Practice Essentials
Proximal neuropathy in diabetes mellitus (DM) is a condition in which patients develop severe aching or burning and lancinating pain in the hip and thigh. This is followed by weakness and wasting of the thigh muscles, which often occur asymmetrically. This disabling condition occurs in type 1 and type 2 DM. Bruns first described the disorder in patients with DM in 1890. [1] In 1955, Garland coined the term diabetic amyotrophy, although the name Bruns-Garland syndrome is also used to describe the condition. [2, 3, 4, 5, 6]
Diabetic amyotrophy, which is distinct from other types of diabetic neuropathy, usually has its onset during or after middle age (although it can occur in younger individuals). Concomitant distal, predominantly sensory neuropathy may exist. The results of most electrodiagnostic studies are consistent with the presence of a neurogenic lesion that could be associated with lumbosacral plexopathy, radiculopathy, or proximal crural neuropathy. [7, 8, 9, 10] However, the exact cause of diabetic lumbosacral plexopathy is not known. [11]
If, as often occurs, the pathology of lumbosacral plexopathy involves not only the plexus but also the root and nerve levels, the disorder is called lumbosacral radiculoplexus neuropathy. [12]
For more information, see Type 1 Diabetes Mellitus, Type 2 Diabetes Mellitus, Diabetic Neuropathy, and Electrophysiology.
Signs and symptoms of diabetic lumbosacral plexopathy
Several findings commonly are reported in patients with diabetic lumbosacral plexopathy. These include asymmetrical pain in the hip, buttock, or thigh and proximal weakness in the quadriceps, hip adductors, and iliopsoas muscles.
Workup in diabetic lumbosacral plexopathy
In evaluating suspected diabetic lumbosacral plexopathy, neural and electrophysiologic studies are generally helpful. Laboratory tests used to diagnose or assess control of diabetes mellitus (eg, fasting blood glucose, hemoglobin A1C) should be performed.
In addition, lumbar puncture results may show elevated cerebrospinal fluid (CSF) proteins, sometimes more than 1 g. [13] Additional laboratory studies to rule out other causes of neuropathy, as well as cancer and bleeding diathesis, are also important.
Lumbar spine and pelvic radiographs should be performed to evaluate for other causes of the plexopathy. Computed tomography (CT) scanning or magnetic resonance imaging (MRI) of the lumbosacral spine and pelvis may be indicated in some cases to rule out mass lesions. [14] Electromyography (EMG) and nerve conduction studies (NCS) should also be performed. [15, 16]
Management
Good glycemic control through the adjustment of diabetes medication (eg, oral agents, insulin) is of paramount importance. Education on proper diet and exercise is also essential.
Medical management includes neuromodulator medications for chronic neuropathic pain management such as anticonvulsant medications (gabapentin or pregabalin) and selective norepinephrine reuptake inhibitors (such as duloxetine). Anecdotal experience indicates that topical counter-irritant medications such as menthol and wintergreen are also valuable as comfort measures.
A physical therapist (PT) can assist in improving a patient's functional mobility (eg, transfers, ambulation). The PT instructs the patient in the use of assistive devices when necessary. A therapeutic exercise and range-of-motion program supervised by the PT is helpful in maintaining and improving lower extremity prime-mover muscle function and avoiding major lower extremity joint contractures.
An occupational therapist can recommend appropriate adaptive equipment (eg, a reacher, an elevated toilet seat, a tub bench) based on the degree of proximal weakness the patient is experiencing.
Pathophysiology
The underlying pathogenesis of diabetic lumbosacral plexopathy and the site of the lesion are not clearly understood and remain subjects of controversy. [7, 17] The condition is most likely caused by inflammatory, immune-mediated vascular radiculoplexopathy. [18, 19, 20, 21] Most authors now favor an immune vasculopathy as the cause of diabetic amyotrophy. Studies suggest a role for immunomodulating agents in certain types of diabetic neuropathy, including diabetic amyotrophy. [22]
A study by Kotov et al of 445 patients with diabetes mellitus found that diabetic asymmetrical proximal neuropathy was present in 7.9% of this group and that the rate of occurrence was higher in patients with type 2 diabetes mellitus, in those with poorly controlled glycemia, and in patients who had had diabetes for over 5 years. [23]
Epidemiology
In the United States, the overall prevalence of diabetic lumbosacral plexopathy among individuals with diabetes is 0.08%, although the condition occurs more frequently in persons with type 2 diabetes (1.1%) than in those with the type 1 disease (0.3%).
In a study of the population of Olmstead County, Minn., Ng et al found the rate of DM in persons with lumbosacral radiculoplexus neuropathy to be 66.1%, compared with 19.8% in controls. [24]
Morbidity related to diabetic lumbosacral plexopathy is mainly secondary to pain, proximal muscle wasting, and weakness, causing difficulty getting up from a chair and climbing stairs.
No race or sex predilection exists for diabetic lumbosacral plexopathy; however, the condition occurs most commonly in patients aged 50 years or older. In a series of 12 cases reported by Casey and Harrison, no patient was younger than 50 years, and 10 patients were older than 60 years. [25] In a large series of 105 patients with diabetic amyotrophy reported by Bastron and Thomas, the age of onset ranged from 36 to 83 years; symptoms progressed over an average of 6.2 months, with 9.5% of patients having painless muscle weakness. [26] Diabetic lumbosacral plexopathy is rare in children; only 3 cases of the condition in children aged 13-16 years have been reported in the literature.
Prognosis
Good functional recovery within 12-24 months is expected in 60% of patients with diabetic lumbosacral plexopathy, although mild weakness, discomfort, and stiffness often persist for years. Occasional relapses can occur.
Patient Education
The patient should be educated in the importance of good glycemic control in conjunction with proper diet and exercise. [27] During rehabilitation, in order to improve functional recovery, the patient should be taught exercises to regain strength in the affected muscle groups.
