Diabetes Mellitus is a chronic disease affecting 246 million peopleworldwide, according to the International Diabetes Federation.Due to the growing problem of obesity and associated Type 2Diabetes, incidence is expected to double by the year 2030. Diabetesrequires continuous medical care and patient education to preventacute complication and decrease risk of long–term complications.Diabetic neuropathy (DN) is one of the most common complicationsof diabetes and can occur at any stage of the disease, affecting50–70% of all patients.
There are many theories as to the cause of chronic neuropathy indiabetics; however it is still unclear as to the mechanism of nerve injuryand subsequent pain. Likely it is a complex cascade of metabolicand ischemic factors. In any patient with presumed diabetic neuropathy,other causes of neuropathy should also be considered includingexcessive alcohol intake, vitamin B12 deficiency, hypothyroidism,familial forms of neuropathy, renalfailure, malignancy, and neurotoxic drugs.
All patients with diabetes should be screenedfor DN at the time of diagnosis and annually thereafter.Screening tests include pinprick sensation,temperature and vibration perception, a 10–gmonofilament pressure sensation on the distalplantar side of both big toes, and ankle reflexes. Usinga combination of one or more of these tests hasmore than 87% sensitivity in detecting neuropathy.Early recognition of DN is important due to substantialmorbidity and mortality of untreated neuropathies.Screening can recognize patients whoare at risk of insensate injury to the feet (as muchas 50% of DN may be asymptomatic). Men are affectedmore than women and there is a direct correlationwith poor diabetic control and increasedrisk of neuropathy.
Neuropathies can be classified as peripheral,proximal, focal or autonomic. Peripheral neuropathy is the most commonform and causes pain and numbness in distal extremities. Symptomsare more common in the feet and legs than hands and arms.Proximal neuropathy leads to pain and weakness of the thighs, hipsand buttocks. Focal neuropathies (cranial nerves, lumbar/cervical radiculopathy)secondary to diabetes are rare and focal symptoms warrantfurther evaluation with imaging studies or nerve biopsy. Clinicalmanifestations of autonomic neuropathy include tachycardia, orthostatichypotension, constipation, erectile dysfunction and sudomotorchanges. Autonomic neuropathy causes increased risk of myocardialischemia and mortality.
Diagnosis is largely based on history and physical examination.Electromyography and nerve conduction studies are occasionallyused to determine extent of nerve injury, although these tests are rarelynecessary to diagnose diabetic neuropathy. Symptoms of DN varydepending on nerves involved and can include numbness, tingling,pain, weakness, GI disturbance, erectile dysfunction and dizziness.Pain is a common feature of diabetic neuropathy, affecting 10–20% ofall diabetics. Symptoms are generally described as burning or throbbingand usually start in the feet, progressing proximally over time.
The first and most important step in treatment of DN is optimizingglucose control. Observational studies have shown neuropathicsymptoms improve with tight glycemic management. There are a variety of pharmacologic and non–pharmacologic treatments available forthe treatment of pain from DN. NSAIDs are helpful for some patients,however they can cause stomach irritation and renal damage withlong–term usage. Capsaicin is a topical cream that relieves pain by reducingthe level of substance P – an important mediator in pain pathways.Tricyclic antidepressants (TCA’s: amitriptyline, nortriptyline)have been widely studied and shown to be effective for neuropathicpain states, however they tend to have troublesome side effects such asdrowsiness, dry mouth and cardiovascular disturbances. Duloxetine isa serotonin/ norepinephrine reuptake inhibitor antidepressant with amore favorable side effect profile than TCA’s. Several anticonvulsantdrugs are used in the treatment of neuropathic pain, including gabapentinand pregabalin. Anticonvulsants work by reducing the abnormalfiring of nerve cells. Opioid medications are not as effective for neuropathicpain syndromes such as DN, although in severe refractory casesthey may have a role. Duloxetine and pregabalin areFDA–approved specifically for the treatment of painfuldiabetic neuropathy. Some patients also experiencerelief with non–pharmacologic therapies such ashypnosis, relaxation training, biofeedback, acupuncture,TENS therapy and spinal cord stimulation.
Foot care is especially important in the diabeticpatient with neuropathy. Loss of sensation in the feetleads to sores and injuries that often go unnoticed,leading to infection. Half of all lower extremity amputationsoccur in diabetics, and it is estimated half ofthese could be prevented with careful foot care. Carefulfoot care includes daily self exams, daily cleaning,nail filing, wearing protective shoes and annual comprehensivefoot evaluations.
Treatment of the underlying nerve damage causingneuropathy is not currently available, althoughoptimizing glycemic control may slow progression ofneuronal damage. Unrecognized diabetic neuropathycan cause severe and permanent damage; therefore it is of utmost importanceto evaluate diabetics for this complication early and often.With proper treatment and vigilance, patients with DN can minimizetheir chances of complications. Optimal glycemic control diminishesthe risk of developing a disabling peripheral neuropathy. Prevention ofdiabetic neuropathy and its complications remains the best strategy.
Diabetic neuropathy continues to be a difficult problem for physiciansto address, and the pain from DN can cause significant distressfor patients. There are many options to treat this condition includingconservative measures, patient education and specialty care.Scott Worrich, MD is a Diplomate of the American Board of Anesthesiologywith a subspecialty certification in Pain Management. Heearned his medical degree from the University of Texas Health ScienceCenter at San Antonio and completed an Anesthesiology residency atthe Penn State Hershey Medical Center prior to returning to San Antoniofor a post–doctorate Fellowship in Pain Medicine from the Universityof Texas Health Science Center.
His interests include cancer pain, neck and back pain, neuromodulation(spinal cord stimulation) and neuropathic pain syndromes. Hebelieves in improving his patients’ quality of life through a multimodalapproach to pain management. He practices with Consultants in PainMedicine in San Antonio and Boerne and can be contacted for an appointmentat 210.447.6491.
