Impaired Ability to Suppress Excitability of Antagonist Motoneurons at Onset of Dorsiflexion in Adults with Cerebral Palsy

Abstract

We recently showed that impaired gait function in adults with cerebral palsy (CP) is associated with reduced rate of force development in ankle dorsiflexors. Here, we explore potential mechanisms. We investigated the suppression of antagonist excitability, calculated as the amount of soleus H-reflex depression at the onset of ankle dorsiflexion compared to rest, in 24 adults with CP (34.3 years, range 18–57; GMFCS 1.95, range 1–3) and 15 healthy, age-matched controls. Furthermore, the central common drive to dorsiflexor motoneurons during a static contraction in the two groups was examined by coherence analyses. The H-reflex was significantly reduced by 37% at the onset of dorsiflexion compared to rest in healthy adults (P < 0.001) but unchanged in adults with CP (P = 0.91). Also, the adults with CP had significantly less coherence. These findings suggest that the ability to suppress antagonist motoneuronal excitability at movement onset is impaired and that the central common drive during static contractions is reduced in adults with CP.

The motor cortex uses active suppression to sculpt movement

“…The antagonist suppression was rediscovered by Hufschmidt and Hufschmidt ( 3 ) and is often referred to as the “Hufschmidt phenomenon” ( 4 , 5 ). The premovement suppression of antagonist muscle activity is essential for normal motor control; its impairment in Huntington’s disease and cerebral palsy is associated with striking motor disability ( 6 , 7 ).…”

Tone Reduction and Physical Therapy: Strengthening Partners in Treatment of Children with Spastic Cerebral Palsy

“…• The use of BoNT reduces spasticity and therefore provides a window of opportunity for muscle function and activitybased training. 14,20,39,40 • In the lower limb, specific gait training and active functional training are essential parts of the training process. 27,31,38,39,43,44 • In the upper limb, bimanual training of repetitive functional activities are recommended.…”

“…It reduces the potential decrease in muscle volume associated with the use of BoNT and should optimally include the injected muscles, build up progressively. 14,37,40,56,57…”

“…14 Motor learning in this group will have to involve de-learning of the unwanted patterns of co-contractions, preferably at a young age. [14][15][16][17][18] Inhibition is of course only one part of the process, as it will have to be followed by learning a more efficient pattern of movement, which is only possible with the appropriate muscle strength and predictive coding of the sensory consequences of movement. [14][15][16][17][18] This underlying mechanism illustrates the needs for a multimodal, combined treatment approach, combining appropriate tone reduction with different physical therapy (PT) approaches and techniques.…”

“…[14][15][16][17][18] Inhibition is of course only one part of the process, as it will have to be followed by learning a more efficient pattern of movement, which is only possible with the appropriate muscle strength and predictive coding of the sensory consequences of movement. [14][15][16][17][18] This underlying mechanism illustrates the needs for a multimodal, combined treatment approach, combining appropriate tone reduction with different physical therapy (PT) approaches and techniques. [16][17][18][19][20][21][22][23][24][25][26][27] Although tone reduction and PT are generally considered as strengthening partners, to the best of our knowledge, there are no specific international guidelines to support this combined approach in clinical practice.…”