Diabetic amyotrophy: a follow-up study

Spectrum of diabetic neuropathies

The diabetic state results in neuropathy. The main causative mechanism is hyperglycemia, although microvascular involvement, hypertriglyceridemia, as well as genetic and immune mechanisms may be contributory. There is a growing spectrum of types of diabetic neuropathies that differ based on the type of fibers involved (e.g. myelinated, unmyelinated, autonomic, somatic), distribution of nerves involved, and mechanisms of neuropathy. The most common type is distal sensory neuropathy (DSN), which affects the distal ends of large myelinated fibers, more often sensory than motor, and is often asymptomatic. The next-most common is distal small fiber neuropathy (DSFN), which largely affects the unmyelinated fibers and carries the phenotype of burning feet syndrome. Diabetic autonomic neuropathy (DAN) occurs when widespread involvement of autonomic unmyelinated fibers occurs, and patients can be incapacitated with orthostatic hypotension as well as neurogenic bladder and bowel involvement. Radiculoplexus diabetic neuropathy causes proximal weakness and pain, usually in the lower extremity, and has a combination of immune, inflammatory, and vascular mechanisms. The nerve roots and plexus are involved. These patients present with proximal weakness of a subacute onset, often with severe pain and some autonomic failure. Finally, rapid and sustained reduction of blood glucose can result in treatment-induced diabetic neuropathy (TIND), which largely affects the sensory and autonomic fibers. This occurs if HbA1c is rapidly reduced within 3 months, and the likelihood is proportional to the original A1c and the size of the reduction.

Diabetic Amyotrophy: From the Basics to the Bedside

Diabetic amyotrophy is a rare complication of diabetes compared to distal symmetric polyneuropathy, but can occasionally be encountered in clinical practice, particularly as the incidence of diabetes increases. The distinctive history of unilateral neuropathic symptoms followed rapidly by atrophy and weakness is typical of the disorder. This complication most commonly occurs in cases of well-controlled Type 2 diabetes mellitus. While the underlying pathophysiology is known to be microvasculitic in nature, the diagnosis is often based on clinical and electrodiagnostic grounds and tissue biopsy is not typically performed. Attempts at corticosteroid administration during immunotherapy should be carefully considered on a patient-by-patient basis. Better recognition of this disorder is likely to result in more rapid diagnosis, counselling, and subspecialty referral.

Acute diabetic neuropathy following improved glycaemic control: a case series and review

SUMMARY

We present three cases of acute diabetic neuropathy and highlight a potentially underappreciated link between tightening of glycaemic control and acute neuropathies in patients with diabetes. Case 1: A 56-year-old male with poorly controlled type 2 diabetes (T2DM) was commenced on basal-bolus insulin. He presented 6 weeks later with a diffuse painful sensory neuropathy and postural hypotension. He was diagnosed with treatment-induced neuropathy (TIN, insulin neuritis) and obtained symptomatic relief from pregabalin. Case 2: A 67-year-old male with T2DM and chronic hyperglycaemia presented with left lower limb pain, weakness and weight loss shortly after achieving target glycaemia with oral anti-hyperglycaemics. Neurological examination and neuro-electrophysiological studies suggested diabetic lumbosacral radiculo-plexus neuropathy (DLPRN, diabetic amyotrophy). Pain and weakness resolved over time. Case 3: A 58-year-old male was admitted with blurred vision diplopia and complete ptosis of the right eye, with intact pupillary reflexes, shortly after intensification of glucose-lowering treatment with an SGLT2 inhibitor as adjunct to metformin. He was diagnosed with a pupil-sparing third nerve palsy secondary to diabetic mononeuritis which improved over time. While all three acute neuropathies have been previously well described, all are rare and require a high index of clinical suspicion as they are essentially a diagnosis of exclusion. Interestingly, all three of our cases are linked by the development of acute neuropathy following a significant improvement in glycaemic control. This phenomenon is well described in TIN, but not previously highlighted in other acute neuropathies.

LEARNING POINTS

A link between acute tightening of glycaemic control and acute neuropathies has not been well described in literature. Clinicians caring for patients with diabetes who develop otherwise unexplained neurologic symptoms following a tightening of glycaemic control should consider the possibility of an acute diabetic neuropathy. Early recognition of these neuropathies can obviate the need for detailed and expensive investigations and allow for early institution of appropriate pain-relieving medications.

