Diabetic thoracic radiculopathy: electrodiagnostic study

Diabetic Mononeuropathies and Diabetic Amyotrophy

This brief review describes the etiology, pathophysiology, clinical features, therapy and prognosis of the diabetic mononeuropathies and diabetic amyotrophy and neuropathic cachexia. Mononeuropathies include cranial neuropathies, of which the oculomotor nerve is most commonly affected, and are thought to be due to microvascular occlusion. Peripherally, entrapment neuropathies occur in both the upper and lower limbs and are due to compression of an already damaged nerve in anatomically restricted channels. Diabetic radiculopathies occur in the dermatones of the thorax and abdomen, mimicking intraabdominal or intrathoracic pathology. I also describe the features of the rare but very distinctive diabetic amyotrophy and neuropathic cachexia. Overall, the prognosis from these conditions is excellent with residual pain or muscle weakness being rare with the exception of diabetic amyotrophy where the prognosis is dependent upon cooperation with intensive rehabilitation. Therapies include "watchful waiting," physical therapy and rarely surgical intervention, which may be urgently needed for nerve decompression and reversal of motor defects.

Diabetic thoracic radiculopathy: a case of a young woman with clinical improvement following immunotherapy

Thoracic radiculopathy is a rare cause of thoracic-abdominal or abdominal pain in subjects with poorly controlled diabetes. We present a case of a young woman with type I diabetes and a severe abdominal pain in both lower quadrants. An extensive diagnostic gastroenterological and gynaecological workup did not disclose abnormalities. Electromyography revealed an initial polyneuropathy and significant neurogenic abnormalities in the T10-T12 paravertebral muscles. Following the hypothesis that the radiculopathy-related abdominal pain might have an immuno-mediated pathogenesis, the patient underwent a complex trial of immunotherapy, which was accompanied by a sustained improvement over months to full recovery. This report would support the hypothesis that immune-mediated mechanisms are still active even months after onset of symptoms.

Sensory manifestations of diabetic neuropathies: anatomical and clinical correlations

BACKGROUND

Diabetes mellitus is among the most common causes of peripheral neuropathy worldwide. Sensory impairment in diabetics is a major risk factor of plantar ulcers and neurogenic arthropathy (Charcot joints) causing severe morbidity and high health-care costs.

OBJECTIVE

To discuss the different patterns of sensory alterations in diabetic neuropathies and their anatomical basis.

STUDY DESIGN

Literature review.

METHODS

Review of the literature discussing different patterns of sensory impairment in diabetic neuropathies.

RESULTS

The different varieties of diabetic neuropathies include typical sensorimotor polyneuropathy (lower extremity predominant, length-dependent, symmetric, sensorimotor polyneuropathy presumably related to chronic hyperglycemic exposure, and related metabolic events), entrapment mononeuropathies, radiculoplexus neuropathies related to immune inflammatory ischemic events, cranial neuropathies, and treatment-related neuropathies (e.g. insulin neuritis). None of these patterns are unique for diabetes, and they can occur in nondiabetics. Sensory alterations are different among these prototypic varieties and are vital in diagnosis, following course, treatment options, and follow-up of treatment effects.

CONCLUSIONS

Diabetic neuropathies can involve any segment of peripheral nerves from nerve roots to the nerve endings giving different patterns of abnormal sensation. It is the involvement of small fibers that causes positive sensory symptoms like pain early during the course of disease, bringing subjects to physician's care.

CLINICAL RELEVANCE

This article emphasizes on the fact that diabetic neuropathies are not a single entity. They are rather different varieties of conditions with more or less separate pathophysiological mechanisms and anatomical localization. Clinicians should keep this in mind when assessing patients with diabetes on the first visit or follow-up.

