Diabetic amyotrophy

Discussion

Diabetic amyotrophy is also known as diabetic lumbosacral plexopathy, Bruns-Garland syndrome, diabetic myelopathy, and diabetic lumbosacral radiculoplexus neuropathy.² It is important for clinicians to be aware of the distinctive course of diabetic amyotrophy, which consists of severe neuropathic pain, motor weakness, proximal muscle atrophy, and weight loss (typically exceeding 10 lbs). The disease progressively worsens until eventual stabilization, which is followed by gradual recovery, often with some residual impairment.³ Better recognition of this disorder is likely to result in more rapid diagnosis, appropriate counselling, and proper subspecialty referral.⁴

The literature search was conducted using MeSH terms diabetic amyotrophy, diabetic lumbosacral radiculoplexus neuropathy, and Bruns-Garland syndrome on PubMed and Google Scholar. The search was restricted to articles published between 1996 and 2022.

Incidence. Diabetic amyotrophy occurs in approximately 0.8% of all patients with diabetes⁵ and affects males more frequently than females.⁶ This syndrome affects an older diabetic group, usually older than 50 years, with the median age of onset older than 65 years.³ It may occur as a complication of a prediabetic state or may result from tighter glycemic control in patients with newly diagnosed diabetes.⁷ Multiple case studies have shown that acute lowering of blood glucose or tighter diabetes control in a patient with chronic hyperglycemia may act as a possible trigger for diabetic amyotrophy.⁸ It is unclear if this was a precipitant in our patient.

Pathophysiology. Pathophysiology of this condition is still debatable and has not yet been elucidated. Based on current evidence, this condition appears to be an immune-mediated, inflammatory microvasculitis causing ischemic damage of the nerves of the lumbar plexus. There is some speculation that metabolic injury from hyperglycemia also contributes to the disease process.⁹

Diagnosis. Diabetic amyotrophy is a clinical diagnosis consistent with our patient’s history and physical examination findings. Electromyography and nerve conduction studies carry importance in firmly establishing diagnosis. Magnetic resonance imaging of the lumbar spine and the lumbosacral plexus can help rule out space-occupying lesions that may be compressing the plexus and causing similar symptoms.¹⁰

Management. The treatment of diabetic amyotrophy remains supportive. This includes maintaining adequate diabetes control, pharmacotherapy for neuropathic pain, physiotherapy, and assistive devices or braces.⁶ Although diabetic amyotrophy is suspected to be secondary to microvasculitis, there is currently no evidence to support the use of intravenous immunoglobulin or any long-term immunosuppression or corticosteroid use.⁷

Prognosis. While diabetic amyotrophy can be acutely disabling at diagnosis, the prognosis for recovery is favourable. Generally, symptoms are severe for the first 6 months and gradually decrease, with resolution usually occurring within 1 to 3 years.¹¹ Multiple studies have demonstrated eventual pain relief and a near return to a patient’s functional baseline.⁴ Our patient’s symptoms of pain and weakness initially worsened over the course of 2 to 3 weeks. His pain was managed with pregabalin, and a scheduled dosage of hydromorphone with breakthrough hydromorphone as needed. He initially used a wheelchair but slowly improved with supportive management and regained the ability to walk with gait aids. Given that our patient had other complicating factors (eg, concerns related to social determinants of health, need for ongoing hemodialysis), he was subsequently discharged to a long-term care facility.