Endocrinology 327

Diagnosis and management of diabetic amyotrophy

About 50% of patients with diabetes mellitus worldwide suffer from diabetic peripheral neuropathy (DPN). The most common form of DPN is a symmetrical, predominantly sensory, polyneuropathy with distal onset and slow proximal progression. However, some patients with diabetes may present with acute or subacute, progressive, asymmetrical weakness and pain of the muscles of the proximal lower limbs. The condition is commonly known as diabetic amyotrophy. Many other names have also been proposed, including Bruns-Garland syndrome, diabetic lumbosacral plexopathy and diabetic lumbosacral radiculoplexus neuropathies. Here, we review its pathogenesis, diagnosis and management.

Dr Subramaniam Nagsayi* Clinical Fellow in Geriatrics, Withybush General Hospital, Haverfordwest, SA61 2PZ Dr Chandrashekaraiah Somasekhar ST3 in Geriatrics, Withybush General Hospital, Haverfordwest, SA61 2PZ Dr Christopher Mark James Consultant in Geriatrics, Withybush General Hospital, Haverfordwest, SA61 2PZ *email [email protected]

The overall prevalence of diabetic without medical treatment but Classification amyotrophy1 (DA) is low and is may be slow and incomplete. higher in patients with type-2 Some patients may also have Diabetic amyotrophy occurs with diabetes (1.1%) than those with a s s o c i a t e d t h o r a c i c a gradual or acute onset, most type-1 diabetes (0.3%). In contrast, radiculopathies or upper limb commonly in patients aged 50 a large proportion (about 50%) of weakness. years or older. The symptoms patients with diabetes mellitus may be the first presentation of across the world suffer from diabetes mellitus, and hence a high diabetic peripheral neuropathy Pathogenesis clinical suspicion is required. The (DPN). condition begins unilaterally and The most common form Diabetic amyotrophy is spreads bilaterally, with pain in the of DPN is a symmetrical, caused by a combination of hip, buttock or thigh, sometimes predominantly sensory autoimmunity, metabolic accompanied by weight loss. polyneuropathy with distal onset derangements, microvascular Proximal muscle weakness and slow proximal progression. insufficiency, oxidative and and wasting in quadriceps, hip A much smaller number of nitrosative stress, and deficiencies adductors, and iliopsoas muscles is patients with diabetes may present in neurohormonal growth characteristic. A mild sensory loss with acute or subacute, factors. Impaired blood flow and is observed due to coexistence with progressive, asymmetrical endoneurial microvasculopathy chronic DPN. weakness and pain in the muscles play critical roles in its The knee-jerk reflex is absent, of the proximal lower limbs (box pathogenesis.2,3 with ankle jerks commonly 1). Both lower limbs can become Metabolic disturbances in the preserved; however, ankle jerks affected to similar degrees as presence of an underlying genetic also may be absent with underlying diabetic amyotrophy progresses. predisposition cause reduced distal symmetrical polyneuropathy. The condition runs a nerve perfusion. A recent review In older patients who have diabetes, monophasic course that can be concluded that this process is the peripheral neuropathies have protracted (up to three years) and result of ischaemic damage to detrimental effects on stability, often causes significant disability. nerves from a multifocal immune- sensorimotor function, gait and Recovery of function occurs mediated microvasculitis.4 activities of daily living (ADL).

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Case study absent ankle reflexes bilaterally from a random blood glucose and an absent knee reflex on the measurement of 14.5mmol/L A 69-year-old woman who right but a preserved reflex on and HbA1c of 11.2%. Nerve was otherwise fit and well, was the left. Plantar flexion conduction studies showed seen by her general practioner was observed bilaterally. bilateral quadriceps denervation for increasing difficulty with Spinothalamic and posterior with ongoing reinnervation walking. It started as weakness column sensations were normal due to axonal sprouting. The in the right leg, then involved in the lower limbs, as was foot drop was presumably due the left leg and thus lead to neurological examination of the to L5/S1 roots involvement. unsteadiness and frequent upper limbs. Perianal sensation MRI of the lumbar and sacral falls. She lost two stone over and anal tone were normal. spine revealed no structural six months with considerable In the clinic, her capillary abnormalities. wasting of her thighs in spite of glucose measurement was Management included strict a good appetite. 12.8mmol/L and urine showed glycaemic control with insulin On examintion, she had 3+ glucose (28mmol/L) and 1+ and intensive physiotherapy. flaccid lower limb weakness with ketones (trace levels). Over the next two months, considerable wasting of both A diagnosis of bilateral her HbA1c improved to 6.8%. quadriceps and calves (more on l u m b o s a c r a l ( m o t o r ) Eight months later, proximal the right). She had a power of 3/5 radiculopathy secondary to new power had improved to 4/5 in the hip and 2/5 at the knee on onset type-2 diabetes mellitus bilaterally, she was mobilising the right and a right foot drop. was made and later confirmed by independently with the aid of a The left hip and knee power was nerve conduction studies. Blood zimmer frame but the right foot 3/5 but 5/5 at the ankle. She had investigations were normal apart drop remained.

