UMNL Upper Motor Neuro Lesion

Question 1

What is it

Answer 1

A lesion affecting the upper motor neurons (UMNs) in the cerebral cortex, brainstem, or spinal cord, leading to loss of voluntary movement control but increased muscle tone and reflexes.

Question 2

Clinical Features

Answer 2

🔹 Key Signs of UMN Lesion:

Muscle weakness (paresis) WITHOUT atrophy (initially) 💪❌
Spasticity (increased muscle tone) 💥💪
Hyperreflexia (exaggerated deep tendon reflexes) 🦵⚡
Clonus (involuntary, rhythmic muscle contractions) 🌀
Babinski sign (toes extend upward with foot stimulation) 🦶⬆️
No fasciculations (unlike LMN lesions)

Question 3

Epidemiology

Answer 3

Common in stroke, spinal cord injury, multiple sclerosis, and cerebral palsy
Can occur at any age but more common in older adults due to stroke & neurodegenerative diseases

Question 4

Age Groups Affected

Answer 4

Any age: Trauma, congenital disorders (cerebral palsy)
Young adults: Multiple sclerosis (MS) - 20 - 40
Middle-aged to older adults: Stroke - 50+
neurodegenerative diseases

Question 5

Risk Factors

Answer 5

✅ Modifiable:
Hypertension & atherosclerosis (stroke risk) 🩸
Smoking & diabetes (vascular damage) 🚬
Head or spinal cord trauma (accidents, falls, sports injuries)
Vitamin B12 deficiency (can affect spinal cord UMNs)

🚫 Non-Modifiable:
Congenital conditions (cerebral palsy, hereditary spastic paraplegia)
Neurodegenerative diseases (ALS, MS, Parkinson’s disease)
Spinal cord or brain tumors

Question 6

Clinical Presentation

Answer 6

🔹 If Cortex/Brainstem Lesion (e.g., Stroke, MS):
weakness/paralysis on one side of the body
Facial weakness (lower face affected, forehead spared – unlike LMN lesion)
Spasticity & hyperreflexia in affected limbs
Babinski sign (toes extend up)

🔹 If Spinal Cord Lesion (e.g., Trauma, MS):
Paraplegia (both legs affected) or quadriplegia (all limbs affected) if severe
Hyperreflexia & spasticity below the lesion level
Loss of voluntary motor control

🔹 If Progressive Neurodegenerative Disease (e.g., ALS, MS):
Gradual worsening of spasticity & weakness
Speech & swallowing difficulties (if brainstem involved)

Question 7

Prognosis

Answer 7

🔹 Depends on the cause:
Stroke-related: Can improve with rehab, but deficits may persist
Spinal cord injury: Permanent damage likely if severe
Multiple sclerosis: Relapsing-remitting or progressive decline
Cerebral palsy: Lifelong motor impairment, but therapy helps
ALS (both UMN & LMN affected): Progressive & fatal

🔹 Treatment & Management:
Physical therapy & rehabilitation 🏋️‍♂️
Medications (e.g., baclofen for spasticity) 💊
Stroke prevention (control BP, diabetes, lifestyle changes)

Question 8

Tests

Answer 8

1. Muscle tone test (“fast PROM”) - checking for spasticity
   There will be increased resistance to the movement
   “Clasp-knife response” initial resistance then sudden relaxation
2. Deep tendon reflex
3. Babinski sign (plantar reflex)
4. Clonus - uncontrolled reflex activity
5. Hoffman’s test