Radiation myelopathy in over-irradiated patients: MR imaging findings

Abstract

The objective of this work is to report the MRI findings in patients with radiation myelopathy due to accidental local over-irradiation syndrome. Eight patients (seven males and one female) were suffering from over-irradiation syndrome as a result of treatments from a malfunctioning linear electron accelerator. The mean accidental estimated dose was 136 Gy delivered to the "open-neck" (seven cases) and to the thoracic wall (one case), during a mean of 5.4 sessions (range 1-9 sessions). Paresthesia and weakness in the upper extremities were the earliest symptoms (87.5 %), with evolution to paralysis in all patients. No patient is alive (mean survival time 64 days). In all cases MRI was negative for neurologic lesions in the acute phase ( < 90 days from irradiation; Radiation Therapy Oncology Group scoring system). Late signs of radiation myelitis manifested as high-intensity signals on T2-weighted images in three patients, and as Gd-DTPA enhancement of T1-weighted images in one case. Autopsies performed on four patients who died in acute phase showed morphologic alterations in white matter: edema in 75 %, and necrosis and glial reaction as well as obliterative vasculitis in all cases. In cases of over-irradiation, MRI may be normal in acute phase even if the patients have severe neurologic deficit, as positive MRI findings appear only in delayed radiation myelitis.

Autopsy verifies demyelination and lack of vascular damage in partially reversible radiation myelopathy

“…It is safe to state that the signs accompanying this disease and detected by MRI, such as oedema in the acute disease, gadolinium enhancement in the subacute period and atrophy in the chronic phase, are aspecific. 18 12 In an attempt to interpret the clinical peculiarities in the case history of our patient, together with the results of the PET imaging and histopathology, we refer first of all to the gradual recovery of the functions lost because of radiotherapy. It is generally accepted that remyelination allows the restoration of saltatory conduction and the regaining of the normal function lost during demyelination.…”

“…18,22 The latency period in these patients was very short (around 1 month) and the disease had a very fast progression. The vascular injuries developed exceptionally quickly, and all patients died within 3 months, before the development of significant demyelination.…”

“…[4][5][6]11 Tables 1 and 2 present data on 17 cases of Type 1 lesions and 10 cases of Type 2 injuries, collected from the English literature. [4][5][6]9,12,[17][18][19][20][21][22][23][24][25][26] The Type 2 lesions were further subclassified on the basis of the delivered dose, as cases with doses in the conventional therapeutic range (six cases) and those with an accidental, extremely high overdosage (four cases).…”

Characterization of late radiation effects in the rat thoracolumbar spinal cord by MR imaging using USPIO

“…Furthermore, several clinical investigations on spinal cord complications of irradiation [9][10][11][12][13][14] and one study on accidental over-irradiation [15] have been published. These publications reported spinal cord swelling or atrophy depending on the time between radiotherapy and imaging.…”

Clinical Outcomes After Reirradiation of Paraspinal Tumors

“…14 Even later, there may be atrophy with no signal abnormality. 15 Treatment of radiation-induced myelopathy consists of corticosteroids and palliative medication as needed for pain. Recently there has been investigation into the use of hyperbaric oxygen, which has some promising initial results.…”