Clinical Aspects of Upper Limb Paralysis

1. Terminology and Grading

• Plegia = complete paralysis; paresis = partial weakness. In clinical practice, "paralysis" is often used for both.
• Patterns affecting the upper limb include:
  • Monoplegia - single upper limb
  • Hemiplegia - ipsilateral arm + leg (one body side)
  • Brachial diplegia - both upper extremities
  • Quadriplegia/tetraplegia - all four limbs

• Localization in Clinical Neurology, 8e

2. Localizing the Lesion: UMN vs. LMN

Important exception: In acute UMN lesions (e.g., acute stroke, spinal shock), tone and reflexes are initially decreased (flaccid paralysis) and only become spastic over hours to months.

• Neuroanatomy through Clinical Cases, 3rd ed.; Ganong's Review of Medical Physiology, 26th ed.

3. Upper Motor Neuron (UMN) Paralysis

Anatomy of the pathway

Sites of UMN lesions causing upper limb involvement

Clinical features of UMN upper limb weakness

• Spasticity - velocity-dependent increase in tone; "clasp-knife" character on passive stretch
• Antigravity muscle pattern - in the upper limb, spasticity predominates in flexors (shoulder adductors, elbow flexors, wrist/finger flexors): the arm is adducted at the shoulder, flexed at elbow, wrist pronated and fingers flexed
• Weakness distribution - most marked in deltoid, triceps, wrist extensors, and finger extensors (the "extensors and supinators")
• Hyperreflexia - exaggerated deep tendon reflexes
• Pathological reflexes:
  • Hoffmann's sign (upper limb equivalent of Babinski): flicking the middle fingernail causes thumb and index finger flexion - positive in UMN lesions
  • Babinski sign in the lower limb confirms UMN pathology
• Clonus - rhythmic oscillation on sudden stretch
• No atrophy, no fasciculations

Causes

• Localization in Clinical Neurology, 8e

4. Lower Motor Neuron (LMN) Paralysis

4a. Anterior Horn Cell / Spinal Cord

• Poliomyelitis, ALS (motor neuron disease), spinal muscular atrophy
• Flaccid, wasted, fasciculating muscles; areflexia

4b. Nerve Root Lesions (Radiculopathy)

4c. Brachial Plexus Lesions

• Most common brachial plexus palsy (~20x more frequent than Klumpke's)
• Mechanism: forced depression of the shoulder (birth traction, motorcycle fall widening the neck-shoulder angle)
• Clinical: "waiter's tip" posture - adduction and internal rotation of the shoulder, extension of the elbow, pronation of forearm, wrist flexed
• Muscles affected: deltoid, biceps, brachioradialis, supraspinatus, infraspinatus
• Biceps reflex absent; sensation lost over lateral arm/forearm
• Prognosis: >90% resolve by 3 months in neonatal cases; biceps function is the key prognostic indicator

• Rare
• Mechanism: forced hyperabduction/extension of the arm over the head
• Clinical: claw hand - weakness/paralysis of intrinsic hand muscles (interossei, lumbricals, hypothenar and thenar muscles), finger/wrist flexors
• May include Horner's syndrome (ptosis, miosis, anhidrosis) if T1 root involved (sympathetic fibers)
• Sensory loss on ulnar side of hand and medial forearm

• Rare; entire upper limb flaccidly paralyzed
• Causes: high-velocity trauma (motorcycle accidents)

• Lower trunk compression at the thoracic outlet
• Weakness of intrinsic hand muscles (both median and ulnar distributions); sensory loss mainly ulnar
• Often caused by cervical rib or fibrous band
• Miller's Review of Orthopaedics, 9th ed.; Bradley and Daroff's Neurology in Clinical Practice; Adams and Victor's Principles of Neurology, 12th ed.

4d. Peripheral Nerve Lesions

5. Special Patterns

Spastic Hemiparesis (Stroke/UMN)

• Upper limb posture: shoulder adducted, elbow flexed, wrist pronated, fingers flexed
• Lower limb: extended (spastic), circumduction gait
• Hoffmann's sign positive; hyperreflexia

Spinal Cord Lesions

• Complete cervical cord (above C5): quadriplegia
• C5-C6 cord injury: LMN signs at the level (flaccid arms), UMN signs below (spastic legs)
• Brown-Sequard syndrome: ipsilateral UMN weakness + loss of proprioception; contralateral pain/temperature loss

Neuralgic Amyotrophy (Parsonage-Turner Syndrome)

• Non-traumatic, often triggered by surgery, infection, or illness
• Sudden severe shoulder pain followed by flaccid paralysis of upper limb muscles
• Brachial plexus distribution; usually unilateral
• Good prognosis but recovery can take months to years
• Rockwood and Green's Fractures in Adults, 10th ed.

6. Clinical Approach Summary

1. History - onset (sudden = vascular; progressive = neoplasm/MND; episodic = MS), pain (suggests nerve/root), trauma
2. Examination - tone, power (MRC), reflexes, sensation, Hoffmann's sign, atrophy, fasciculations
3. Localize - UMN vs. LMN; level (cortex → cord → root → plexus → nerve)
4. Investigations:
   • MRI brain/spine (UMN, cord, root)
   • EMG/NCS - confirms LMN level; distinguishes root vs. plexus vs. nerve
   • Plain X-rays/CT (fractures, cervical ribs)
   • Blood tests (if systemic cause suspected)

• Localization in Clinical Neurology, 8e - MRC scale, UMN/LMN localization
• Neuroanatomy through Clinical Cases, 3rd ed. - UMN vs. LMN table
• Bradley and Daroff's Neurology in Clinical Practice - Brachial plexus trauma
• Miller's Review of Orthopaedics, 9th ed. - Erb's and Klumpke's palsy
• Adams and Victor's Principles of Neurology, 12th ed. - Flaccid paralyses
• Ganong's Review of Medical Physiology, 26th ed. - UMN vs. LMN signs