WEEK 2 Lecture 2.2 PTY 223 Introduction to motor neuron lesions.pptx

Introduction to Upper Motor Neuron Lesion Lecture 2.2 BPT 223 Physiotherapy – Neurology (Theory) fchs.ac.ae  Objectives 1 2...

Introduction to Upper Motor Neuron Lesion Lecture 2.2 BPT 223 Physiotherapy – Neurology (Theory) fchs.ac.ae  Objectives 1 2 3 4 5 Define motor Review Identify the Distinguish Classify the neuron anatomy of key features of between UMN conditions UMN and LMN UMN and LMN and LMN related to UMN dysfunction dysfunction and LMN dysfunction 2 fchs.ac.ae  The Nervous System ANS- Autonomic Sympathetic and CNS parasympathetic The brain and systems spinal cord regulating internal organs PNS Nerve roots and peripheral nerves 3 fchs.ac.ae  Upper Motor UMN lesions Neuron NMJ Muscle LMN An upper motor neuron lesion is a lesion of the neural pathway above the anterior horn of the spinal cord or motor nuclei of the cranial nerves. UMN lesions may occur in cortex, internal capsule, brain stem or spinal cord Eg: Stroke, Head injury, Brain tumour (Covered this semester) spinal cord injury, MS- Multiple Sclerosis (Covered next semester) 4 fchs.ac.ae  Upper LMN lesions Motor Neuron NMJ Muscle LMN LMN lesions may occur in Spinal cord, Nerve plexus and Peripheral Nerves Conditions: Guillian Barre’ Syndrome, Motor neuron disease, Plexus Injuries (eg:Erb’s palsy), Peripheral nerve injury (Crutch palsy) – all the topics will be covered next semester 5 fchs.ac.ae  Clonus refers to a neurological condition in which the nerve cells that control the muscles are damaged and send faulty signals. UMN v LMN lesions UMN LMN Weakness Weakness Spasticity, hypertonus ↓ tone (‘floppy’) No wasting (disuse Wasting atrophy/decrease in muscle size due to no longer in use may arise) No fasciculation/a brief Muscle fasciculation may be spontaneous contraction affecting a present small number of muscle fibres, often causing a flicker of movement under the skin. 6 Hyperreflexia Hyporeflexia fchs.ac.ae  UMN Lesions Weakness. Upper motor neuron disorders produce a graded weakness of movement (paresis), which differs from the complete loss of muscle activity caused by paralysis (plegia). Weakness – the extensors are weaker than the flexors in the arms, but the reverse is true in the legs Hypertonia. Upper motor neuron disorders result in an increase in muscle tone. The higher firing rate causes an increase in the resting level of muscle activity, resulting in hypertonia. 7 fchs.ac.ae Physiological changes associated with lack of muscle activity and joint movement (weakness) Changes in cross bridge connections Connective tissue: water loss & collagen deposition Proliferation of fatty tissue within joint space Cartilage atrophy Weakening of ligament insertion sites osteoporosis 8 fchs.ac.ae  Spasticity “a motor disorder characterised by a velocity dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks (phasic stretch reflex) resulting from hyper excitability of the stretch reflex” Spasticity is a condition in which muscles stiffen or tighten, preventing normal fluid movement. The muscles remain contracted and resist being stretched, thus affecting movement, speech and gait. 9 fchs.ac.ae Testing Spasticity of the upper Limb: https://neurologicexam.med.utah.edu/adult/html/motor_abnorm al.html#02 10 fchs.ac.ae  UMN syndrome A collection of symptoms, the textbooks describe: Positive features: Negative features: – Spasticity (reflex – muscle weakness hyperexcitability) – Slowness of muscle – Resistance to passive activation movement (hypertonus) – Loss of dexterity 11 fchs.ac.ae  Clinical signs of reflex hyper-excitability Clasp-knife phenomenon – velocity dependent with increased tone felt in the initial part of the movement during PROM Exaggerated (increased) tendon jerk Clonus - Sometimes the stretch reflex is so strong that the muscle contracts a number of times in a 5-7 Hz oscillation when the muscle is rapidly stretched and then held at a constant length. This abnormal oscillation, called clonus, can be felt by the clinician. https://www.youtube.com/watch?v=PPPgTq3L6k4 12 fchs.ac.ae Clinical signs of exaggerated cutaneous reflexes Flexor withdrawal reflex Extensor & flexor spasms (esp SCI) Babinski (extensor plantar) response – toe extension evoked by a stimulus to plantar surface of foot http://library.med.utah.edu/neurologicexam/html/motor_abnormal.html#07 13 fchs.ac.ae  Hypertonicity Spasticity is NOT the same as hypertonia Increased resistance to passive movement of a muscle that is NOT velocity dependant can also occur following UMN lesion. This is defined as HYPERTONICITY (tone). The causes of this muscle stiffness or hypertonicity are secondary adaptive changes in the muscle and connective tissue in the presence of neural impairments. 14 fchs.ac.ae Mechanisms underlying hypertonia development Carr & Shepherd, 2010 15 fchs.ac.ae Secondary Motor Adaptations Muscle fibre changes post CNS lesion*: Minimal spasticity => Atrophy of both Type I and Type II fibres Severe spasticity => Type II fibres severely atrophy, Type I remain unaffected or have hypertrophy Type I & Type II Muscles will also shorten in length 16 *Lack of agreement across literature fchs.ac.ae  Contracture Connective tissues, muscle fibre types and intrinsic properties can all result in….. CONTRACTURE FORMATION Contracture is measured by assessing PROM 17 fchs.ac.ae Focus on the word ‘Motor’ while referring to the key features All the features are related to motor – mainly musculoskeletal system No sensory has been discussed with motor lesions although sensory changes are involved in most neurological conditions fchs.ac.ae Questions fchs.ac.ae