Diabetic amyotrophy (Bruns-Garland syndrome)

Garland and Taverner first fully described diabetic amyotrophy as a clinical entity in 1950. Its distinctive features were a painful, markedly asymmetrical proximal weakness and wasting of the thighs and legs often with diminished or absent tendon reflexes. Motor signs dominated the picture, but autonomic and sensory nerves could be involved.  Characteristically it occurred in poorly controlled diabetics in whom substantial if not always complete recovery was generally observed. A lumbosacral plexus neuropathy, associated with microvasculitis with secondary inflammatory perivascular mononuclear cell infiltrates is the underlying pathology.

Diabetic neuropathy: achieving best practice

Peripheral neuropathy is one of the commonest complications of diabetes and the commonest form of neuropathy in the developed world.1 Diabetic polyneuropathy encompasses several neuropathic syndromes, and the commonest presentation is chronic distal symmetrical neuropathy (DSP). DSP, often associated with autonomic neuropathy, has two clinical consequences: namely neuropathic pain and foot ulceration. Both often occur in the same individual, and cause severe curtailment of quality of life. The other, less common presentations of diabetic polyneuropathy include acute painful neuropathies, and focal neuropathies (amyotrophy, pressure palsies, truncal radiculopathies, mononeuropathies and mononeuritis multiplex).2 Table 1 shows a recent classification of diabetic polyneuropathy based upon the natural history of the various syndromes.3

[Skeletal muscle magnetic resonance imaging study in a patient with diabetic lumbosacral radiculoplexus neuropathy]

A 63-year-old man with type 2 diabetes mellitus developed deep aching and numbness in the right hip and lower extremity with rapid body weight loss. Neurological examination revealed weakness of the right hamstrings, tibialis anterior, and peroneus longus muscles with diminished ankle tendon reflex. We diagnosed him with diabetic lumbosacral radicuoloplexus neuropathy (DLRPN) based on neurological, radiological, and neurophysiological findings. Magnetic resonance imaging (MRI) of skeletal muscles showed high intensity signals on T2-weighted images in bilateral hamstrings, adductor magnus and right tensor fasciae latae, and lower leg extensor muscles. The MRI findings suggested muscle edema caused by acute denervation. DLRPN, or diabetic amyotrophy, is known to be caused by ischemic axonal degeneration. Our patient showed good functional recovery, and abnormal MRI signals in the involved muscles mostly disappeared in parallel to the clinical course. Distribution of the denervated muscles suggested that our patient had either patchy lesions in the lumbosacaral plexus or mononeuropathy multiplex in the nerve branches. The current study highlights the potential of skeletal muscle MRI for clinical evaluation of DLRPN.

Effect of diabetes mellitus on muscle size and strength in patients receiving dialysis therapy

BACKGROUND

Diabetes mellitus (DM) is a potential contributor to the muscle abnormalities and poor physical functioning of the dialysis population.

METHODS

Thirty-three dialysis patients without DM (non-DM group) were compared with 25 dialysis patients with DM (DM group). Measures were made of cross-sectional area and composition of the leg muscles by using proton T1-weighted magnetic resonance imaging; body composition by means of dual-energy X-ray absorptiometry; leg muscle strength by means of isokinetic knee extension; isometric dorsiflexor maximum voluntary contraction by means of force plate; physical activity by means of 3-dimensional accelerometry; and functional capacity by using various functional tests.

RESULTS

The DM group was older, weaker, more atrophic, and had a greater amount of intramuscular fat compared with the non-DM group. However, when the overall analysis was adjusted for age and sex, there were no differences between the 2 groups with respect to muscle cross-sectional area, leg strength, or physical activity. To further account for sex and age differences, a paired analysis was performed after matching patients by age (within 5 years) and sex (N = 16/group). In the matched analysis, only intramuscular fat and leg adipose tissue were different between the 2 groups.

CONCLUSION

DM is associated with more fat within muscles of dialysis patients, but is unrelated to muscle size or strength. Demographic differences between the DM and non-DM groups on dialysis therapy likely are responsible for the general perception that patients with DM are more debilitated.

