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This Article Abstract Full Text (PDF) All Versions of this Article: 10/6/1035    most recent 15228517-2008-069v1 Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ducray, F. Articles by Pradat, P.-F. Search for Related Content PubMed PubMed Citation

Postradiation lumbosacral radiculopathy with spinal root cavernomas mimicking carcinomatous meningitis

Service de Neurologie Mazarin (F.D., D.P., M.S., K.H.-X., J.-Y.D.), Service de Neuroradiologie (R.G.), Service de Neuropathologie (K.M.), Service de Neurochirurgie (S.N., P.C.), Fédération de Neurophysiologie Clinique (T.M.), and Fédération des Maladies du Système Nerveux (P.-F.P.), APHP, Groupe hospitalier Pitié-Salpêtrière, Paris; INSERM U711 (F.D., M.S., K.H.-X., J.-Y.D.), Université Pierre et Marie Curie, Paris; and Service d'Oncologie-Radiothérapie, APHP, Hôpital Saint-Louis, Paris (S.D.); France

Address correspondence to Pierre-François Pradat, APHP, Fédération des Maladies du Système Nerveux, Groupe hospitalier Pitié-Salpêtrière, 47-83, Boulevard de l'Hôpital, 75651 Paris, France (pierre-francois.pradat{at}psl.aphp.fr).

	Abstract

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Lumbosacral radiculopathy is a rare complication of radiotherapy and may be challenging to differentiate from diagnosis of a tumor recurrence. We reviewed the records of three patients with a past history of cancer and radiotherapy who were referred for suspicion of carcinomatous meningitis on lumbar MRI, but whose final diagnosis was radiation-induced lumbosacral radiculopathy. The three patients developed a progressive lumbosacral radiculopathy at 20, 13, and 47 years after lumbar radiotherapy delivered for renal cancer, Hodgkin's disease, and a seminoma, respectively. MRI showed a diffuse, nodular enhancement of the cauda equina nerve roots on T1 sequences, suggestive of leptomeningeal metastasis. A slowly progressive clinical course over several years and negative cerebrospinal fluid cytologic analysis ruled out the diagnosis of carcinomatous meningitis. Because of the radiologic findings, a biopsy was performed in two patients. In the first, a biopsy limited to the arachnoid excluded a malignant infiltration. In the second, a biopsy of the enhancing lesions demonstrated spinal root cavernomas. These observations, together with three recent case reports in the literature, delineate a syndrome of "radiationinduced lumbosacral radiculopathy with multiple spinal root cavernomas" that mimics carcinomatous meningitis on MRI. Its diagnosis is important in order to avoid inappropriate treatment and useless or dangerous spinal root biopsies.

Key Words: carcinomatous meningitis • cauda equina • cavernoma • radiotherapy

	Introduction

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Several neurologic syndromes have been described following irradiation of the spinal cord, cauda equina, or lumbosacral plexus. Well-known complications include acute myelopathy, mild transient sensory myelopathy, chronic progressive myelopathy, sensorimotor lumbosacral plexopathy, and lumbosacral radiculopathy, which can present as a lower motor neuron syndrome.^1–4 The differential diagnosis between tumor recurrence and radiation-induced neurologic complication may be challenging.⁵ We report cases of three patients with a history of lumbar irradiation who developed a progressive lumbosacral radiculopathy mimicking meningeal carcinomatosis.

