Detecting And Treating Patients With Diabetic Autonomic Neuropathy

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A 56-year-old Hispanic female with diabetes underwent an open partial first ray amputation and lower extremity angioplasties. No response was noticed three days after surgery even with good wound care.
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Author(s): 
By Damieon Brown, DPM and Javier La Fontaine, DPM

Her past medical history includes NIDDM for eight years, hypertension, hyperlipidemia, coronary artery disease, myocardial infarction in 1995, nephropathy and retinopathy. Her current medications include metformin, glipizide, enalapril and Toprol XL. She had smoked for 40 years but quit in 1995. She denied any alcohol consumption.
Upon a physical examination, we found that the obese patient had a palpable dorsalis pedis pulse but a barely palpable posterior tibial pulse in both feet. Her capillary filling time was less than three seconds. She also demonstrated a loss of protective sensation to 10 sites in both feet. We noted dry, xerotic skin in the lower extremities and no pedal hair.
Her puncture wound was on the plantar aspect of her left hallux with erythema extending through the first interspace and a full thickness dry eschar in the lateral aspect of the hallux. A laboratory evaluation was within normal limits. Radiographs revealed no foreign body nor signs of osteomyelitis.
Since there were concerns about her blood flow status, we ordered non-invasive studies. Significant findings included a left ABI of .91, a TBI of .43 and biphasic waveforms to the anterior tibial artery and posterior tibial artery. Transcutaneous oximetry at the midfoot level demonstrated a response from 1 to 23 mmHg to 100 percent oxygen challenge for 10 minutes. Vascular surgery recommended that the patient should heal.
We first performed an open partial first ray amputation, which demonstrated a local abscess at the first interspace with a significant soft tissue loss. However, five days after the surgery, the wound did not progress. After again consulting the vascular team, we performed an angiogram. The angiogram revealed iliac disease and 60 percent stenosis of the anterior tibial and posterior tibial artery of the left lower extremity. The vascular team decided to stent the lesion in the iliac artery and monitor the wound.
Five days later, the wound still demonstrated no improvement. At this point, the vascular team decided to perform an angioplasty at the level of the anterior tibial artery and posterior tibial artery. Again, the team performed transcutaneous oximetry, which demonstrated an increase from 33 to 54 mmHg at the midfoot level. Arterial Doppler waveforms improved to a triphasic signal. The vascular surgery team said they had achieved optimal blood flow. The team continued appropriate local wound care with the patient on an outpatient basis.
One month later, the patient was readmitted to the hospital for a non-healing wound with cellulitis. However, when the team employed hyperbaric oxygen therapy, they were able to heal the patient’s wound.
This case demonstrates the fact that this patient had a minimal peripheral arterial occlusive disease. Even after the improvement of blood flow after interventional angioplasties, the patient still needed adjunctive therapy, specifically hyperbaric oxygen therapy, to achieve complete healing. It demonstrates that tissue hypoxia was the etiology in this problem wound, not diminished blood flow.

Final Notes
Dysfunction from autonomic neuropathy can be a complicating factor in the diabetic population. Identifying the patient with diabetic autonomic neuropathy will help clinicians assess the spectrum of the disease and subsequently place this patient in the “at risk” category, knowing that he or she could be at risk for ulcerations, gangrene or Charcot arthropathy.

Dr. La Fontaine is an Assistant Professor in the Department of Orthopedics/Podiatry at the University of Texas Health Science Center. Dr. Brown is a first-year resident in the aforementioned department at the University of Texas Health Science Center.

Dr. Steinberg (pictured) is an Assistant Professor in the Department of Orthopaedics/Podiatry Service at the University of Texas Health Science Center.




References:

References

1. Vinik AI, Maser RE, Mitchell BD, Freeman R: Diabetic Autonomic Neuropathy. Diabetes Care, Vol. 26(5), 1553-1579, May 2003.

2. Tananberg RJ, Schumer MP, Greene DA, Pfeifer MA: The Diabetic Foot. Mosby 6th ED., 33-64, Philadelphia 2001.

3. Armstrong DJ, Lavery LA, Harkless LB: Treatment-based classification system for assessment and care of diabetic feet. JAPMA 86: 311-316, 1996.

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