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

Background

Thoracic radiculopathy is relatively a rare cause of severe thoracic-abdominal pain in patients with either type I or II diabetes, often with a poor blood sugar control.1–3

Onset can be sudden or subtle, with gradual worsening, and the pain can be associated with hypoaesthesia/dysaesthesia and weight loss. Patients may also complain of abdominal protrusion because of denervation of abdominal wall muscles.3

The absence of clinical and CT/MRI evidence of abdominal mass, of other gastroenterological diseases or radicular tumour compression supports this uncommon diagnosis, of which gastroenterologists and neurologists should be aware.2 3

Therapy has been symptomatic. Outcome may be favourable, but after several months of unresolving pain. Circumstantial evidence supports the potential for an early immunotherapy.3

Here, we report on a diabetic woman with a severe abdominal pain caused by thoracic radiculopathy, which resolved after a few cycles of intravenous immunoglobulins (IVIg) followed by immunosuppression, along with a stringent blood glucose control.

Case presentation

A 30-year-old woman with a 10-year history of insulin-dependent type I diabetes presented with a 2-month history of sharp and burning pain in the lower abdominal right and left quadrants, often associated with extremely annoying pin-prick paraesthesia (figure 1A). She felt very uncomfortable when wearing dresses and when touched. At baseline, on a subjective Numerical Pain Rating Scale (NPRS; 0=no pain–10=worst pain possible, making the patient pass out), she scored 8 out of 10.

Investigations

She had been seen by several gastroenterologists and underwent upper and lower abdominal echography and post-contrast MRI scan did not disclose abnormalities. A gynaecological evaluation was negative. A further thoracic/lumbar post-contrast MRI were also normal. She has a history of poorly controlled insulin-dependent glycaemia, and there was initial neurophysiological evidence of polyneuropathy in the lower limbs.

Neurological examination showed bilateral pin-prick hyperalgesia in T10-T12 dermatomes. Abdominal reflexes were absent. Lower limb reflexes were absent, with normal sensitivity and muscular mass.

She underwent a biochemical and immunological workup, including blood cell count, a large antibody battery, which included antibodies to anti-Hu, anti-Ri, anti-Yo and anti-gangliosides, which were negative.

We did not perform a specific vasculitis workup, but the patient did not show cutaneous signs and/or symptoms of systemic vasculitis. In addition, as a routine analysis, biological assays for inflammation as PCR and erythrocyte sedimentation rate were made, which were within normal range.

Besides her primary therapy with insulin, she was treated with topiramate, lorazepam, duloxetine and gabapentin without much effect on the abdominal pain.

Nerve conduction studies of the peroneal and sural nerves of both legs documented a peripheral sensorimotor neuropathy. Electromyography revealed fibrillation potentials and positive sharp waves in the paraspinal muscles innervated by T10, T11 and T12 roots (figure 1B).

A diagnosis of diabetic thoracic radiculopathy and lower limbs polyneuropathy was made.

Treatment

The patient underwent a strict monitoring of the blood glucose, and she was submitted to three cycles of monthly treatment with IVIg (0.5 g/kg/day for 5 days each cycle).

Outcome and follow-up

A substantial reduction of the abdominal pain was reported by the patient already after the first IVIg (NPRS=4/5), and it further improved over the cycles. However, the pain did not disappear completely (NPRS=3/4). She then started azathioprine at the dose of 50 mg two times a day (1.5 mg/kg/daily), which in a few months led to a complete disappearance of the abdominal pain and sensory symptoms (NPRS=0–1; figure 1C). Blood cell count was normal during azathioprine treatment.

Neurophysiological evaluation of the T10-T12 paraspinal muscles 4 months after azathioprine only revealed minor abnormalities in T12 (figure 1B). Blood glucose and glycated haemoglobin were monitored over the months and maintained within normal range.