused by reflex hyper excitability and to determine whether muscle spasm is present. Peak torque and simultaneous EMG assessment should be considered for the evaluation of individuals with SCI in the rehabilitative context, that is, in measuring therapeutic interventions.

Properties of the surface electromyogram following traumatic spinal cord injury: a scoping review

“…number and duration of burst) during ADLs and self-reported level of spasticity [ 172 ]. The subjective component and lack of reliability in reporting spasticity using the Ashworth scale have been pinpointed as a possible confounding factor in establishing a clear relation between sEMG properties and spasticity [ 173 ]. However, the use of sEMG activity was recommended to investigate reflex hyperexcitability and to determine the occurrence of muscle spasms [ 173 ].…”

“…The subjective component and lack of reliability in reporting spasticity using the Ashworth scale have been pinpointed as a possible confounding factor in establishing a clear relation between sEMG properties and spasticity [ 173 ]. However, the use of sEMG activity was recommended to investigate reflex hyperexcitability and to determine the occurrence of muscle spasms [ 173 ]. For example, sEMG measurements of involuntary activity in the lower extremity were not significantly related to perceived impact of spasticity on daily life, although spasm duration was positively associated with clinical extensor spasticity [ 174 ].…”

Protocol for rapid onset of mobilisation in patients with traumatic spinal cord injury (PROMPT-SCI) study: a single-arm proof-of-concept trial of early in-bed leg cycling following acute traumatic spinal cord injury

“…26 55 Furthermore, monitoring EMG responses will be invaluable to better understand the development of spasticity. [56][57][58] As shown in our previous animal study, 59 the main concern of introducing ABT early during the acute period is the potential risk of exacerbating spinal cord damage. However, there is a general consensus from animal studies that it can be initiated safely during the acute phase after SCI if the activity is performed in a proper environment where intense stress or supra-physiological demands from strenuous exercise are avoided.…”

“… 26 55 Furthermore, monitoring EMG responses will be invaluable to better understand the development of spasticity. 56–58 …”

Mechanical and neural changes in plantar-flexor muscles after spinal cord injury in humans

“…The Modified Ashworth Scale (MAS) is generally used to measure muscle tone and spasticity, 9 but this score lacks adequate sensitivity to distinguish the contributions from the mechanical and neural components. 10 In a study of the neural profile after SCI, we reported that spinal reflex excitability in participants experiencing both complete and incomplete SCI are significantly higher than the excitability in healthy young participants, but the Hmax/Mmax did not change significantly in incomplete SCI participants. 11 In addition, the change in Hmax/ Mmax was not associated with the chronicity of injury in SCI participants.…”