Understanding the impact of painful diabetic neuropathy

Painful neuropathy is a common and often distressing complication of diabetes. It has considerable impact on the social and psychological well-being of affected individuals. There are two distinct forms of painful neuropathy: an acute and self-limiting form that resolves within a year or a chronic form that can go on for years. There are now a number of drugs available for the treatment of neuropathic pain. However, some may fail to respond to these drugs or may have unacceptable adverse side effects. When this is the case, the patient's quality of life can be severely affected. Health care professionals need to assess the full impact of painful neuropathy. In this article we review a number of instruments that are used to assess the severity of painful neuropathy and its impact on the quality of life.

Epineurial microvasculitis in proximal diabetic neuropathy

Amongst the focal and multifocal neuropathies that are associated with diabetes mellitus one of the most common is a proximal predominantly motor lower limb neuropathy. Recent evidence has indicated that, at least in a proportion of cases, this may have an inflammatory basis. We have examined a consecutive series of 15 cases of proximal diabetic neuropathy (diabetic amyotrophy). These were characterized by proximal pain and asymmetric proximal or generalized lower limb muscle weakness, associated in some cases with radicular sensory involvement. Two-thirds of the patients had an accompanying distal symmetric sensory polyneuropathy. Biopsy of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, showed epineurial microvasculitis in 3 patients and nonvasculitic epineurial inflammatory infiltrates in another case. In a further case, microvasculitis was found in both in the sural nerve and a quadriceps muscle biopsy specimen. The detection of inflammatory changes appeared to be correlated with the occurrence of sensory radicular involvement. Whether similar changes are present in muscle nerves in this predominantly motor syndrome requires further study. Nevertheless, the present observations confirm the view that secondary vasculitic or other inflammatory reactions may contribute to some forms of diabetic neuropathy.

Autoimmune diabetic neuropathy

Recent work has shown that inflammatory vasculopathy is commonly seen in biopsies of diabetic patients with neuropathy. Most of these patients have had syndromes consistent with proximal diabetic neuropathy or amyotrophy. This suggests that inflammatory vasculopathy is important in the pathogenesis of these disorders. Immunosuppressive therapy may benefit many of these patients.

Endocrinologic causes of peripheral neuropathy. Pins and needles in a stocking-and-glove pattern and other symptoms

In the Western world, diabetes is the biggest cause of peripheral neuropathy, usually distal symmetric polyneuropathy but some times another polyneuropathy or a focal neuropathy. In addition, hypothyroidism and acromegaly can cause carpal tunnel syndrome and other sensory complaints. A complete blood cell count, nerve-conduction tests, thyroid-function tests (needed in all patients with carpal tunnel syndrome), and when necessary, needle electromyography can help confirm the diagnosis. Treatment of underlying disease is the most successful management approach: Tight glucose control in diabetic patients, thyroid hormone replacement therapy in patients with hypothyroidism, and removal of the pituitary adenoma in patients with acromegaly are of proven benefit. Significant symptomatic relief of dysesthesias can be obtained with use of capsaicin cream, tricyclic antidepresants, anticonvulsant agents, or an antiarrhythmic drug.

Diabetic neuropathy

The most common form of diabetic neuropathy is chronic, distal symmetrical sensorimotor, or predominantly sensory neuropathy; the latter is invariably associated with some degree of autonomic dysfunction. There are, however, other neuropathic patterns in diabetes mellitus that are uncommon but are important to recognize, since they may mimic many other non-neurologic diseases. This article discusses a variety of forms of mononeuropathies and diabetic proximal motor neuropathy, commonly known as diabetic amyotropy.

Painful proximal diabetic neuropathy: inflammatory nerve lesions and spontaneous favorable outcome

Proximal diabetic neuropathy is a disabling neuropathy that occurs predominantly in non-insulin-dependent diabetic patients over the age of 50. Inflammatory lesions have been found in nerve biopsy specimens of diabetic patients with severe proximal neuropathy or with other patterns of multifocal neuropathy. Some of these patients respond dramatically to treatment with corticosteroids or with other immunomodulators. In this article we report on our findings in 4 additional patients with painful proximal diabetic neuropathy and different patterns of inflammatory nerve lesions whose condition improved spontaneously shortly after performance of a nerve biopsy, without additional treatment.

