I. Spasticity: A few reminders
Spasticity is a common and disabling sequela of neurological accidents. It results from damage to the pyramidal system, such as following a stroke, multiple sclerosis, spinal cord injury (para/tetraparesis/plegia), cerebral palsy (CP, CP), etc.
This so-called positive symptom of pyramidal syndrome is defined by an increased tonic stretch reflex, which is velocity-dependent. This pyramidal hypertonia is elastic like a spring: resistance increases with the speed of stretching. This means that the muscle contracts reflexively with exaggerated force during a rapid stretch.
This spasticity upon stretching is quantifiable (Ashworth, Held and Tardieu scales, etc.) at the patient's bedside. It is therefore the reference clinical criterion that allows for the quantification of this motor neuron hyperexcitability.
II. Spasticity: What are the repercussions?
This hypertonia may be necessary to maintain certain functions but can also be disabling for the musculoskeletal system.
Following a stroke, it is described as the first sign of the beginnings of motor function.
Muscle hypertonicity is sometimes the only motor capacity that can be mobilized to ensure postural maintenance; for example, spasticity of the quadriceps allows for locking of the knee and therefore an upright position.
Spasticity also exhibits significant variability in intensity, depending on individual emotional and environmental factors (stress, heat/cold, etc.). It is also exacerbated by irritants (cutaneous such as pressure sores, visceral such as bladder distension, or the presence of infections). It then serves as a warning signal from the body that should be heeded, especially in patients with sensory impairment.
Muscle spasms associated with spasticity are often described by patients as painful cramps. This is compounded by the pain caused by the abnormal position in which a limb is held due to the spasticity. Indeed, when a spastic muscle is permanently contracted and no longer stretched, the muscle fibers shorten over time, and the muscle retracts. This leads to stiffness, or even joint ankylosis, placing the limb in an abnormal position and increasing the sensitive pressure points that can lead to pressure sores. This hypertonia, which the patient cannot control, prevents any movement of the affected limb; it is immobilized.
In cases of "moderate" spasticity, ankylosis is less common. However, this spasticity causes daily motor difficulties. In addition to fatigue, the contraction of antagonistic muscles becomes more difficult: they must overcome the lack of relaxation in the spastic muscles to move a joint.
In the lower limbs, the affected muscles are generally those of the extensor chain (strochlear triceps, quadriceps, and adductors). Motor disorders then manifest during walking: slowness, instability, altered gait (a "robotic" gait), and an inability to place the foot on the ground. There are also difficulties standing and reduced comfort (when lying down or sitting).
In the upper limbs, the muscles affected by spasticity are generally those of the flexion chain (pectoralis major, biceps brachii, brachialis, carpal flexors, pronators, finger flexors, and adductor pollicis). Spasticity of the upper limbs can have significant daily consequences: the hand may be non-functional, and an upper limb folded in on itself complicates or even prevents many activities, such as eating, washing, and dressing. Motor impairments result in a lack of dexterity or significant fatigue.
Spasticity therefore has a strong impact on the comfort and quality of life of patients, especially since it is totally variable and therefore unpredictable depending on the various daily situations.
III. Spasticity: What treatments are available?
There are different types of therapeutic strategies to combat spasticity: sensorimotor rehabilitation with inhibition of spasticity (Bobath, stretching, motor vibrations), functional electrostimulation, pharmacological management (oral antispastics), botulinum toxin injection or even surgical management (placement of baclofen pump, neurotomy).
Their objectives are, for all of them, to increase motor control on the one hand and, on the other hand, to reduce segmental spasticity as needed in order to restore a desired motor function.
The Allyane method now offers a new, non-invasive approach to managing spasticity. It is a complementary rehabilitation tool that allows for short- and medium-term clinical results.
Indeed, the contribution of neuroscience has revealed that the brain possesses great capacities for adaptation and recovery (cerebral and neuronal plasticity). [1], [2]
Proprioceptive stimulation in the development of movement is well established. [3] [4]
On the other hand, mental imagery, and more specifically motor imagery, allows for the maintenance of neuro-sensory (primarily visual) input and motor performance through cortical training. [5], [6], [7], [8].
Specific low-frequency sounds, generated by a medical device, will increase the emission of alpha brain waves, allowing for hyperactivation of motor areas.
This is why the patient's proprioceptive sensations are integrated into motor imagery, coupled with low-frequency sounds. Through this method, it is the image of the movement that we seek to correct or recreate.
The Allyane method for managing triceps surae spasticity results in an average reduction of 1,41 points in the Ashworth score, achieved in 91% of treated patients and maintained at one month in 70% of them. [9] [10] [11].
References:
[1] Cofemer: Rode G, Jacquin-Courtois S, Yelnik A. Rehabilitation of strokes; page 13. September 2008.
[2] Jeannerod M. Plasticity of the motor cortex and motor recovery. Cerebral Motor Skills, vol.27, n°2, pp.50-56. 2006.
[3] Formento E, Minassian K, Wagner F, Mignardot JB, Le Goff-Mignardot CG, Rowald A, Jocelyne Bloch J, Micera S, Capogrosso M, Courtine G. Electrical spinal cord stimulation must preserve proprioception to enable locomotion in humans with spinal cord injury. Nature neuroscience Oct 2018
[4] Avanzino L, Bassolino M, Pozzo T, Bove M. Use-dependent hemispheric balance, J Neurosci, 2011, vol. 31 (pgs. 3423-3428)
[5] Oostra KM, Oomen A, Vanderstraeten G, Vingerhoets G. Influence of motor imagery training on gait rehabilitation in sub-acute stroke: A randomized controlled trial. J Rehabil Med. 2015 Mar;47(3):204-9. doi: 10.2340/16501977-1908
[6] Mateo S, Di Rienzo F, Bergeron V, Guillot A, Collet C, Rode G. Motor imagery reinforces brain compensation of reach-to-grasp movement after cervical spinal cord injury.Front Behav Neurosci. 2015 Sep 11;9:234. doi: 10.3389/fnbeh.2015.00234. eCollection 2015. Review
[7] Ehrsson H., Geyer S., Naito E. – Imagery of voluntary movements of fingers, toes and tongue actvates corresponding body-part specific motor representations – Journal of Neurophysiology, n°90, 2003, pp.3304-3316
[8] Rulleau T, Toussaint L. Motor imagery in rehabilitation. Kinesither Rev. Apr 2014
[9] Chatain AL, Impact of neuro-cognitive reprogramming in spasticity rehabilitation. Accepted poster in the ESO-WSO Virtual Conference, November 7-9, 2020
[10] Chatain AL, Contribution of neurocognitive reprogramming in the management of spasticity. Communication and e-poster at the e-JNLF 4-6 September 2020.
[11] Chatain AL, Contribution of neurocognitive reprogramming in the management of spasticity. Poster presented at the 2nd Days of the French Neuro-Vascular Society SFNV, Issy les Moulineaux, Nov 2019.