Intrafusal effects of botulinum toxin in post‐stroke upper limb spasticity

Trompetto, Carlo; Bove, Marco; Avanzino, Laura; Francavilla, G.; Berardelli, Alfredo; Abbruzzese, Giovanni

doi:10.1111/j.1468-1331.2008.02076.x

Cited by 32 publications

(23 citation statements)

References 15 publications

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“…Since M-wave amplitudes are expected to be reduced after BoNT-A injection [18], we used the M-wave values obtained at baseline condition to normalise the SR amplitudes elicited before and after the treatment.…”

Section: Discussionmentioning

confidence: 99%

Manual Linear Movements to Assess Spasticity in a Clinical Setting

et al. 2013

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In a clinical setting, where motor-driven systems are not readily available, the major difficulty in the assessment of the stretch reflex lies in the control of passive limb displacement velocity. A potential approach to this problem arises from the use of manual sinusoidal movements (made by continuous alternating flexions and extensions) paced by an external stimulus. Unfortunately, there are conditions in which sinusoidal movements induce interfering phenomena such as the shortening reaction or postactivation depression. In the present paper, a novel manual method to control the velocity of passive linear movements is described and the results obtained from both healthy subjects and spastic patients are reported. This method is based on the synchronisation of movements with tones played by a metronome at different speeds. In a first set of experiments performed in healthy subjects, we demonstrated consistent control of velocity during passive limb movements using this method. Four joints usually examined during muscle tone assessment were tested: wrist, elbow, knee and ankle joints. Following this, we conducted a longitudinal assessment of the stretch reflex amplitude in wrist flexor muscles in patients with spasticity treated with botulinum toxin type A. The evaluators were not only able to vary the movement velocity based on the metronome speed, but also could reproduce the respective speeds two weeks later, despite the changing degree of hypertonia. This method is easy to perform in a clinical setting and hardware requirements are minimal, making it an attractive and robust procedure for the widespread clinical assessment of reflex hypertonia.

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Section: Discussionmentioning

confidence: 99%

Manual Linear Movements to Assess Spasticity in a Clinical Setting

et al. 2013

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“…Results from animal and human studies suggest that the toxin may work in complex ways at many levels and with different time courses 38. For instance, the duration of the effects on neuromuscular junction and muscle spindles are different: maximal voluntary contraction and direct M‐wave fully recovers in 3 to 4 months, while a reduced sensitivity to proprioceptive stimulation can still be visible even 7 months later 17, 39. Therefore, besides its action at the neuromuscular junction, the toxin most likely alters sensory inputs to the CNS acting on motor gamma endings, thus modifying spindle afferent discharges from the injected muscle.…”

Section: Discussionmentioning

confidence: 99%

Cervical dystonia affects aimed movements of nondystonic segments

et al. 2009

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Patients with focal dystonia exhibit proprioception abnormalities that can lead to kinematic deficits. Proprioceptive abnormalities are present in both symptomatic and asymptomatic body parts of dystonic patients. To ascertain whether in patients with idiopathic cervical dystonia (CD) movements performed with nondystonic segments display kinematic abnormalities, we studied trajectory formation of out and back arm reaching movements in 10 patients with CD (before and 3 weeks after treatment with Botulinum toxin) and in 10 age-matched controls. Before treatment, patients with CD showed significant trajectory abnormalities when compared with normal controls. Patients' trajectories were more curved with asymmetrical temporal velocity profiles as well as increased hand path areas, and had longer reversal lags between the out and back segments. Treatment with botulinum toxin improved all the kinematic parameters. These results suggest that in patients with CD, movements performed with nondystonic segments are abnormal. The kinematic abnormalities are likely to derive from long-standing defective integration of the proprioceptive input, which, in turn, causes general changes in the internal models of limb dynamics. It is plausible that treatment with botulinum toxin partially restores proprioceptive processing and thus, such internal models.

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“…Furthermore, BoNT A may display a varying effect on spastic and volitional contraction depending on its concurrent action on extrafusal and intrafusal motor end plates. 9, 10 The precise mechanical impact of BoNT A injections on the stretch reflex and voluntary motor command is poorly understood. The clinical scales used in the literature (Ashworth and Tardieu) are not sensitive enough to quantitatively assess BoNT A's effect on the stretch reflex.…”

Section: Introductionmentioning

confidence: 99%