This page is dedicated to organizing various examples of standardized exam questions whose answer is subacute combined degeneration. While this may seem a odd practice, it is useful to see multiple examples of how subacute combined degeneration will be characterized on standardized exams (namely the boards and the shelf exams). This page is not meant to be used as a traditional 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 subacute combined degeneration.
- Decreased proprioception: this can present in numerous ways
- Worse gait in the dark
- Positive Romberg test (on exam)
- Signs of upper motor neuron damage: can include such things as…
- Babinski sign
- Increased reflexes
- Increased serum homocysteine and methylmalonic acid levels these will rise before serum B12 is decreased. Both are increased (unlike folate deficiency that only has increased homocysteine).
Question # 1
Over the past 7 months a 62 year old male has become confused when following directions, has had paresthesias of the hands/feet, and also has an unsteady gait that worsens in the dark. His past medical history is notable for atrophic gastritis. A physical exam shows hyperreflexia of the lower extremities, and the Babinkski signs is present bilaterally. His sensation to vibration is significantly decreased over the hands and the feet. Mental status testing that he cannot recall three objects after 5 minutes. What is a possible diagnosis?
Explanation # 1
Impaired proprioception + upper motor neuron issues (increased reflexes/Babinski sign) = subacute combined degeneration (likely due to issues absorbing vitamin B12 secondary to atrophic gastritis)
Question # 2
Explanation # 2
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:
Page Updated: 03.28.2017