Neuromuscular Disease

Question 1

How are the motor and sensory neurons arranged in the PNS?

How does the spinal nerve split?

What is a Lower Motor Neuron (LMN)?

What is an Upper Motor Neuron (UMN)?

What does it mean for a nerve fibre to decussate?

Answer 1

• • Motor neuron is ANTERIOR (motor root)
  • DORSAL SENSORY root joins with motor root to form a short spinal nerve after the dorsal root ganglion
• Splits into a dorsal ramus and ventral ramus
• Motor nerve from anterior horn to muscle
• Part of the CNS; starts in Primary Motor Cortex (Pre-central gyrus), travels down into the pyramids of the medulla, where it decussates
• Crosses over to opposite side

Question 2

Mononeuropathies:
What is Carpal Tunnel Syndrome?

What is Cubital Tunnel Syndrome?

What is Radial Neuropathy? What can cause it?

What is Peroneal Neuropathy?

Answer 2

• Compression of MEDIAN NERVE, which runs directly under the Transverse Carpal Ligament
• Ulnar Neuropathy; Compression of ULNAR NERVE in the cubital tunnel
• Compressed of Radial nerve at spiral groove of humerus; caused by prolonged compression or humeral fracture
• FOOT DROP; weakness of ankle dorsiflexion and eversion

Question 3

Polyneuropathies (Peripheral Neuropathy):
What does it present as? Why?

How does the sensory loss progress?

What is Guillain-Barre Syndrome? What does it lead to?

What other symptoms are present with this syndrome?

How is this syndrome treated?

Answer 3

• “GLOVE AND STOCKING” distribution of sensory loss; Longest nerves affected first
• Starts in toes and extends proximally to just below the knee, then it affects the hands; when very advanced, can cause midline sensory loss
• Acute, inflammatory neuropathy; leads to ascending sensory and motor paralysis due to demyelination/axonal damage
• Respiratory paralysis within 48 hours, Paresthesia, Pain, Cranial neuropathies, Diarrhoea/Constipation
• IV IgG therapy, Plasmapheresis

Question 4

Multiple Mononeuropathies (Mononeuritis Multiplex):
What is it's distribution like? Why?

What commonly causes it?

Anterior Horn Cell Disorders (Motor Neuron Disease):
What is the most common form of MND? What is it? What does it affect?

What are the symptoms?

Answer 4

• Asymmetric distribution; different nerves affected in all limbs
• Vasculitis, Diabetes

• Amyotrophic Lateral Sclerosis (ALS); degeneration of LMNs and UMNs
  o Affects Bulbar, Upper and Lower limbs
• Muscle wasting, Weakness, Fasciculations, Hyperreflexia

Question 5

Radiculopathy:
What’s the distribution like? Why?

What commonly causes it?

Myasthenia Gravis:
What does it produce?

What are the symptoms?

Myopathy:
What is the main sign of it?

What is Duchenne and Becker Muscular Dystrophy?

Answer 5

• Dermatomal distribution; Nerve ROOTS affected
• Arthritic vertebra, Intervertebral disc herniation

• Autoantibodies to ACh receptors
• Weakness, Blurred vision, Ptosis, Double vision, Problems swallowing, Slurred speech, Fatigue

• Proximal weakness
• Weakness from birth, Difficulty standing, Abnormal posture, Calf hypertrophy