PrepTest 154, Section 2, Question 19
Doctor: The patient had been experiencing back and(84 more words not shown)
Which one of the following(8 more words not shown)
- AComputerized scans are(10 more words not shown)
- BThe cortisone injection(12 more words not shown)
- CThe pain relief(14 more words not shown)
- DOnly cortisone injections(16 more words not shown)
- EThe best treatment(12 more words not shown)
Reading the argument
The scan suggests a possible explanation for the pain. Pressure on the nerve can cause inflammation, and inflammation can cause pain. Then an injection intended to reduce inflammation brings relief. I can see why the doctor connects those facts.
But does successful treatment establish the original cause?
Imagine pain arising from some other problem, such as a tumor, and a treatment relieving that pain without identifying what produced it. If that happened, feeling better wouldn't show that pressure on this nerve was the cause. That's a hypothetical way symptom relief could come apart from diagnosis, not a claim about what cortisone does to tumors or nerves.
What we’re looking for
The doctor moves from “the injection helped” to “the suspected pressure caused the pain.” For the required assumption, I'd look for something excluding an alternative explanation of why the pain went away. My initial thought is that the treatment couldn't simply relieve pain that came from another source. Let's see which alternative the answers address.
Working the answers
- A
The scan doesn't have to be the most accurate diagnostic method. Another method could be more accurate, and this scan could still provide useful information. The doctor's final inference also relies on the response to treatment, not on a claim that no better diagnostic technique exists.
- B
Pressure and inflammation are different parts of the proposed chain. The doctor says the injection was meant to reduce inflammation; the conclusion attributes the pain to pressure on the nerve. The argument doesn't require that the injection left the pressure unchanged. It could also have reduced pressure without ruining the doctor's explanation. B adds a restriction the reasoning doesn't need.
- CCorrect
This identifies a different alternative from the one I initially imagined: relief due merely to the patient's belief that the injection would help. If belief alone explains the improvement, the improvement doesn't show that the injection reduced inflammation caused by pressure on the nerve.
For the treatment response to support this diagnosis, the doctor needs to exclude that pure belief-based explanation. Notice the limit: C doesn't say the patient's expectations played no role at all. It says they weren't the whole explanation. That is enough to preserve the response as potential evidence about the physical cause.
- D
Other treatments could also reduce this kind of inflammation. The doctor's account doesn't require cortisone to be the only effective option; it uses the result of the treatment actually given to infer what caused this patient's pain. Exclusivity isn't needed for that reasoning.
- E
The conclusion concerns the cause of this patient's pain, not the best treatment for back and leg pain generally. Other cases might have different causes and call for different treatments. The doctor doesn't need a rule about what usually works best to make this particular diagnosis.
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