AAEM case report #13: diabetic amyotrophy

A case fulfilling the criteria for the diagnosis of diabetic amyotrophy is reported. Based on the clinical and electrodiagnostic features, it is concluded that diabetic amyotrophy is a recognizable clinical entity that can be differentiated from other diabetic neuropathies. The site of the lesion and the pathogenesis in diabetic amyotrophy remain controversial. The course of the illness is variable with gradual, but often incomplete, improvement.

Diabetic neuropathy: an update

Diabetic neuropathy is the most common neuropathy in industrialized countries, with a remarkable range of clinical manifestations. The usual pattern is a distal symmetrical sensory polyneuropathy, associated with autonomic disturbances. Less often, diabetes is responsible for a focal or multifocal neuropathy affecting cranial nerves, especially oculomotor nerves, and roots and nerves innervating proximal muscles of the lower limbs. Metabolic abnormalities due to hyperglycaemia, lack of insulin and their consequences and ischaemic phenomena secondary to diabetic microangiopathy account for nerve lesions.

Acute painful diabetic neuropathy following severe weight loss

A 34-year-old man, recently diagnosed as diabetic, presented an acute painful neuropathy. He reported a profound weight loss during the months preceding onset. There were no motor symptoms, and only mild neurological signs were observed on examination. Improvement was related to a good glycemic control and weight gain. Acute painful diabetic neuropathy is a condition that may affect diabetic patients shortly after development of the disease. The pathogenetic roles played by different factors are reviewed.

Nerve biopsy findings in different patterns of proximal diabetic neuropathy

Besides distal symmetrical sensory polyneuropathy (DSSP), middle-aged diabetic patients may present with focal or multifocal neuropathies, including proximal neuropathy of the lower limbs, the pathophysiological features of which are uncertain. We studied 10 non-insulin-dependent diabetic patients, 45 to 72 years of age, who developed a painful proximal neuropathy of the lower limbs for which other causes of neuropathy were carefully excluded. The proximal neuropathy was asymmetrical in all patients, sensory in 4, motor and sensory in the others. Signs of DSSP were present in all. A sample of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, was taken by biopsy and examined by light and electron microscopy. Examination of the nerve specimens revealed ischemic nerve lesions in 3 patients. Nerve ischemia was associated with vasculitis and inflammatory infiltration in 2 of them. In the other patients the lesions of the cutaneous nerve of the thigh included a varying incidence of axonal and demyelinative lesions similar to those observed in DSSP, with mild inflammatory infiltration in 4 of them. The density of myelinated and of unmyelinated was variably decreased. This study shows that axonal and demyelinative lesions similar to those found in diabetic DSSP are present in proximal nerves in mild forms of proximal diabetic neuropathy; while nerve ischemia, inflammatory infiltration, and vasculitis are encountered in the most severe forms of proximal diabetic neuropathy.

Neuropathies associated with diabetes

Diabetic neuropathy is the most frequent complication of diabetes and the leading cause of polyneuropathy in the Western world. A distal symmetric predominantly sensory polyneuropathy is the most common of the diverse neuropathies that occur secondary to diabetes. Pain is often the most bothersome and difficult to treat symptom of diabetic neuropathy. Autonomic neuropathy is a frequent feature of diabetic neuropathy and the source of many significant problems including postural hypotension, gastroparesis, diarrhea, constipation, neurogenic bladder, and male impotence. Physicians need to be familiar with the multiple, less common forms of diabetic neuropathy, as these often mimic other medical or neurologic conditions. The cause of diabetic neuropathy is not determined, but abundant evidence suggests that both metabolic and ischemic nerve injury are likely factors. These should not be considered mutually exclusive causes of diabetic neuropathy as both factors likely operate to different degrees to produce the clinical spectrum of neuropathies that are seen in diabetes. Although no effective treatment exists to cure diabetic neuropathy, improvement is possible with glycemic control and symptomatic therapy.