	Case Reports

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Case 1
A 53-year-old man was referred in 1995 for a 4-year history of progressive numbness and proximal weakness of the left lower limb. Significant medical history included a left nephrectomy in 1971 for renal cancer, followed by local radiation therapy. Initial spinal MRI in 1992 showed multiple nodular enhancements of the cauda equina nerve roots. A surgical approach revealed no tumor infiltration, and arachnoid biopsy showed only hyalinized vessels with no cancer cells. On examination in 1995, the patient walked with a cane. Muscle strength was decreased in both legs. Marked amyotrophy and fasciculations were present in the left thigh. Deep tendon reflexes were abolished in the left lower limb. There was a global hypoesthesia in the left L3 and L4 dermatomes and a left saddle hemianesthesia with sexual dysfunction. Lumbar MRI was unchanged (Fig. 1). A T2 and T1 hypersignal was found in the lumbar vertebrae, indicating that they were included in the radiation therapy field. Cervicodorsal and brain MR images were normal. Cerebrospinal fluid (CSF) examination showed two lymphocytes/mm³ and a protein concentration of 1.8 g/l, without carcinomatous cells. Electromyography (EMG) was consistent with involvement of the L4 to S1 nerve roots predominating on the left side. No relapse of the renal carcinoma was found. Systemic screening for other malignancies was negative. Neurologic condition continued to deteriorate progressively, and on last examination in September 2007, the patient was wheelchair dependent. MRI follow-up did not reveal any changes.

View larger version (141K): [in this window] [in a new window]   Fig. 1. Sagittal T2- and T1-weighted MR images of patient 1 demonstrating nodular thickening of cauda equina nerve roots (a, b) with postgadolinium enhancement (c). Increased T2 and T1 signal is present in lumbar vertebral bodies consistent with previous radiotherapy.

View larger version (117K): [in this window] [in a new window]   Fig. 2. Postgadolinium sagittal T1-weighted MR images of patient 2 (a) and patient 3 (b) demonstrating nodular enhancement of cauda equina nerve roots.

View larger version (114K): [in this window] [in a new window]   Fig. 3. Photomicrograph of the biopsy specimen of the spinal root cavernoma from patient 2 demonstrating large (a) and small (b) blood-filled caverns, lined with a single layer of endothelial cells (hematoxylin and eosin staining, x40). Adjacent nerve fibers appear to be compressed by the cavernous malformations (arrows).

Case 3
A 71-year-old man was referred in 2007 for a 12-year history of progressive symmetric distal weakness of the legs. This patient underwent an orchidectomy for a testicular seminoma followed by radiation therapy with mantle and paraaortic irradiation in 1960. Spinal MRI performed in 2004 showed diffuse, nodular enhancement of the cauda equina nerve roots on T1 sequences. A T2 and T1 hypersignal was found in the lumbar vertebrae, indicating that they were included in the radiation therapy field. In 2007, the patient walked with two canes. He presented with a severe diffuse symmetrical weakness of the lower limbs with fasciculations and wasting. Knee and ankle reflexes were abolished. There were no sensory symptoms or sphincter dysfunction. EMG was consistent with purely motor bilateral involvement of the L3 to S1 roots. Lumbar MRI was unchanged (Fig. 2b). Spinal cervicodorsal and brain MR images were both normal. CSF examination was acellular, and the protein concentration was 1.2 g/l.

	Discussion

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Our three patients developed a progressive, radiation-induced lumbosacral radiculopathy with diffuse, nodular enhancement of the cauda equina nerve roots, simulating meningeal carcinomatosis.

Analysis of these patients together with five previously reported cases reveals a common pattern (Table 1).^5–7 The clinical picture was characterized by an insidious onset of neurologic deficits occurring over many years (median, 24 years) after a course of standard radiotherapy encompassing the cauda equina. Patients developed predominantly motor involvement with slowly progressive weakness, hyporeflexia, and amyotrophy. The topography could be monoradicular but was usually polyradicular, either symmetrical or asymmetrical. Sphincter and sensory disturbances were inconstant and mild. Only one patient had back and lower limb pain.⁵ EMG was performed in six of eight patients and demonstrated a pure motor radiculopathy with decreased amplitudes of motor potentials, normal conduction velocities, and normal sensory potentials of the lower extremities in all patients. These clinical and EMG findings are reminiscent of the "postirradiation lower motor neuron syndrome" reported by Bowen et al.¹