Diabetic neuropathy part 2: proximal and asymmetric phenotypes

Diabetic neuropathies consist of a variety of syndromes resulting from different types of damage to peripheral or cranial nerves. Although distal symmetric polyneuropathy is the most common type of diabetic neuropathy, many other subtypes have been defined since the 1800s, including proximal diabetic, truncal, cranial, median, and ulnar neuropathies. Various theories have been proposed for the pathogenesis of these neuropathies. The treatment of most requires tight and stable glycemic control. Spontaneous recovery is seen in most of these conditions with diabetic control. Immunotherapies have been tried in some of these conditions however are controversial.

Diabetic thoracic polyradiculopathy

Diabetic thoracic polyradiculopathy usually causes severe, chronic abdominal pain in patients with type 2 diabetes of variable duration. Other diabetic complications, weight loss and paretic abdominal wall protrusion are common. Sensory, motor and autonomic functions are affected. The diagnosis can be made from the characteristic history, physical examination findings, paraspinal electromyography, and other procedures. The differential diagnosis includes postherpetic neuralgia, abdominal wall pain, malignancy, and other spinal disorders. The pathology appears to be immune-mediated neurovasculitis resulting in ischemic injury. Traditional therapy is symptomatic, but recent pathological findings and clinical experience suggest that immunotherapy may be effective.

Chronic abdominal wall pain: a frequently overlooked problem. Practical approach to diagnosis and management

Chronic abdominal wall pain is frequently misdiagnosed as arising from a visceral source, often resulting in inappropriate diagnostic testing, unsatisfactory treatment, and considerable cost. Its prevalence in general medical practice is unknown, although it may account for about 10% of patients with chronic idiopathic abdominal pain seen in gastroenterological practices. The most common cause appears to be entrapment of an anterior cutaneous branch of one or more thoracic intercostal nerves; myofascial pain and radiculopathy are less frequent. Sharply localized pain and superficial tenderness are suggestive of abdominal wall origin. Carnett's test (accentuated localized tenderness with abdominal wall tensing) is a helpful diagnostic sign, especially when incorporated with other findings. Early exclusion of a parietal source should increase diagnostic accuracy when evaluating patients with chronic abdominal pain. Reassurance of patients by the correct diagnosis and avoidance of precipitating causes is often sufficient treatment. However, accurately placed anesthetic/corticosteroid injections give substantial pain relief to more than 75% of patients, often for prolonged periods, and may be confirmatory for the source of the complaint. The probability of missing visceral disease is small (probably less than 7%) with strict adherence to diagnostic criteria and diligent observation of patients.

Electrophysiology of radiculopathies

The anatomy, pathophysiology, and clinical evaluation of radiculopathies are discussed. Defining whether root injury is present and which roots are involved can be difficult but critical for patient management. In conjunction with clinical and radiological information, studies that establish physiological abnormalities of roots should be helpful and important. Clinical neurophysiological studies for radiculopathies are performed frequently but have yet to achieve a universally accepted role in the evaluation of these patients. Electrophysiological techniques for the evaluation of radiculopathies are reviewed. Needle electromyography is the best established of these procedures but has the disadvantage of requiring injury to motor fibers of both a certain degree and distribution. Nerve conduction studies may rarely be abnormal in radiculopathies but are needed to be certain other conditions that may produce similar symptoms and signs are not present. H reflexes and F waves probably have roles in the evaluation of radiculopathies but published reports about F waves in radiculopathies have been marred by inadequate methodology. There is evidence based on large series of patients that somatosensory evoked potentials can be helpful for evaluating patients with multilevel injury such as spinal stenosis, patients where electrophysiological studies may have their greatest clinical utility. Further work using either electrical stimulation with needles or magnetic stimulation of roots seems warranted. The demonstration of meaningful electrophysiological changes with activities that reproduce radicular symptoms may be a promising experimental approach. Available information does not necessarily answer critical questions about the role of electrophysiology in patients with radiculopathies. This cannot be done using analyses based on current ideas about evidence based medicine given the absence of a 'gold standard' for defining radiculopathies as well the absence of blinded studies. The available information provides strong arguments for further investigations evaluating different clinical neurophysiological techniques in the same patient, and for evaluating the value of these techniques by concentrating on their clinical import.

