An Incidental Finding

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CHALLENGING CASE

History

A 67-year-old woman comes to the urgent care because she fell in the shower three days ago. She insists that she doesn’t have any symptoms and she says that she slipped on soap. She has not had any headaches or changes in vision, sensory, or motor function before or after she fell.

She had not been planning on coming in for a medical evaluation, but when her son stopped by to visit her at her home, he noticed a bruise on her forehead. When she told him about her falling episode that occurred in the shower, her son wanted her to be evaluated and brought her to urgent care.

She has had osteoarthritis for about 20 years. She lives by herself. She used to work as a cashier and retired three years ago. She drives, and she goes out to do errands about two times a week; other than that, she rarely gets out. She is not physically active. She used to go to church but stopped around the time she retired. She used to smoke one pack of cigarettes per day, and she quit about 10 years ago. She used to drink a few times per year at weddings and no longer drinks at all.

Physical examination

She is awake and alert and oriented x 3. She has a large bruise on the left side of her forehead and what appears to be a clean, healing, superficial wound on her head without any deep cuts. Her skin appears normal. Her blood pressure is 140/75 and her heart rate and rhythm are regular, without any murmurs. She has no carotid bruits. Breath sounds are clear and breathing rate is normal. She has a soft abdomen with normal bowel sounds, no lesions or tenderness. Her pulses are diminished in her lower extremities and normal in her upper extremities.

She has mildly slurred speech. Her language and comprehension are normal. She does not demonstrate any facial asymmetry. Her extra ocular movements are intact with no nystagmus. Her pupils are equal, round and reactive to light. There are no signs of bleeding or trauma to her eyes. Her fundoscopic examination is normal and her hearing examination is normal with no signs of trauma to her ears. She has decreased sensation to light touch, pinprick, temperature and vibration of the left foot and leg. She has normal sensation of bilateral upper extremities. She has brisk reflexes of the right lower extremity and decreased reflexes of the left lower extremity and both upper extremities.

Her strength is 4/5 in the right lower extremity and mildly decreased in her left lower extremity. She has normal strength in bilateral upper extremities. Her coordination is slow but accurate. Her gait is normal when walking. Romberg is positive (she is unable to stand straight with both feet together) and she is off balance when asked to walk heel-to-toe.

Diagnostic tests

A brain CT scan showed a 5 cm subdural hematoma of the left frontal lobe. Her blood glucose level was 210 and her glycosylated hemoglobin was 6.5. She had nerve conduction velocity (NCV) and needle electromyography (EMG) studies, which showed decreased amplitude in all 4 limbs as well as slowed velocity in the left lower extremity.

What's your diagnosis?

Diagnosis: Diabetic Neuropathy

This patient has several abnormalities on her physical examination, which can be misleading.¹ Falling is a very common cause for a medical visit, particularly among older patients. In this case, the patient appears to have upper motor neuron symptoms, consistent with the left subdural hematoma, which may need to be evacuated. She also has signs of peripheral neuropathy, and, given her blood glucose, glycosylated hemoglobin levels, and EMG/NCV patterns, it is likely diabetic neuropathy.

The patient did not know that she had diabetes. Overall, it sounds like she has what appears to be low energy or a lack of motivation. When patients have these symptoms but do not complain, they may be caused by depression, diabetes, or chronic pain.

Diabetic neuropathy is believed to be produced by micro vascular damage caused by the buildup of glucose and other toxins, which decreases blood supply to the nerves. The sensory loss is usually the earliest sign, and it is typically followed by development of neuropathic pain, motor weakness, and autonomic neuropathy. The nerve damage of diabetic neuropathy begins as axonal damage, and may also involve demyelinating features, particularly later in the course of the illness.

Electromyography (EMG) and nerve conduction velocity (NCV) patterns point to axonal involvement of all four limbs, and demyelinating effects on the left lower extremity. A mixed pattern on electrical studies is typical,² as there is not a reliably diagnostic set of results on EMG/NCV. Electrical studies can identify neuropathy as well as the type of nerve damage, but they do not identify the cause of damage.

In patients with diabetic neuropathy, the medial plantar nerve action potential (NAP) amplitude and dorsal sural nerve amplitude can be expected to decrease compared with controls, but this is not always the case. Some patients have slowed conduction, which is reflective of demyelination in addition to the axonal damage. Nerve biopsy findings may show axonal degeneration, regenerative clusters, and segmental demyelination, but biopsies are also not diagnostic of diabetic neuropathy, nor are they standard in the routine neuropathy workup.

Treatment

In addition to the patient’s subdural hematoma that may need to be surgically evacuated if the blood is not resorbed quickly, this patient likely has non-insulin dependent diabetes. Her diabetes management should start with dietary approaches to glucose control, possibly with medication added if the dietary approach does not work. The neuropathy itself is not treatable, but in some cases, it can slow in progression with optimal blood sugar control.

Take home points

• Patients usually do not complain of symptoms of diabetic neuropathy; it is often an incidental finding, even when it has a clinical impact (eg, a fall)

• Effects of diabetic neuropathy on physical examination can be masked by effects of other neurological conditions, such as slurred speech, right leg weakness, and brisk reflexes caused by the subdural hematoma in the case of this patient

• Electromyography and nerve conduction studies often show changes with diabetic neuropathy, but the changes are not always consistent or diagnostic. Diabetic neuropathy is a clinical diagnosis

References:

1. Maltese G, Tan SV, Bruno E, et al. Peripheral neuropathy in diabetes: it's not always what it looks like. Diabet Med. 2018; 35(10):1457-1459.

2. Petropoulos IN, Ponirakis G, Khan A, et al. Diagnosing Diabetic Neuropathy: Something Old, Something New. Diabetes Metab J. 2018;42:255-269.