Muscle architecture and passive lengthening properties of the gastrocnemius medialis and Achilles tendon in children who idiopathically toe-walk

Children who idiopathically toe-walk (ITW) habitually operate at greater plantarflexion angles and thus, at shorter muscle-tendon unit (MTU) lengths than typically developing (TD) children. Therefore, it is often assumed that habitual use of the gastrocnemius muscle in this way will cause remodelling of the muscle-tendon architecture compared to TD children. However, the gastrocnemius muscle architecture of children who ITW has never been measured. It is essential that we gain a better understanding of these muscle-tendon properties, to ensure that appropriate clinical interventions can be provided for these children. Five children who ITW (age 8 ± 2 years) and 14 TD children (age 10 ± 2 years) participated in this study. Ultrasound was combined with isokinetic dynamometry and surface electromyography, to measure muscle architecture at common positions and passive lengthening properties of the gastrocnemius muscle and tendon across full range of motion. Regardless of which common condition groups were compared under, both the absolute and normalised to MTU muscle belly and fascicle lengths were always longer, and the Achilles tendon length was always shorter in children who ITW than TD children (p 0.05); however, passive joint stiffness was greater in children who ITW at maximum dorsiflexion (p = 0.001) and at a joint moment common to all participants (p = 0.029). Consequently, the findings of this pilot study indicate a remodelling of the relative MTU that does not support the concept that children who ITW commonly experience muscle shortening. Therefore, greater consideration of the muscle and tendon properties are required when prescribing clinical interventions that aim to lengthen the MTU, and treatments may be better targeted at the Achilles tendon in children who ITW

Prediction and monitoring upper-extremity motor recovery after severe stroke. Clinical and neurophysiological studies.

Contains fulltext : 40151_predanmou.pdf (publisher's version ) (Open Access)Stroke is an important disease in Western Society with an estimated incidence of 30.000 patients/year in the Netherlands. In approximately 70 to 80% of the stroke survivors upper-extremity motor function is impaired and in almost one third of these patients motor impairments are severe. Among those with severe impairments, two-thirds do not regain the functional use of the affected arm or hand. Nevertheless, nearly 25% of these patients will regain partial motor recovery, and 5-20% even complete motor recovery. These 'recovery' patients, however, cannot be accurately identified by clinical assessment. The pathophysiological processes underlying motor recovery after stroke and the development of spasticity are not well understood. It seems essential to enhance our knowledge of (cortical) reorganization processes to predict motor recovery and ultimately improve the effects of various treatment approaches in stroke patients. Transcranial magnetic stimulation is a non-invasive neurophysiological technique to assess the integrity of the corticospinal pathways both objectively and quantitatively. TMS is particularly effective in the activation of distal hand muscles in which a short-latency motor evoked potential (MEP) can be recorded by surface electromyography. Previous studies consistently showed high specificity of the presence of a MEP (100%) in those patients who will show upper-extremity motor recovery. There is also some evidence that TMS may be of value in predicting the development of post-stroke spasticity through information obtained from the silent period (SP). In this study, both clinical examinations and neurophysiological techniques will be used to investigate the importance of the integrity of the corticospinal pathways for upper-extremity functioning. In particular, the additional predictive value of both MEP and SP to clinical examination with regard to post-stroke hand motor recovery will be determined in patients with a severe, middle cerebral artery stroke. The development of spasticity will be monitored and predicted in these patients as well.RU Radboud Universiteit Nijmegen, 27 mei 2008Promotores : Geurts, A.C.H., Zwarts, M.J. Co-promotores : Pasman, J.W., Hendricks, H.T.191 p

Are clinical characteristics associated with upper-extremity hypertonia in severe ischaemic supratentorial stroke?

Contains fulltext : 52282.pdf (publisher's version ) (Open Access)OBJECTIVE: The primary goal of this study was to identify clinical risk factors, in addition to muscle weakness, for upper-extremity hypertonia in patients with severe ischaemic supratentorial stroke. The secondary goal was to investigate the time course of upper-extremity hypertonia in these patients during the first 26 weeks post-stroke. DESIGN: Inception cohort. PATIENTS: Forty-three consecutive patients with an acute ischaemic supratentorial stroke and an initial upper-extremity paralysis admitted to an academic hospital. MAIN OUTCOME MEASURES: Primary outcome: hypertonia assessed by the Ashworth scale at week 26 post-stroke. Potential risks factors: motor functions assessed by the upper-extremity subscore of the Fugl-Meyer motor assessment, Barthel Index at week 1, consciousness, sensory disturbances, apraxia, neglect, and hyper-reflexia. Secondary outcome: time course of upper-extremity hypertonia by assessing its prevalence at 6 consecutive moments post-stroke during a follow-up period of 26 weeks. RESULTS: Twenty-five patients (63%) developed hypertonia during the follow-up period of 26 weeks. During this period, the prevalence of hypertonia followed a rather dynamic course, with cases of early, transient and late hypertonia. Univariate analyses yielded none of the selected clinical characteristics as significantly associated with hypertonia. CONCLUSION: Despite the high incidence of hypertonia (63%) observed, none of the selected clinical characteristics could be identified as a risk factor for hypertonia

Are neuroradiological or neurophysiological characteristics associated with upper-extremity hypertonia in severe ischaemia in supratentorial stroke?