Diabetic Lumbosacral Polyradiculoneuropathies

The pathogenic basis and treatment of diabetic polyradiculoneuropathy is a source of recent controversy as there may be two or more distinct forms of diabetic polyradiculoplexopathy. We believe that the following two categories of diabetic polyradiculoneuropathy can be made on the basis of clinically differences: 1) the more common asymmetric, painful polyradiculoneuropathy; and 2) the rare symmetric, painless, polyradiculoneuropathy. The asymmetric, painful form (also known as diabetic amyotrophy) may have an autoimmune basis, but the etiology is not clear. The natural history for diabetic amyotrophy is spontaneous improvement. Nevertheless, various immunotherapies (eg, corticosteroids and intravenous immunoglobulin (IVIg) have been tried with subsequent improvement in symptoms. Treatment is reserved only for patients with severe ongoing pain, given the significant side effects of these medications in those patients with diabetes. Prednisone and IVIg may help alleviate the pain associated with diabetic amyotrophy. Relief of pain can help patients begin physical therapy earlier, however, there are no prospective, blinded, controlled studies that demonstrate that these treatments lead to an earlier and better recovery of muscle strength compared with the natural history of the disorder. The symmetric, painless form of diabetic polyradiculoneuropathy may in fact represent chronic inflammatory demyelinating polyneuropathy (CIDP) occurring in a patient with diabetes mellitus (DM). Patients with idiopathic CIDP may improve various immunomodulating therapies, including corticosteroid treatment, plasma exchange (PE), and IVIg. In this regard, patients with the symmetric, painless, proximal diabetic polyradiculoneuropathy may also respond to corticosteroids, plasma exchange, IVIg, azathioprine, or cyclophosphamide. However, as with diabetic amyotrophy, some patients improve spontaneously without treatment. In still other patients, the neuropathy appears unresponsive to immunotherapy. In such patients, this polyradiculoneuropathy might be caused by metabolic dysfunction associated with DM. Unfortunately, from a clinical, laboratory, and electrophysiologic standpoint, it is impossible to distinguish the patients with a symmetric, painless diabetic polyradiculoneuropathy who might respond to therapy. A trial of PE can be useful in identifying patients who might have a polyradiculoplexopathy that is responsive to immunotherapy. If patients respond to PE, they may continue to receive intermittent exchanges or be switched over to prednisone or IVIg.

Diabetes and the gastrointestinal tract

Gastrointestinal motility disorders are common in patients with diabetes. The entire gastrointestinal tract may be involved from the esophagus to the anal sphincter. Before instituting therapy, people with diabetes first require a careful diagnostic evaluation. Treatment includes tight glucose control and the use of antiemetics and prokinetic agents.

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.

Reflexes evoked in human erector spinae muscles by tapping during voluntary activity

We studied the stretch reflexes, an early R1 and a late R2, by tapping the voluntarily contracted erector spinae muscles and recording from the same spinal level with the subject in the prone position. The onset latencies increased progressively towards the caudal level from 8.8 +/- 0.7 ms at T5-6 to 15.9 +/- 1.1 ms at L4-5 for R1, and from 33.3 +/- 2.7 ms at T5-6 to 49.1 +/- 2.8 ms at L4-5 for R2. The latency changed significantly (P < 0.05) between two adjacent segments from T5-6/T6-7 through L1-2/L2-3 for R1 and T5-6/T6-7 through L3-4/L4-5 for R2. When recorded remote from the stimulus site, R1, considered segmental in origin, showed, as expected, only a small latency change consistent with the time required for the mechanical event to propagate to the recording site. In contrast R2 was shorter in latency with more rostral stimulation irrespective of the distance to the recording sites. This finding implies a centripetal propagation of the afferent impulse along the central pathway, which shortens with more rostral site of stimulation. Of the two components, the more reproducible R1 has a potential diagnostic value for segmental evaluation of thoracic nerve root compression and truncal neuropathies.

