Cervical Radiculoplexus Neuropathy

Cervical radiculoplexus neuropathy is a rare, subacute, painful, asymmetric neuropathy of the cervical roots and brachial plexus, with weakness of the shoulder girdle and arm. It is the upper limb counterpart of diabetic lumbosacral radiculoplexus neuropathy, and includes diabetic cervical radiculoplexus neuropathy and a non-diabetic form. Neuralgic amyotrophy is a closely related disorder.

Pathophysiology. Immune mediated microvasculitis of epineurial vessels causes ischaemic injury to roots, plexus trunks and proximal nerves.

Sudden severe pain in the neck, shoulder or arm, worse at night, followed days to weeks later by weakness, wasting and sensory loss in the C5 to T1 distribution, often asymmetric and multifocal. Weight loss may occur. Pain eases as weakness appears. Recovery is slow over 1 to 3 years and often incomplete.

Red flags.

• Progressive weakness over weeks with systemic symptoms or weight loss.
• Horner syndrome or a lung apex lesion.

Electromyography and nerve conduction studies show patchy axonal denervation of several roots and trunks with sparing of paraspinal muscles in some. MRI of the cervical spine and brachial plexus excludes compression, tumour and radiculopathy, and may show nerve enlargement and T2 hyperintensity. Check HbA1c, inflammatory markers, antinuclear antibodies, ANCA and protein electrophoresis. CSF protein may be raised. Nerve biopsy is rarely needed.

Differential diagnosis.

• Cervical radiculopathy and spondylotic myelopathy.
• Neuralgic amyotrophy (idiopathic and hereditary), Pancoast tumour and radiation plexopathy.
• Thoracic outlet syndrome, rotator cuff tear and motor neuron disease.

Glycaemic control. Optimise diabetes without rapid correction.

Immunotherapy. Evidence is limited. Prednisolone 1 mg/kg daily (up to 60 mg) for 5 to 7 days, then a taper over 4 to 8 weeks, or methylprednisolone 1 g IV daily for 3 to 5 days, may relieve pain and speed recovery in early disease. Intravenous immunoglobulin 0.4 g/kg daily for 5 days is an alternative. Monitor glucose.

Pain. Gabapentin 300 mg three times daily, increased to 600 to 1200 mg three times daily (adjust to eGFR), pregabalin 75 to 300 mg twice daily, duloxetine 60 mg daily, or amitriptyline 10 to 75 mg at night. Short term opioids for severe pain.

Rehabilitation. Early physiotherapy to protect the shoulder from subluxation and maintain range of motion, splinting and occupational therapy.

Monitoring. Strength, pain and glycaemic control.

Referral and escalation. Refer to neurology.