endocrine and metabolic disorders
Complications of Diabetes Mellitus
Diabetic Neuropathy
Diabetic neuropathy is the result of nerve ischemia due to microvascular disease, direct effects of hyperglycemia on neurons, and intracellular metabolic changes that impair nerve function. There are multiple types, including Symmetric Polyneuropathy (with small- and large-fiber variants) Autonomic Neuropathies None Nerve Root Disorders None Cranial neuropathy Mononeuropathies None Symmetric polyneuropathyis most common and affects the distal feet and hands (stocking-glove distribution); it manifests as paresthesias, dysesthesias, or a painless loss of sense of touch, vibration, proprioception, or temperature. In the lower extremities, these symptoms can lead to blunted perception of foot trauma due to ill-fitting shoes and abnormal weight bearing, which can in turn lead to foot ulceration and infection or to fractures, subluxation, and dislocation or destruction of normal foot architecture (Charcot arthropathy). Small-fiber neuropathy is characterized by pain, numbness, and loss of temperature sensation with preserved vibration and position sense. Patients are prone to foot ulceration and neuropathic joint degeneration and have a high incidence of autonomic neuropathy. Predominant large-fiber neuropathy is characterized by muscle weakness, loss of vibration and position sense, and lack of deep tendon reflexes. Atrophy of intrinsic muscles of the feet and foot drop can occur. can cause Orthostatic Hypotension , exercise intolerance, resting tachycardia, dysphagia, nausea and vomiting (due to gastroparesis), constipation and/or diarrhea (including dumping syndrome), fecal incontinence, urinary retention and/or incontinence, erectile dysfunction and retrograde ejaculation, and decreased vaginal lubrication. Radiculopathiesmost often affect the proximal lumbar (L2 through L4) nerve roots, causing pain, weakness, and atrophy of the lower extremities (diabetic amyotrophy), or the proximal thoracic (T4 through T12) nerve roots, causing abdominal pain (thoracic polyradiculopathy). Cranial neuropathiescause diplopia, ptosis, and anisocoria when they affect the 3rd cranial nerve or motor palsies when they affect the 4th or 6th cranial nerve. cause finger weakness and numbness (median nerve) or foot drop (peroneal nerve). Patients with diabetes are also prone to nerve compression disorders, such as Carpal Tunnel Syndrome . Mononeuropathies can occur in several places simultaneously (mononeuritis multiplex). All tend to affect older patients predominantly and usually abate spontaneously over months; however, nerve compression disorders do not. Diagnosis of symmetric polyneuropathy is by detection of sensory deficits and diminished ankle reflexes. Loss of ability to detect the light touch of a nylon monofilament identifies patients at highest risk of foot ulceration (see figure). Alternatively, a 128-Hz tuning fork can be used to assess vibratory sense on the dorsum of the first toe. Electromyography (EMG) and Nerve Conduction Studies may be needed to evaluate all forms of neuropathy and are sometimes used to exclude other causes of neuropathic symptoms, such as radiculopathy not caused by diabetes and carpal tunnel syndrome. Management of neuropathy involves a multidimensional approach including glycemic control, regular foot care, and management of pain. Strict glycemic control may lessen neuropathy. Treatments to relieve symptoms include topicalcapsaicincream, tricyclic antidepressants (eg,amitriptyline), serotonin-norepinephrinereuptake inhibitors (eg,duloxetine), and antiseizure medications (eg,pregabalin,gabapentin). Patients with sensory loss should examine their feet daily to detect minor foot trauma and prevent it from progressing to limb-threatening infection. A 10-g monofilament esthesiometer is touched to specific sites on each foot and is pushed until it bends. This test provides a constant, reproducible pressure stimulus (usually a 10-g force), which can be used to monitor change in sensation over time. Both feet are tested, and presence (+) or absence (−) of sensation at each site is recorded. 