[Abdominal neuropathy of motor expression of diabetic origin. Apropos of a case]

Authors report a case of diabetic truncal neuropathy presenting as a painful abdominal swelling. This entity, which frequently is probably under estimated, may mimic abdominal visceral pathology and patients may be subjected unnecessary to extensive diagnosis procedures.

Intercostal nerve conduction study in man

A new surface technique for the conduction study of the lower intercostal nerves has been developed and applied to 30 normal subjects. The problem of the short available nerve segment of the intercostal nerves and the bizzare compound motor action potential (CMAP) of inconsistent latency while recording over the intercostal muscles, is overcome by applying recording electrodes over the rectus abdominis muscle and stimulating the nerves at two points at a fair distance away. With the use of multiple recording sites over the rectus abdominis, the motor points for different intercostal nerves were delineated. CMAP of reproducible latencies and waveforms with sharp take-off points were obtained. Conduction velocity of the intercostal nerves could be determined.

Diabetic truncal neuropathy: topography of the sensory deficit

The distributions of sensory abnormalities in 17 episodes of diabetic truncal neuropathy among 7 patients with diabetes mellitus are described. The patterns are highly variable: the distribution of adjacent main spinal nerves may be involved, resulting in a complete dermatomal band of dysesthesia, but almost two-thirds of the episodes were restricted to the distribution of the ventral or dorsal rami of the spinal nerves or branches of these rami or varying combinations of these distributions.

Clinical aspects of diabetic neuropathies

Diabetic neuropathy is a common complication of diabetes that may be associated both with considerable morbidity (painful polyneuropathy, neuropathic ulceration) and mortality (autonomic neuropathy). The epidemiology and natural history of diabetic neuropathy is clouded with uncertainty, largely due to confusion in the definition and measurement of this disorder. We have reviewed a variety of the clinical manifestations associated with somatic and autonomic neuropathy and discussed current views related to the management of the different abnormalities. Although unproven, the best evidence suggests that near normal control of blood glucose in the early years following onset of diabetes may help delay the development of clinically significant nerve impairment. Intensive therapy to achieve normalization of blood glucose may also lead to reversibility of early diabetic neuropathy, but again this is unproven. Our ability to manage successfully the many different manifestations of diabetic neuropathy depends ultimately on our success in uncovering the pathogenic processes underlying this disorder. The recent resurgence of interest in the vascular hypothesis, for example, has opened up new avenues of investigation for therapeutic intervention. Paralleling our increased understanding of the pathogenesis of diabetic neuropathy, there must be refinements in our ability to measure quantitatively the different types of defects that occur in this disorder. These tests must be validated and standardized to allow comparability between studies and more meaningful interpretation of study results.

[Electrophysiological studies in the assessment of polyneuropathies]

In many cases, one encounters great difficulties in finding causes of polyneuropathies among some 100 etiologies. However, in current practice, the diagnostic span is not so large. At this point, it is usual to get some aid from electrophysiologic tests in order to determine the nature of the peripheral nerve disorder. Examination with needle electrodes is mainly useful to detect fibrillation potentials or positive sharp waves which are indicative of an acute or subacute axonal neuropathy in which the process of degeneration is more important than the capacities of regeneration. Studies of sensory and motor nerve conduction velocities is of a more important utility to separate the different types of peripheral neuropathies: axonopathies in which nerve conduction velocities are normal or slightly decreased but in which muscular evoked potentials and sensory potentials are reduced, myelin disorders in which nerve conduction velocities are markedly decreased and in which finding of conduction blocks allows to individualize two forms, motor and sensory neuronopathies, where the pure lesion of the motor or sensory cell bodies correlate with the normality of sensory and motor pathways respectively.