Contains fulltext : 53528.pdf (publisher's version ) (Open Access)OBJECTIVE: The primary goal was to identify the neuroradiological and neurophysiological risk factors for upper-extremity hypertonia in patients with severe ischaemic supratentorial stroke. DESIGN: Inception cohort. PATIENTS: Forty-three consecutive patients with an acute ischaemic supratentorial stroke and an initial upper-extremity paralysis admitted to an academic hospital recruited over a 1.5-year period. MAIN OUTCOME MEASURES: Upper-extremity hypertonia was assessed by the Ashworth scale and clinically relevant hypertonia was defined as Ashworth scale >or=2. Any association of (clinically relevant) hypertonia with neuroradiological (lesion side, extent of lesion, and stroke history), and neurophysiological (motor-evoked potential and silent period) characteristics was investigated. RESULTS: Associations between hypertonia and the selected neuroradiological and neurophysiological risk factors were generally low. Univariate analyses yielded none of the selected neuroradiological or neurophysiological characteristics as significantly associated with hypertonia. CONCLUSION: Despite the high incidence of hypertonia in these patients, we could not identify any of the selected neuroradiological or neurophysiological characteristics as a risk factor for hypertonia

Acute deterioration of bulbar function after botulinum toxin treatment for sialorrhoea in amyotrophic lateral sclerosis.

Contains fulltext : 69522.pdf (publisher's version ) (Closed access)Transcutaneous botulinum toxin injection in the salivary glands was introduced in 2000 as a new treatment for sialorrhoea in amyotrophic lateral sclerosis (ALS). We describe an ALS patient who developed serious complications of botulinum toxin treatment for sialorrhoea, and we review the relevant literature. A 64-yr-old woman with bulbar ALS for 6 mos was treated for disabling sialorrhoea. She had moderate dysphagia, but she was able to swallow. The submandibular and parotid glands were injected transcutaneously, under ultrasound guidance, with botulinum toxin (Dysport), 80 U on each side. Four days later, her bulbar function rapidly deteriorated, resulting in complete aphagia and anarthria on the fifth day. A PEG catheter was placed. Although according to the literature this treatment can be made safer by cautiously increasing the dosage and injecting the parotid glands first, BTX should not be the first-line treatment of sialorrhoea in ALS; comparative studies of BTX, amitryptiline, scopolamine, and radiation should be performed first

Can forearm muscle activity be selectively recorded using conventional surface EMG-electrodes in transcranial magnetic stimulation? A feasibility study.

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Supratentorial ischemic stroke: more than an upper motor neuron disorder.

The primary goal of this study was to identify secondary functional changes in the peripheral motor units of the paretic upper extremity (UE) in patients with severe ischemic stroke and to determine how these changes develop during the first weeks after stroke. An inception cohort of 27 consecutive patients with an acute ischemic supratentorial stroke and an initial UE paralysis was compared with 10 healthy control subjects. The ulnar nerve was electrically stimulated proximal to the wrist and electromyographic recordings were obtained from the abductor digiti minimi muscle. Hemiparetic side mean values of the compound muscle action potential (CMAP) 1 and 3 weeks after stroke were compared with the nonparetic side and with CMAP values obtained from healthy control subjects. The mean CMAP amplitude in patients was significantly lower on the paretic side compared with the nonparetic side and with control subjects. Decrease in CMAP amplitude was observed in more than half of the stroke patients, sometimes as early as 4 days after stroke, and persisted in most cases. Whenever present, it was accompanied by absence of motor recovery at that specific time after stroke. Decreased CMAP amplitude in the abductor digiti minimi muscle can be seen already in the very acute phases after stroke unrelated to peripheral neuropathy, radiculopathy, or plexopathy, and it is accompanied by absence of UMN recovery. This knowledge is important for interpreting electrophysiological data in stroke patients

Definition dependent properties of the cortical silent period in upper-extremity muscles, a methodological study

Contains fulltext : 127740.pdf (publisher's version ) (Open Access)BACKGROUND: To explore if stimulus-response (S-R) characteristics of the silent period (SP) after transcranial magnetic stimulation (TMS) are affected by changing the SP definition and by changing data presentation in healthy individuals. This information would be clinically relevant to predict motor recovery in patients with stroke using stimulus-response curves. METHODS: Different landmarks to define the SP onset and offset were used to construct S-R curves from the biceps brachii (BB) and abductor digiti minimi (ADM) muscles in 15 healthy participants using rectified versus non-rectified surface electromyography (EMG). A non-linear mixed model fit to a sigmoid Boltzmann function described the S-R characteristics. Differences between S-R characteristics were compared using paired sample t-tests. The Bonferroni correction was used to adjust for multiple testing. RESULTS: For the BB, no differences in S-R characteristics were observed between different SP onset and offset markers, while there was no influence of data presentation either. For the ADM, no differences were observed between different SP onset markers, whereas both the SP offset marker "the first return of any EMG-activity" and presenting non-rectified data showed lower active motor thresholds and less steep slopes. CONCLUSIONS: The use of different landmarks to define the SP offset as well as data presentation affect SP S-R characteristics of the ADM in healthy individuals

Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

Contains fulltext : 81487.pdf (publisher's version ) (Closed access)OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps brachii (BB) and abductor digiti minimi (ADM) muscles in 15 healthy participants. A nonlinear mixed model was used to fit the stimulus-response curves to a sigmoid Boltzmann function. Results : Small residuals of the function were found for MEPs and SPs in both muscles. Higher maximal MEP amplitudes were found for the BB compared to the ADM (p<0.01). The active motor threshold to obtain a SP was less for the ADM compared to the BB (p<0.01). The slope parameter of the function of the SP duration was steeper and more variable in the ADM than in the BB (p<0.01). For the MEP amplitude no difference in active motor threshold and slope of the function was found between both muscles. CONCLUSIONS: Excitatory (MEP) and inhibitory (SP) effects of TMS differ between proximal arm and distal hand muscles in healthy participants. The adequate fit of our model suggests that this model can be used to study between and within subject changes in future studies