Brachial and lumbosacral plexus injuries after radiation

Introduction Radiotherapy is the best treatment option for breast, neck, testicular and lymphoma, and it is also the most likely to cause brachial plexus and lumbosacral injuries after radiation. Radioactive peripheral neuropathy often has a certain period of incubation, usually months to 2 years, and can last for more than 10 years. The disease is usually slow onset, and a few cases can suddenly start on days or months after receiving radiotherapy. Most patients with radiation brachial plexus are first characterized by decreased finger sensation or paresthesia, and some can have both hands and fingers. As the disease progresses, the affected limb pain may gradually appear. A small number of patients have started with sudden movement disorders.

Cause

(1) Causes of the disease

Radiation therapy is the leading cause of radiation-induced peripheral neuropathy. Other diseases can also be caused by improper protection or accidental exposure to waste radioactive sources.

(two) pathogenesis

The occurrence of radiation-induced peripheral neuropathy is associated with radiation-induced treatment of connective tissue fibrosis around the nerve trunk or nerve plexus. It has been confirmed that after 22 months of high-dose radiation therapy, the autopsy pathological observation showed that there was obvious fibrosis around the brachial plexus. Microscopic examination showed that the proximal nerve of the fibrotic area was relatively intact, and the fibrotic part of the nerve was outside. The membrane is thickened, the myelin is lost, and the nerve fibers are replaced by fibrous connective tissue. The distal median nerve of the fibrotic part also has extensive and obvious demyelination, nerve fiber atrophy, and partial replacement by fibrous tissue. Another patient who received low-dose radiation therapy for 12 months had only mild neurological symptoms in the clinic. Post-mortem autopsy revealed fibrosis only in front of the brachial plexus, and the nerves were almost unaffected, except for two small arms near the forearm of the armpit. The nerves were slightly demyelinated and fibrotic, and the remaining axons and myelin were normal. It can be seen that the dose of radiation therapy and the degree of pathological findings of nerve plexus fibrosis are completely consistent with clinical manifestations.

an examination

Related inspection

Spinal muscle strength test of toe long flexor muscle strength test

1, the physical examination showed that the motor sensation was abnormal, and the sputum reflex was weakened. The upper brachial plexus and the lower brachial plexus are often involved at the same time. Very few patients involve the phrenic nerve, causing diaphragmatic paralysis.

2. Neuroelectrophysiological examination showed denervation potential, fibrillation potential and myokymic discharge. Both motor and sensory nerve conduction velocity were slowed down, and motor block was detected between the cervical spinal cord and the clavicle. The somatosensory evoked potential showed N9 disappearing.

Differential diagnosis

Brachial plexus MRI can identify whether a breast cancer or a neck tumor recurs to invade the nerve or a post-radiation neuropathy. Skull base MRI can identify nasopharyngeal tumor recurrence and radioactive glossopharyngeal nerve injury. King reported 17 patients with glossopharyngeal nerve spasm within 2.5 years after radiotherapy for nasopharyngeal tumors. MRI revealed 14 cases of radiation damage, manifested as extensive fibrosis along the glossopharyngeal nerve pathway, involving the pharyngeal neural tube and carotid sheath . 2 cases were tumor recurrence, and 1 case was tumor recurrence with radioactive injury.

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