Abnormal spinal interactions from hand afferents to forearm muscles in writer’s cramp

Lourenço, Gisele Caroline Urbano; Bleton, Jean-Pierre; Iglesias, Caroline; Vidailhet, Marie; Marchand‐Pauvert, Véronique

doi:10.1016/j.clinph.2007.07.009

Cited by 8 publications

(8 citation statements)

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“…This suggests a potent role of these neurones in sensory‐motor integrations during hand movements. Since there is no evidence for a possible modification of peripheral inputs, either in group I inputs (see below) and cutaneous inputs from the ulnar field (Lourenço et al 2007 b ), it has been suggested that modifications at this level might reflect changes in descending drive to inhibitory propriospinal neurones.…”

Section: Discussionmentioning

confidence: 99%

“…This could account for the weak increase seen between controls and normal‐posture patients (Fig. 5; Lourenço et al 2007 b ).…”

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confidence: 96%

“…2, ECR EMG activity after ulnar nerve stimulation (2 MT) in one control subject. From Lourenço et al (2007 b ), with permission of Elsevier.…”

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confidence: 99%

“…In control subjects, EMG suppression was smaller on the left (non‐dominant) than on the right side but there was no difference between sides in the dystonic patients. The ulnar‐induced inhibition in ECR was thus depressed on the patients' dystonic side, without any link with the clinical score or their wrist posture during handwriting (Lourenço et al 2007 b ). This result further supports the view that there is a loss of central inhibition at the spinal level in writer's cramp (see Hallett, 2006).…”

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confidence: 99%

“…These abnormal wrist postures were only manifest during handwriting, but not during the tonic contraction tested here. From Lourenço et al (2007 b ), with permission of Elsevier.…”

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confidence: 99%

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Properties of human spinal interneurones: normal and dystonic control

Marchand‐Pauvert

Iglesias

2008

The Journal of Physiology

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The muscles that control wrist posture receive large inputs from reflexes driven by hand afferents. In several studies, we have investigated these reflexes by electrical stimulation of cutaneous (median nerve) and proprioceptive (ulnar nerve) afferents from the hand. Median stimulation produced short latency inhibition in all motor nuclei investigated, possibly through inhibitory propriospinal-like interneurones. Ulnar stimulation produced similar inhibition but only in wrist extensors. In the other motor nuclei, ulnar stimulation produced short latency excitation mediated by group I motoneuronal drive through both monosynaptic and non-monosynaptic pathways involving excitatory propriospinal-like interneurones. This was followed by late excitations mediated through spinal group II and trans-cortical group I pathways. These results show that these pathways are concerned with the integration of afferent inputs, proprioceptive and cutaneous, to control of wrist posture during hand movements. Patients with focal hand dystonia exhibit abnormal postures. To investigate whether these spinal pathways contribute to these conditions, the effects of ulnar stimulation on wrist muscle activity during voluntary tonic contraction were examined in patients who suffer writer's cramp. Ulnar-induced inhibition of the wrist extensors was reduced on the dystonic side of patients compared with their normal side and controls. In patients who exhibited abnormal wrist posture, group II excitation of the wrist flexors was also modified on the dystonic side. Cutaneous stimuli, by contrast, increased wrist flexor EMG on both sides and only in patients who exhibited normal posture. We conclude that spinal interneurones have a significant role in integrating afferent inputs from the hand to control wrist posture during hand movements and that altered function in these spinal networks is associated with the complex pathophysiology of writer's cramp.

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Section: Discussionmentioning

confidence: 99%

“…This could account for the weak increase seen between controls and normal‐posture patients (Fig. 5; Lourenço et al 2007 b ).…”

mentioning

confidence: 96%

“…2, ECR EMG activity after ulnar nerve stimulation (2 MT) in one control subject. From Lourenço et al (2007 b ), with permission of Elsevier.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…These abnormal wrist postures were only manifest during handwriting, but not during the tonic contraction tested here. From Lourenço et al (2007 b ), with permission of Elsevier.…”

mentioning

confidence: 99%

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