AANP Family Nurse Practitioner (FNP) Certification ExamDiagnosisHard
A 55-year-old male presents with a 3-month history of progressive muscle weakness, particularly in his hands and arms. He reports difficulty with fine motor tasks like buttoning shirts and writing. He also notes muscle twitching (fasciculations) and occasional muscle cramps. On examination, he has atrophy of intrinsic hand muscles and hyperreflexia in his lower extremities. Sensory examination is normal. What is the most likely diagnosis?
- AMultiple Sclerosis
- BGuillain-Barré Syndrome
- CAmyotrophic Lateral Sclerosis (ALS)
- DMyasthenia Gravis
Show answer & explanationAnswer & explanation
Correct answer: C. Amyotrophic Lateral Sclerosis (ALS)
The clinical picture of progressive upper and lower motor neuron signs (weakness, atrophy, fasciculations, cramps, hyperreflexia) without sensory involvement is highly characteristic of Amyotrophic Lateral Sclerosis (ALS). The onset in hands and arms is common.
Why the other options are wrong
- A. Multiple Sclerosis is a demyelinating disease presenting with a variety of neurological symptoms (sensory, motor, visual, cerebellar) that are often relapsing-remitting, and typically includes sensory deficits.
- B. Guillain-Barré Syndrome is an acute, rapidly progressive demyelinating polyneuropathy causing ascending paralysis and areflexia, often preceded by an infection, which is inconsistent with this chronic, progressive presentation with hyperreflexia.
- D. Myasthenia Gravis causes fluctuating muscle weakness, often worse with activity, and typically affects ocular and bulbar muscles first, without fasciculations or hyperreflexia.
Amyotrophic Lateral Sclerosis (ALS)
ALS is a progressive neurodegenerative disease affecting motor neurons in the brain and spinal cord, leading to muscle weakness, atrophy, fasciculations, and spasticity, without sensory involvement.
- Involves both upper motor neuron (UMN) and lower motor neuron (LMN) signs.
- UMN signs: spasticity, hyperreflexia, pathological reflexes (Babinski).
- LMN signs: weakness, atrophy, fasciculations, cramps.
- Sensation and cognitive function are typically preserved.
Memory trick: ALS: All Limbs Slowly weaken, but Sensation stays.