Neuromuscular Junction Disorders Quiz

During a biology class, Evelyn was asked to identify the chemical synapse that lies between the terminal ends of motor neurons and skeletal muscle fibers. What is her correct answer?

• Schwann cell junction

• Neuromuscular receptor

• Synaptic cleft

• Myoneural junction

Answer explanation

The correct answer is the 'Synaptic cleft' which is the chemical synapse between motor neurons and skeletal muscle fibers.

Which receptor is thought to act in muscle fibers for postsynaptic differentiation?

• LRP4

• MuSK

• VGCC

• AChR

Answer explanation

MuSK is thought to act in muscle fibers for postsynaptic differentiation, making it the correct choice.

Which disorder is the most common neuromuscular junction disorder?

• Amyotrophic Lateral Sclerosis

• Multiple Sclerosis

• Myasthenia Gravis

• Lambert-Eaton Myasthenic syndrome

Answer explanation

Myasthenia Gravis is the most common neuromuscular junction disorder, characterized by muscle weakness and fatigue. It is caused by antibodies attacking acetylcholine receptors.

What is the major symptom of Lambert-Eaton Myasthenic syndrome?

• Oculobulbar symptoms

• Muscle tenderness

• Generalized fatigable weakness

• Respiratory muscle weakness

Answer explanation

The major symptom of Lambert-Eaton Myasthenic syndrome is generalized fatigable weakness.

Which antibody is most commonly targeted in Myasthenia Gravis?

• Anti-LRP4

• Anti-MuSK

• Anti-AChR

• Anti-VGCC

Answer explanation

In Myasthenia Gravis, the most commonly targeted antibody is Anti-AChR, which plays a crucial role in the pathophysiology of the disease.

What is the first-line immunosuppressive therapy for a patient with Myasthenia Gravis?

• Azathioprine

• Plasmapheresis

• Intravenous immunoglobulin

• Corticosteroids

Answer explanation

Corticosteroids are the first-line immunosuppressive therapy for MG, helping to reduce inflammation and improve muscle strength.

Which diagnostic test is most sensitive for detecting muscle weakness in Evelyn?

• Edrophonium test

• Serologic testing

• Repetitive nerve stimulation

• Ice pack test

Answer explanation

Repetitive nerve stimulation is the most sensitive diagnostic test for MG, as it can detect abnormalities in neuromuscular transmission even in the absence of clinical weakness.

What is the characteristic finding in EMG for Lambert-Eaton Myasthenic syndrome?

• Jitter response

• Incremental response

• Decremental response

• Normal response

Answer explanation

The characteristic finding in EMG for Lambert-Eaton Myasthenic syndrome is an Incremental response.

What is the most serious and first symptom to treat in a patient with Myasthenia Gravis?

• Facial weakness

• Upper limbs weakness

• Weakness of diaphragmatic and intercostal muscles

• Diplopia

Answer explanation

The most serious and first symptom to treat in a patient with MG is weakness of diaphragmatic and intercostal muscles, as it can lead to respiratory compromise and is life-threatening.

Which medication is known to significantly improve muscle strength and autonomic symptoms in approximately 80% of patients with Lambert-Eaton myasthenic syndrome (LEMS)?

• Cyclophosphamide

• 3,4-Diaminopyridine

• Mycophenolate mofetil

• Azathioprine

Answer explanation

3,4-Diaminopyridine is the medication that improves muscle strength and autonomic symptoms in approximately 80% of patients with LEMS.