Motor Neuron Disease

Clinic

MNDs are a group of rare neuro-degenerative disorders that selectively affect motor neurons, including

• Amyotrophic lateral sclerosis (ALS)
• Progressive bulbar palsy (PBP)
• Pseudobulbar palsy
• Progressive muscular atrophy (PMA)
• Primary lateral sclerosis (PLS)
• Spinal muscular atrophy (SMA) (Gentic)
• Monomelic amyotrophy (MMA)

Signs / Symptoms

UMN

• Spasticity, Increased muscle tone
• Overactive reflexes: Hyper reflexia or Abnormal reflexes (Brisk reflexes, Babinski reflex, Hoffman's reflex)
• Slow / Difficult. voluntary movements
• Inability to walk or control other movements.

LMN

• Muscle Wasting / Weakness / Atrophy
• Muscle Twitching/ Fasciculations

• Hypotonia or atonia
• Hypo reflexia

Bulbar

• Dysarthria
• Dysphagia
• Sialorrhea

• Pseudobulbar affect

• Cognitive / Behavioural changes (Problems in word fluency, Decision-making, and Memory)
• Sensation (Ability to feel) is typically not affected

Common symptoms

• Gait abnormalities
• Tongue atrophy
• Upper limb and truncal muscle atrophy
• Positive Babinski sign
• Thenar muscle atrophy

• Exertion Dyspnea
• Orthopnea

Various Patterns of weakness

• Symmetric or asymmetric
• Distal, proximal, or both

• According to Statland et al., there are three main weakness patterns:

1. Asymmetric distal weakness without sensory loss (e.g. ALS, PLS, PMA, MMA)
2. Symmetric weakness without sensory loss (e.g. PMA, PLS)
3. Symmetric focal midline proximal weakness (neck, trunk, bulbar involvement; e.g. ALS, PBP, PLS)

Classification

Type	UMN degeneration	LMN degeneration
Sporadic MNDs
ALS	Yes	Yes
PLS	Yes	No
PMA	No	Yes
PBP	Yes	Yes, bulbar region
Pseudobulbar palsy	Yes, bulbar region	No
MMA	No	Yes

Entities / Miasms

Miasms	UMN	LMN	Emotional lability	Bulbar palsy
CJD	+++	+++
PLV	+	+++		+++
GSS	+++		+++
TBE		+++	+++
NVCJD ?	+++			+++ ???