Introduction
Diabetic amyotrophy (DA) also known as, diabetic lumbosacral radiculoplexus neuropathy (DLRPN), has been considered to be an often asymmetric, relatively acute, painful neuropathy dominated by proximal lower-limb muscle weakness. Painless DA, considered as a variant of DLRPN, is characterized by subacute or chronic and more symmetric distal lower limbs weakness. However, we experienced a patient who presented with acute pattern of painless DA. Appropriate treatment in early stage is important and expected to reduce permanent disability. We report a case of painless DA showing a rapid recovery through early steroid treatment.
Case report:
A 28-year-old man with diabetes mellitus (DM) type 1 over 10 years ago, admitted to our hospital because of progressive lower limbs weakness, difficulty climbing stairs over 2 months. A week after hospitalization, he felt sudden severe lower extremities weakness without pain and accompanied by mild weakness of upper extremities. Physical examination revealed upper limbs- MRC grade 4/5, lower limbs- MRC grade 1~2/5, and stocking pattern of sensory impairment existed. Tendon reflexes of the ankles and knees were absent. Pathologic reflexes were negative. Laboratory findings such as CBC, ESR and CRP level were within normal limits, and ANCA test was negative. Nerve conduction study demonstrated no response in lower limb sensory and motor nerves, except for relatively reduced motor amplitude of left femoral nerve. Electromyography (EMG) showed denervation potential in lower limbs and lumbar paraspinal muscles. These findings were compatible with bilateral lumbosacral radiculoplexopathy with underlying length dependent pattern diabetic polyneuropathy (Table 1a, 1b).
Pelvic plexus MRI showed diffuse enlargement and high signal intensity of the femoral, genitofemoral and sciatic nerves and lumbosacral trunk and sacral plexus, symmetrically (Fig. 1). We started intravenous high dose steroid therapy. The weakness was recovered dramatically (MRC grade of 4/5 bilateral) only after a week of steroid therapy. After 1 month, he can walk without assistance, and berg balance scale’s score was elevated from 14 to 36.
Conclusion
DLRPN showed a spectrum of disorders exhibiting several clinical presentations. The painless DLRPN has been known to be a slowly progressive course. However, we experienced a case with acute exacerbation form of the painless DLRPN. The early recognition and following an immunomodulatory therapy would be a good choice for the neurologic improvement.
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*: Abnormal data, Lat: latency, Amp: amplitude, CV: conduction velocity, Amplitude (mV) in motor conduction study, Amplitude (uV) in sensory conduction study, MUPs: motor unit potentials, Fibs: fibrillation potentials, PSW: positive sharp waves, Poly: polyphasia, Amp: amplitude, Dur: duration, R: recruitment, S: silent, LFCN: Lateral femoral cutaneous nerve, NE: Not evoked, LA: large amplitude, LD: long duration, VM: Vastus medialis, TA: Tibialis anterior, PL: Peroneus longus, GCM: Gastrocnemius medial head, PVM: paravertebral muscle
*: Abnormal data, Lat: latency, Amp: amplitude, CV: conduction velocity, Amplitude (mV) in motor conduction study, Amplitude (uV) in sensory conduction study, MUPs: motor unit potentials, Fibs: fibrillation potentials, PSW: positive sharp waves, Poly: polyphasia, Amp: amplitude, Dur: duration, R: recruitment, S: silent, LFCN: Lateral femoral cutaneous nerve, NE: Not evoked, LA: large amplitude, LD: long duration, VM: Vastus medialis, TA: Tibialis anterior, PL: Peroneus longus, GCM: Gastrocnemius medial head, PVM: paravertebral muscle
Fig 1. The coronal proton density fat saturated pelvic plexus MRI showed a diffuse enlargement and increased signal intensity at lumbosacral trunk and sacral plexus, sciatic nerve, both, symmetrically
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