Clinical observations and experiments in diabetic neuropathy

Diabetic neuropathies form a group of diverse conditions, which can be distinguished between those which recover (acute painful neuropathies, radiculopathies, mononeuropathies) and those which progress (sensory and autonomic neuropathies). These two main groups can be distinguished in several ways: sensory and autonomic neuropathies are classic diabetic complications progressing gradually in patients with long-standing diabetes who often have other specific complications, while the reversible neuropathies do not have these features. The latter are characterised by their occurrence at any stage of diabetes, often at diagnosis, they may be precipitated on starting insulin treatment, and they are more common in men; they can occur at any age, though more often in older patients, and are unrelated to other diabetic complications. The two groups of neuropathies also show differences in nerve structural abnormalities and with regard to distinctive blood flow responses. The underlying mechanisms responsible for these very different forms of neuropathy remain speculative, but evidence for an immunological basis for the development of severe symptomatic autonomic neuropathy is presented.

Proximal skeletal muscle alterations in streptozotocin-diabetic rats: a histochemical and morphometric analysis

The response of rat quadriceps muscle fibers to chronic streptozotocin (STZ) diabetes was studied. Transverse sections of rectus femoris muscle from diabetic and weight-matched control rats were assayed for myofibrilar adenosine triphosphatase (ATPase) and nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR). A quantitative analysis was carried out by an automatic interactive analysis system focused on the fiber type size and distribution. STZ-induced diabetes caused important effects in this muscle, with changes in the distribution of oxidative enzyme reactions, type I fiber hypertrophy, and type II fiber atrophy, which was greater in type IIB than in type IIA. It is concluded that hypoinsulinism produces morphological alterations in proximal skeletal muscle fibers that are similar to those of neurogenic myopathy. Thus the pathological changes in these mammalian muscle fibers could explain the clinical syndrome seen in diabetic patients called "diabetic symmetrical proximal motor neuropathy," perhaps the least understood of the major neuropathic complications of diabetes.

Diabetic amyotrophy without pain. A puzzling clinical picture

A patient with weight loss and weakness presents a diagnostic challenge. Drs Moeser and Kent describe an unusual case of diabetic amyotrophy that required extensive workup to arrive at the diagnosis and rule out more serious disease. Symptoms were dramatic, and recovery was spontaneous following conservative treatment.

Diabetic amyotrophy: reassessment of the clinical spectrum

Diabetic amyotrophy is a syndrome whose recognition may be difficult or delayed. We reviewed thirteen patients with this disorder, all of whom had significant proximal lower limb wasting and weakness as the predominant feature and eleven of whom had pain in the affected limbs. Significant weight loss was common. In nine patients the deficits were largely or totally reversible. Important variations from the classical features were observed. Only five patients displayed asymmetric proximal lower limb wasting, weakness and pain, motor deficits in the remainder being either unilateral or bilateral and symmetrical. The shoulder girdle and arms were also involved in two patients. Proximal limb pain was not invariable, a distal sensory peripheral neuropathy was common, and diabetic control at diagnosis was likely to be good. No prognostic factors were identified. Thus, not all patients with diabetic amyotrophy exhibit the classically-described features. Other than careful clinical examination, a thorough bilateral electromyographic and nerve conduction study remains the most helpful diagnostic test. Appreciation of the clinical spectrum and context of diabetic amyotrophy should facilitate its differentiation from other disorders, including other forms of diabetic neuropathy.

AAEE case report #13: diabetic amyotrophy

A case fulfilling the criteria for the diagnosis of diabetic amyotrophy is reported. Based on the clinical and electrodiagnostic features, it is concluded that diabetic amyotrophy is a recognizable clinical entity that can be differentiated from other diabetic neuropathies. The site of the lesion and the pathogenesis in diabetic amyotrophy remain controversial. The usual course of the illness is one of gradual improvement over weeks to months.

