MKSAP quiz: Type 2 diabetes and difficulty walking
This month's quiz asks readers to evaluate a 63-year-old man with type 2 diabetes and low back pain, intense pain of the left anterior thigh, buckling of the left knee, paresthesias of the feet, difficulty walking, and weight loss.
A 63-year-old man is evaluated for a 2-week history of low back pain, intense pain of the left anterior thigh, buckling of the left knee, paresthesias of the feet, difficulty walking, and a 6.8-kg (15-lb) weight loss. Six weeks ago, he developed a severe flulike illness. He has a 2-year history of well-controlled type 2 diabetes mellitus. His medications are metformin and ibuprofen.
On physical examination, vital signs are normal. He has an antalgic gait. Atrophy of the left anterior thigh muscles is noted. Muscle strength testing shows weakness of left hip flexors (3/5) and of left knee extensors (3/5). The patellar stretch reflex is absent on the left and normal on the right. Achilles reflexes are normal bilaterally. Sensory examination shows decreased sensation to light touch and pinprick over the left anteromedial thigh but normal findings in the legs and feet bilaterally.
Laboratory testing shows a hemoglobin A1c value of 6.5%.
Which of the following is the most likely diagnosis?
A. Diabetic amyotrophy
B. Diabetic polyneuropathy
C. Guillain-Barré syndrome
D. Meralgia paresthetica
MKSAP Answer and Critique
The correct answer is A. Diabetic amyotrophy. This item is available to MKSAP 18 subscribers as item 5 of extension set 3 in the Neurology section. More information about MKSAP 19, which will be released Aug. 31, is available online.
This patient's symptoms and clinical findings are typical of diabetic amyotrophy, a lumbar polyradiculopathy affecting primarily muscles of the thigh (L2 through L4 spinal levels). Diabetic amyotrophy, which can follow a period of significant weight loss in persons with diabetes mellitus, classically presents with the acute, asymmetric, focal onset of pain followed by weakness involving the proximal leg, with about half of patients developing autonomic symptoms (such as orthostatic hypotension, tachycardia, constipation, diarrhea, and urinary and sexual dysfunction). Progression occurs over weeks to months, sometimes with spread to the contralateral lower extremity or upper extremities. The disorder can occur in well-controlled and even undiagnosed diabetes.
Diabetic polyneuropathy is a length-dependent dying-back axonopathy presenting with distal to proximal sensory loss, paresthesias, pain, and distal lower extremity weakness. Clinical examination typically reveals absent or significantly decreased Achilles reflexes, a gradient stocking distribution of sensory loss, and weakness of the distal lower extremity muscles. The patient's anterior thigh pain and normal distal extremity sensation argue against this diagnosis.
Although Guillain-Barré syndrome (GBS) can present with significant low back pain, this patient's severe thigh pain would be very unusual in GBS. Numbness and, frequently, weakness in GBS are typically symmetric and spread distal to proximal. Deep tendon reflexes would be diffusely hypoactive or absent in both legs.
Meralgia paresthetica causes only sensory loss with mild to moderate dysesthesia over the lateral thigh, without any associated lower extremity weakness.
Key Point
- Diabetic amyotrophy is a lumbar polyradiculopathy affecting primarily muscles of the thigh (L2 through L4 spinal levels) that classically presents with severe pain at onset followed by development of weakness and numbness over weeks to months.