On MRI, the lesions were suggestive of meningeal dissemination along the cauda equina with a T1 isointense signal and a diffuse, nodular gadolinium enhancement without hypointense rim on either T2- or T2^* (T2 Star)-weighted MRI.^5–7 Unlike carcinomatous meningitis, however, postcontrast enhancement was faint, and all of the radiologic abnormalities were restricted to the radiation field, as demonstrated by the signal conversion of vertebral bone marrow on both T1- and T2-weighted images.⁸ Furthermore, this ominous radiologic finding was discordant with the slowly progressive clinical course, the repeatedly negative cytologic CSF analyses (despite elevated protein concentration), and the stable MRI over time.

Pathologic examination was done in four of eight patients (two patients from our study and two prior reported cases).^6,7 In patient 1 from the present study, the biopsy was limited to the arachnoid and permitted only exclusion of a malignant infiltration. In the other three patients, including patient 2 from the present study, biopsy of the enhancing lesions demonstrated multiple spinal root cavernomas.^6,7 Interestingly, in the autopsy study of one of their patients with "postirradiation lower motor neuron syndrome," Bowen et al.¹ noticed a collection of abnormal dilated vessels, some of which had thin-walled, abnormally dilated vascular channels compressing adjacent nerve fibers in the cauda equina. The term "cavernoma" was not employed by these authors, but the resemblance with histologic features observed in our patient and in two prior case reports is striking.

Thus, our patients, together with previously reported cases, provide evidence that in some patients, postirradiation lumbosacral radiculopathy is closely linked with multiple spinal root cavernomas (or cavernomatous-like lesions). These features are quite different from the rare spontaneous spinal root cavernomas for which low-back pain is a common presenting symptom, and MRI shows a well-defined, solitary intradural mass with inconstant enhancement.^9–11 They are also different from the features of solitary brain and spinal postirradiation cavernomas, which have the same radiologic features as spontaneous cavernomas.^12–15 Indeed, unlike these cavernomas, postirradiation spinal root cavernomas demonstrate gadolinium enhancement and are not hypointense on T2^*-weighted MR images.

The role of the multiple cavernomas in the pathophysiology of nerve fiber damage remains unsettled. Radiation-induced cavernomas could simply be an epiphenomenon not responsible for nerve fiber damage. On another hand, cavernomas could cause or contribute to nerve damage, as suggested by the pathologic findings in patient 2 and by the autopsy study of Bowen et al.,¹ showing that cavernomas/dilated vessels compressed adjacent nerve fibers in the cauda equina.

In summary, the clinical and MRI features of our patients and previously reported cases delineate a syndrome of postirradiation lumbosacral radiculopathy with multiple spinal root cavernomas. This diagnosis should be considered in patients with a prior history of lumbar radiation therapy, who many years later develop a progressive, usually painless lumbosacral radiculopathy with MRI findings primarily suggestive of carcinomatous meningitis (Fig. 4). The radiologic abnormalities, however, should be restricted to the field of prior radiation therapy. Diagnosis of this syndrome is important in order to avoid inappropriate treatment and useless or dangerous spinal root biopsies. The evolution of this condition is difficult to predict, but in some patients, spontaneous stabilization has been noticed.⁵ Further studies are needed to precisely report the incidence and the natural history of this syndrome.

View larger version (21K): [in this window] [in a new window]   Fig. 4. Proposed diagnosis algorithm. CSF, cerebrospinal fluid.

Received for publication January 30, 2008. Accepted for publication July 22, 2008.

	References

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Yoshino M, Morita A, Shibahara J, Kirino T. Radiation-induced spinal cord cavernous malformation. Case report. J Neurosurg. 2005; 102: 101-104.[Web of Science][Medline]

This Article Abstract Full Text (PDF) All Versions of this Article: 10/6/1035    most recent 15228517-2008-069v1 Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ducray, F. Articles by Pradat, P.-F. Search for Related Content PubMed PubMed Citation

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