Diabetic neuropathies and pain

Many of the diabetic neuropathic syndromes are characterized by painful symptoms with a sensation of burning and associated with troublesome hyperaesthesia. It is important to distinguish between the acute and chronic forms of peripheral sensory neuropathy; while the former carries an excellent prognosis for symptomatic improvement within one year, the latter may cause persistent symptoms for many years. In contrast to the acute form, in which symptoms are particularly severe but abnormal neurological signs are minimal, patchy stocking and glove sensory loss together with peripheral small muscle wasting are often present in chronic sensorimotor neuropathy. Peripheral polyneuropathies are more common in patients with poor metabolic control, although recent evidence implicates blood glucose flux as a possible contributory factor to neuropathic pain. It is possible that blood glucose flux or altered peripheral blood flow leads to increased spontaneous activity in nociceptive afferent fibres which are present in the axonal sprouts that characterize small fibre neuropathy. In the diagnosis of the neuropathies, exclusion of other aetiological factors is of paramount importance as there is no specific diagnostic test for diabetic nerve damage. If there is no symptomatic improvement after a period of stable and optimal metabolic control together with simple analgesics, then the tricyclic drugs should be regarded as first line therapy. The rapid effect of these drugs suggests a peripheral rather than central mode of action.

Diabetic polyradiculopathy simulating lumbar disc disease. Report of four cases

Most clinicians are aware of the common neurological effects of endocrine disorders. However, involvement of the spinal nerve roots is a poorly recognized complication of diabetes mellitus. Such involvement can closely simulate more common spinal diseases and thus lead to inappropriate therapy. Four cases of diabetic polyradiculopathy simulating lumbar disc disease are reported, and this distinctive entity is reviewed.

Diabetic neuropathy

Peripheral nerve disorders are important late complications of diabetes mellitus. Polyneuropathy, which may involve varying proportions of sensory, motor, and autonomic fibers, is considered the consequence of metabolic derangements that result from chronic hyperglycemia. Symmetrical proximal motor neuropathy ("diabetic amyotrophy") also may have a metabolic basis. Mononeuropathies in diabetes may have an ischemic or compressive cause. Advances have been made in understanding the biochemical basis for diabetic polyneuropathy. The treatment of symptomatic diabetic neuropathy should be directed toward long-term normalization of blood glucose until more specific therapies become available.

Diabetic proximal neuropathy. Clinical and electromyographic studies

Clinical and electromyographic findings in 27 diabetics with proximal lower extremity weakness were analyzed. Two groups could be distinguished: patients in whom electromyographic findings were restricted to the clinically involved parts of the lower extremity (group A) and those in whom an associated distal symmetric, peripheral neuropathy could be proved on clinical and electromyographic grounds (group B). Patients in group B had significantly greater incidence of the following features: gradual onset of symptoms, bilateral proximal lower extremity weakness, insulin dependency, recent weight loss, EMG evidence of bilateral disease and paraspinal fibrillations. These findings concur with recent reports describing heterogeneity in the syndrome of "diabetic proximal neuropathy".

Diabetic neuralgic amyotrophy

A rare neurological condition, neuralgic amyotrophy, in a diabetic is reported. Strong evidence for a causal relationship is suggested. Comment is made on striking similarities between the clinical presentation and course of both diabetic and neuralgic amyotrophy, inferring a similar end pathological process.

Wasted leg syndrome: a clinical, electrophysiological and histopathological study

Forty cases of 'wasted leg syndrome' were studied clinically and electrophysiologically. Muscle biopsy was examined in nine cases, majority of patients were adults engaged in heavy manual work. The illness was noticed incidently with a strictly unilateral wasting of the whole lower limb (in 65% of cases), of all muscles below the knee (in 22.5% of cases) or of quadriceps muscles only (in 12.5% of cases). The nerve conduction studies and the electromyographic pattern suggested anterior horn cell disorder. Neurogenic atrophy was seen in 7 out of 9 muscle biopsies. A follow up in 12 patients (2-6 years) revealed no progression of the disease. It is suggested that possibly these cases represent an entity, clinically different from other anterior horn cell disorders.

The syndrome of diabetic amyotrophy

Changes in the electromyograms and motor nerve conduction velocities in 12 patients with diabetic amyotrophy suggested mild distal and moderate proximal neuropathy in the lower limbs. Histological and histochemical findings in the vastus medialis muscles were consistent with denervation. Electron microscopical examination of the vastus medialis muscles in 6 patients revealed myofibrillar degeneration. One patient had abnormal mitochondria and tubular aggregates. The basement membranes of the intramuscular capillaries were thickened in all but 1 patient. Histochemical staining of the myoneural junctions showed changes consistent with degeneration and regeneration. We conclude that diabetic amyotrophy is a distinct clinical entity and is secondary to metabolic derangement rather than diabetic microangiopathy.