Page Contents
OVERVIEW
This page is dedicated to organizing various examples of standardized exam questions whose answer is amyotrophic lateral sclerosis (ALS). While this may seem a odd practice, it is useful to see multiple examples of how ALS will be characterized on standardized exams (namely the boards and the shelf exams). This page is not meant to be used as a tradition question bank (as all of the answers will be the same), however seeing the classic “test” characterization for a disease is quite valuable.
KEY CHARACTERISTICS OF THIS CONDITION (ON EXAMS)
When it comes to standardized exams, each topic has its own “code” marked by key buzzwords, lab findings, clues, etc. If you are well versed in this code you will be able to more quickly identify the condition that is being discussed, and get the right answer on the exam you are taking. Below is the “code” for ALS.
Chief Complaints:
- Progressive weakness can occur in the upper and/or lower extremities
- Difficulty swallowing can be caused by muscle weakness
- Respiratory distress is a later stage complication of this condition (caused by muscle weakness)
Clinical Workup: a combination of broth upper and lower motor neuron symptoms helps make this diagnosis.
- Sensory exam will BE NORMAL:
- No sensory deficits will be present in this condition
- Lower motor neuron damage symptoms:
- Fasciculations: very specific for this condition on exams.
- Muscle weakness
- Muscle atrophy
- Upper motor neuron damage symptoms:
- Muscle weakness
- Increased deep tendon reflexes
QUESTION EXAMPLES
Question # 1
A 45 year old woman is brought to the clinic because she has been experiencing weakness in her right hand and left leg. She first noticed these symptoms about 3 months ago. The patient has also noticed occasional twitching of the muscles in both her arms and both of her legs. She believes this is the result of being “very nervous” all of the time. Her past medical history is notable for migraines that are treated with sumatriptan, and her family history is unremarkable. A physical exam reveals atrophy and weakness of both hands. She also demonstrates twitching of her forearm muscles, and has a right footdrop. Her deep tendon reflexes are increased bilaterally, and a Babinkski sign is present on the left. The patients speech is also slurred during the interview. Labs are notable for a creatine kinase that is 340 U/L. Nerve conduction studies demonstrate no abnormalities while EMG studies show acute and chronic denervation of several muscles in all 4 limbs. What is the likely diagnosis?
Explanation # 1
Upper motor neuron signs + lower motor neuron signs + fasciculations = ALS
Question #2
A 58 year old male comes to the clinic because he has been experiencing a 7-month history of widespread muscle cramps. A physical exam is notable for a right foot drop, diffuse muscle atrophy, and there are also fasciculation’s present. Deep tendon reflexes are increased. A sensory exam is unremarkable.
Explanation # 2
Upper motor neuron signs (increased reflexes) + lower motor neuron signs (muscle atrophy) + fasciculations + normal sensory exam = ALS
Question #3
A 48 year old male suffers from progressive weakness of both his hands for the past 8 months. He works as a waiter and has been having trouble service patrons in the restaurant. He has a 50 pack year history of using cigarettes, and drinks 8 alcoholic beverages every week. A neurological exam reveals decreased strength in his upper and lower extremities, and the muscles of his hands are atrophied. Diffuse hyperreflexia is present. Fasciculations are noted by the physician in both his hands and lower extremities. The patient has no sensory deficits present on the examination. What is the likely diagnosis in this patient?
Explanation # 3
Upper motor neuron signs (increased reflexes) + lower motor neuron signs (muscle atrophy) + fasciculations + normal sensory exam = ALS
Question # 4
A 60 year old male comes to the clinic because he has noticed that his muscles have been “wasting away”. He has also noticed weakness that began and progressed in a asymmetric fashion. He notes that he more recently has had difficulty with swallowing, chewing, and even speaking. A physical exam reveals that he has slight movements of the muscles in his face and tongue, and that he has marked atrophy of the muscles in his arms and legs. Hyperreflexia is noted in all of the extremities, however sensory function is preserved within all 4 limbs. What is the likely diangosis in this patient?
Explanation # 4
Upper motor neuron signs (increased reflexes) + lower motor neuron signs (muscle atrophy) + fasciculations + normal sensory exam = ALS
Question # 5
A 55 year old man comes to the clinic because he has noticed progressive weakness in both his arms and legs. About a year ago his routine physical exam showed no abnormalities except for slight weakness in his upper extremities. A current neurological exam reveals moderate weakness in all 4 limbs, and the presence of fasciculations in his hands and his left lower extremity. The patients cranial nerves are grossly intact, and there are no sensory deficits on the exam. An MRI of the brain is performed and is unremarkable.
Explanation # 5
Muscle weakness + fasciculations + normal sensory exam = ALS
Question # 6
A 50 year old male comes to the clinic because he has noticed a 6 month history of weakness that has been worsening. It began in his legs, and soon spread to his arms. He has also noticed difficulty swallowing his food during meals. A neurological exam revel as atrophy of the lower extremities muscles, and fasciculations are present in the quadricep muscles bilaterally. A Babinski sign is also seen bilaterally during the exam. What is the likely diagnosis in this patient?
Explanation # 6
Upper motor neuron signs (Babinski) + lower motor neuron signs (muscle atrophy) + fasciculations = ALS
TESTABLE FACTS ABOUT THIS TOPIC (BEYOND ITS IDENTIFICATION)
Many questions on standardized exams go beyond simply recognizing the underlying topic. Often there are specific testable facts regarding some aspect of the topic’s pathophysiology/management/clinical implications that are commonly asked. Some of these are listed below:
Cause: this condition is fundamentally caused by motor neuron degeneration.
- Damage to anterior horn cells: manifests as lower motor neuron injury
- Demyelination of corticospinal tracts: manifests as upper motor neuron injury
Making The Diagnosis:
- Fibrillation potentials will be present on EMG (very characteristic to ALS).
- Motor neuron damage can be appreciated histologically such as the degeneration of anterior horn cells in the spinal cord and demyelination of the corticospinal tracts discussed above.
Page Updated: 01.21.2017