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[Dr. Shapiro] This is Dr. Samantha Shapiro, executive editor of Harrison's Principles of Internal Medicine. Harrison's Podclass is brought to you by McGraw Hill's AccessMedicine, the online medical resource that delivers the latest trusted content from the best minds in medicine. And now, onto the episode.
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[Dr. Handy] Hi, everyone. Welcome back to Harrison's Podclass. We're your co-hosts, I'm Dr. Cathy Handy.
[Dr. Wiener] And I'm Dr. Charlie Wiener and we're joining you from the Johns Hopkins School of Medicine.
[Dr. Handy] Welcome to episode 97, a 74-year-old with thigh pain.
[Dr. Wiener] Hey, Cathy. So, today's patient is a 74-year-old man who presents with severe pain in his right thigh. This pain came on suddenly about a few weeks ago and he also notes some weakness in the right leg when he is trying to climb the stairs. He has a past medical history significant for hypertension, hyperlipidemia, and type two diabetes, and his most recent hemoglobin A1C was 10%. On physical examination, he has weakness in his right hip flexors, which are about 4 to 5 on strength testing as opposed to 5 over 5 on the left side, but he has preserved strength everywhere else. Proprioception and pin prick sensation are preserved distally in both lower extremities and all the way down to the toes. However, there is no decreased sensation of the thigh on the right side. So Cathy, based on that, what are your thoughts so far?
[Dr. Handy] It sounds like he has pain that's limited to one nerve root and this is associated with motor weakness of the same area. Given that combination of symptoms and signs, imaging of the spine would be reasonable because it localizes to a specific lesion in the spine.
[Dr. Wiener] Okay, so you're saying that because he has both sensory and motor sensation problems, we should get an MRI, and that is done. So an MRI of the lower spine without contrast is unremarkable. There are no abnormalities seen. So now, the question's going to ask, which of the following is the most likely cause of his symptoms? And the options are A. diabetic amyotrophy; B. distal symmetric polyneuropathy from diabetes; C. herniation of a lumbar disc; D. meralgia paresthetica; or E. vertebral compression fracture.
[Dr. Handy] All right. Well, there are some answer choices that we can eliminate right away. So C. herniation of the lumbar disc, and E. vertebral compression fracture can both be eliminated. Those can both cause a radiculopathy, but they would both show up on imaging and we heard in this case that imaging was negative. We can also eliminate D. because meralgia paresthetica caused by compression of the lateral femoral cutaneous nerve would only involve sensory changes and it wouldn't cause a motor weakness.
[Dr. Wiener] Okay. So that leaves us with either A. or B. as the correct answer, right?
[Dr. Handy] Yeah, and what stands out from this person's history is the hemoglobin A1C of 10% which is well above the goal, and that along with the absence of any imaging findings. So diabetic amyotrophy is a syndrome characterized by severe disabling pain in the distribution of one or more nerve roots, and it may also be accompanied by motor weakness, which this patient has. So for this question, I would choose option A.
[Dr. Wiener] So what about option B? Tell me about that.
[Dr. Handy] So distal symmetric polyneuropathy is the most common form of diabetic neuropathy, and that most frequently presents with distal sensory loss and pain, but up to 50% of patients don't have symptoms of neuropathy. The symptoms may include a sensation of numbness, tingling, sharpness, or burning, and it usually begins in the feet and spreads proximally, but this wasn't described in this patient.
[Dr. Wiener] Okay, so this patient seems to have a complication of diabetes. Let's talk a little bit more about that.
[Dr. Handy] Yeah, diabetes-related complications can affect many organ systems and are responsible for the majority of morbidity and mortality associated with the disease. For many years in the United States, diabetes has been the leading cause of new blindness in adults, renal failure, and non-traumatic lower extremity amputation. More recently, diabetes has also emerged as a leading contributor to coronary heart disease. Diabetes-associated complications related to hyperglycemia usually do not appear until the second decade of hyperglycemia. In contrast, diabetes-associated coronary heart disease risk related in part to insulin resistance may develop before hyperglycemia is established. Because type two diabetes mellitus often has a long asymptomatic period of hyperglycemia before diagnosis, many individuals with type two diabetes have both glucose-related and insulin resistance-related complications at the time of diagnosis.
[Dr. Wiener] So is this complication we're describing today and some of the other neurologic complications, are they related to the degree of chronic hyperglycemia?
[Dr. Handy] Yes, they are as evidenced by the A1C which is a measure of the longer term glucose control.
[Dr. Wiener] And what are the mechanisms of these complications in diabetes?
[Dr. Handy] Well, diabetes-related complications can be divided into vascular and non-vascular complications, and they're similar for type one and type two diabetes. Now, although hyperglycemia serves as the initial trigger for complications of diabetes, it's still unknown whether the same pathophysiologic processes are operative in all complications, or whether some of the pathways predominate in certain organs, but many of the complications are likely multifactorial.
[Dr. Wiener] Okay, great. So the teaching point of this case is that diabetic amyotrophy is a complication of chronic hyperglycemia and diabetes. It typically presents with focal pain and focal motor weakness.
[Dr. Handy] And you can learn more about this on the chapter on diabetes mellitus and complications.
[Dr. Shapiro] Thanks for listening to Harrison's Podclass. You can listen to this episode and more on AccessMedicine.com, which includes the complete Harrison's Principles of Internal Medicine text, Harrison's review questions which compliment and expand upon the the questions in this episode, and much more. AccessMedicine.com may already be available to you via your academic institution. Check it out.
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