Increased metabolic activity in the spinal cord of patients with long-standing Lhermitte's sign.
OBJECTIVE
To investigate the pathophysiology of the radiation-induced, chronic Lhermitte's sign (LS) on the basis of long-standing case histories with partial functional recovery.


METHODS
As radiotherapy in two nasopharyngeal cancer patients, a biologically effective dose (BED) of 103.8 Gy(2) (case 1) and 94.8 Gy(2) (case 2) was delivered to the cervical spinal cord. Neurologic signs relating to the irradiated spinal cord segments developed after 2 months (case 1) and 5 years (case 2), with radiation-induced damage equivalent to grade 3 (case 1) and grade 2 (case 2) toxicity (Common Toxicity Criteria, Version 2.0). The clinical status improved to grade 2 (case 1) and grade 1 (case 2). Positron emission tomography (PET) and fibroblast clonogen assay were applied 25 and 7 years postirradiation, respectively, to characterize this rare clinical picture.


RESULTS
PET demonstrated increased [(18)F]fluorodeoxyglucose (FDG) accumulation and [(15)O]butanol perfusion, but negligible [(11)C]methionine uptake in the irradiated spinal cord segments in both patients. In clonogenic assays, fibroblasts from case 1 displayed much higher radiation sensitivity than in healthy controls, while in case 2 the fibroblasts sensitivity was normal.


CONCLUSIONS
These data suggests a close direct relationship between regional perfusion and metabolism of the spinal cord, similarly as in the brain. The postirradiation recovery may be related to energy-demanding conduction, explaining the increased metabolism and perfusion. The increased radiosensitivity and higher spinal cord BED may have contributed to the more severe sequelae in case 1.
Esik
Olga
O
Department of Oncotherapy, Semmelweis University, Budapest, Hungary. esik@oncol.hu
Csere
Tibor
T
Stefanits
Klára
K
Szakáll
Szabolcs
S
Lengyel
Zsolt
Z
Sáfrány
Géza
G
Vönöczky
Katalin
K
Lengyel
Erzsébet
E
Olajos
Judit
J
Bajzik
Gábor
G
Trón
Lajos
L
D000328:Adult; D005260:Female; D005347:Fibroblasts / Q000528:radiation effects; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006689:Hodgkin Disease / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008715:Methionine / Q000378:metabolism; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology*; D011836:Radiation Tolerance; D019275:Radiopharmaceuticals; D011878:Radiotherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D013116:Spinal Cord / Q000378:metabolism* / Q000528:radiation effects*; D013118:Spinal Cord Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology*; D013997:Time Factors; D014055:Tomography, Emission-Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008715:Methionine