Spasticity Upper Extremity

Historical Overview

• Spasticity is a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon jerks that results from hyperexcitability of the stetch reflex as one component of upper motor neuron syndromes.¹

Description

• Upper extremity spasticity is typically defined as a velocity-dependent increase in muscle tone with an exaggeration of the stretch reflex circuitry, which is a defining characteristic of central nervous system disorders like stroke, cerebral palsy (CP), and multiple sclerosis (MS).²

Pathophysiology

• There is no single pathophysiologic mechanism that accounts for all aspects of spasticity, but paresis, soft tissue contracture, and muscle hypertonia are the 3 major mechanisms responsible for the associated motor impairment.¹
• Muscle tone regulation helps to maintain normal posture and to facilitate movement. When a muscle stretches, the neuromuscular system may respond by automatically altering muscle tone. This modulation of the stretch reflex is important in the control of motion and balance maintenance. Spasticity is manifested by increased stretch reflex, which is intensified with movement velocity. This results in excessive and inappropriate muscle activation, which can contribute to muscle hypertonia.³

Instructions

1. Obtain an accurate and complete patient history.
2. Ask the patient to lie in the supine position with their arms at their sides.
3. Passively move the upper extremity joint being evaluated (eg, shoulder, elbow, or wrist) through its full range of motion (ROM).
4. When testing a muscle that primarily flexes a joint, place the joint in a maximally flexed position and then move it to a position of maximal extension.
5. When testing a muscle that primarily extends a joint, place the joint in a maximally extended position and then move it to a position of maximal flexion.

Related Signs and Tests

• Modified Tardieu Scale
• Modified Ashworth Scale
• Dynamometer coupled with electrophysiological measurements
• Electromyography

Diagnostic Performance Characteristics

• The Modified Ashworth Scale assigns a value from 0-4 based on the patient’s muscle tone:
  • 0: Normal tone, with no increase in tone
  • 1: Slight increase in muscle tone, manifested by a catch and release or minimal resistance at the end of the ROM when the affected part(s) is moved in flexion or extension
  • 2: More marked increase in muscle tone through most of the ROM, but affected part(s) easily moved
  • 3: Considerable increase in muscle tone, passive movement difficult
  • 4: Affected part(s) rigid in flexion or extension⁴

• A positive result occurs when the patient displays an increase in muscle tone or rigidity during the assessment.

• A negative result occurs when the patient does not display an increase in muscle tone or rigidity during the assessment.

• Spasticity affects muscles of the upper extremity in characteristic patterns, predominantly the flexor and adductor muscles, resulting in the characteristic flexion-pronation deformity of the upper limb. In addition, spasticity is typically more pronounced in the distal extremity. In the shoulder, adduction and internal rotation predominate, while in the elbow, the biceps, brachialis, and brachioradialis contribute to the flexion deformity. The wrist flexors are the most commonly involved muscles in upper limb spasticity; spasticity of the flexor carpi ulnaris is common and leads to a wrist flexion and ulnar deviation deformity. Hand and finger involvement varies depending on which muscles are predominantly affected but most often appear clenched into a fist. The thumb typically assumes an adducted posture because of increased adductor pollicis activity, but the flexor pollicis longus may also be affected, leading to metacarpophalangeal and interphalangeal joint flexion.⁵

1. Angulo-Parker, FJ and Adkinson, JM. Common Etiologies of Upper Extremity Spasticity. Hand Clin 2018;34(4):437-443. PMID: 30286958
2. Yamaguchi, T, Hvass Petersen, T, Kirk, H, et al. Spasticity in adults with cerebral palsy and multiple sclerosis measured by objective clinically applicable technique. Clin Neurophysiol 2018;129(9):2010-2021. PMID: 30053672
3. Bar-On, L, Molenaers, G, Aertbelien, E, et al. Spasticity and its contribution to hypertonia in cerebral palsy. Biomed Res Int 2015;2015:317047. PMID: 25649546
4. Akpinar, P, Atici, A, Ozkan, FU, et al. Reliability of the Modified Ashworth Scale and Modified Tardieu Scale in patients with spinal cord injuries. Spinal Cord 2017;55(10):944-949. PMID: 28485384
5. Gart, MS and Adkinson, JM. Considerations in the Management of Upper Extremity Spasticity. Hand Clin 2018;34(4):465-471. PMID: 30286961