Management may be difficult. Tricyclic type (eg, chronic immune antidepressants, antiepileptic demyelinating polyneuropathy It is important to recognise drugs and analgesics are often [CIDP]; see box 2) because the that the condition can be the used as first-line drugs in the latter responds dramatically presenting feature of diabetes treatment plan. t o i m m u n o g l o b u l i n , mellitus. Investigations are It is important to divide plasmapheresis, steroids and described in box 3. Early proximal syndromes, such as immunosuppressive agents.5,6,7,8 recognition, strict glycemic diabetic amyotrophy, into either An opinion from a neurologist to control (with insulin at least an axonal or a demyelinating clarify the above dilemma could initially) and aggressive physiotherapy are the mainstays Box 2: of treatment. Neuropathic pain Classification of diabetic neuropathies may co-exist and treatment 1. Focal neuropathies (mononeuropathies and entrapment Box 1: Differential diagnosis syndromes) 2. Diffuse neuropathies • Cauda equina syndrome Axonal (predominantly proximal such as diabetic amyotrophy) • Guillain barré syndrome Demyelinating (proximal and distal) • Spinal canal stenosis 3. Generalised symmetric polyneuropathies • Neoplastic lumbosacral Acute sensory plexopathy Autonomic • Chronic demyelinating Chronic sensorimotor distal polyneuropathy (large and small neuropathy fibre) (chronic DPN)

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throw light on further treatment options. These conditions Box 3: Laboratory tests should be distinguished from spinal stenosis, which 1. All patients with a suspected peripheral neuropathy should have a is common in the elderly, random blood glucose test because therapy may range 2. Baseline hematinic studies to rule out vitamin B12/folate from simple physical therapy deficiency to surgical decompression. 3. Lumbar puncture if CIDP is suspected 4. Electromyography/nerve conduction studies reveal axonal Conclusion damage in the classic form of proximal motor neuropathy. If it shows demyelination, a diagnosis of CIDP should be considered Diabetes mellitus is the 5. Magnetic resonance imaging of lumbosacral spine to rule out commonest cause for peripheral structural disorders neuropathy and distal sensory neuropathy predominates. neuropathy: a clinicopathologic However, as in the case study diabetic neuropathy. We suggest and immunohistochemical analysis (p. 328), the presentation readers refer to other articles of surval nerve biopsies. Muscle of asymmetric paraparesis, (such as those below) for further Nerve 1996; 29: 722–7 3. Said G, Goulon-Goeau C, Lacroix with minimal or no sensory details on pathogenesis and C, Mouloonguet A. Nerve biopsy involvement, should alert the management. findings in different patterns of physician to the possibility of proximal diabetic neuropathy. Ann diabetic amyotrophy. Early I have no conflict of interest Neurol 1994; 35: 559–69 recognition prevents undue delay 4. Dyck PJ, Windebank AJ. Diabetic in its management, and hence References and nondiabetic lumbosacral radiculoplexus neuropathies: new measurment of blood glucose is insights into pathophysiology and 1. Diabetic lumbosacral plexopathy. necessary when investigating any treatment. Muscle Nerve 2002; 25: Emedicine. http://emedicine. form of peripheral neuropathy. 477–91 medscape.com/article/316151- 5. Fernandes Filho JA, Nathan BM, This article only aims overview Palmert MR, Katirji B. Diabetic to create awareness of an 2. Younger DS, Rosoklija G, Hays amyotrophy in an adolescent uncommon but treatable form of AP, et al. Diabetic peripheral responsive to intravenous immunoglobulin. Muscle Nerve Key points: 2005; 32: 818–20 6. Kawagashirea Y, Watanabe H, Oki Y, et al. Intravenous • Diabetic amyotrophy is a symmetrical, predominantly sensory immunoglobulin therapy markedly polyneuropathy ameliorates muscle weakness and severe pain in proximal diabetic • Distal onset and slow proximal progression neuropathy. J Neurol Neurosurg • More common with type-2 than type-1 diabetes (1.1% vs 0.3%) Psychiatry 2007; 78: 899–901 • Both lower limbs can become affected 7. Wada Y, Yanagihara C, Nishimura Y, Oka N. A case of diabetic • Funcional recovery possible without medical attention amyotrophy with severe atrophy • The condition begins unilaterally and can spread bilaterally and weakness of shoulder girdle muscles showing good response • Symptoms include pain in the hip, buttock or thigh to intravenous immune globulin. • Classify into the axonal or demyelinating type as the latter Diabetes Res Clin Pract 2007; 75: responds dramatically to certain treatments 107–10 8. Krendel DA, Costigan DA, • Treatment includes strict glycemic control and aggressive Hopkins LC. Successful treatment physiotherapy of neuropathies in patients with • Symptoms include pain in the hip, buttock or thigh diabetes mellitus. Arch Neurol 1995; 52: 1053–61

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