Introduction

Central nervous system (CNS) cavernomas are rare vascular malformations consisting of closely packed large sinusoid-like vascular channels with little or no intervening nervous tissue. They can occur anywhere in the CNS, but they favor cerebral hemisphere.1, 2, 3, 4 In the spine, cavernomas are found far more frequently in the vertebral bodies and, when involve intradural space, they occur primarily within the spinal cord.5, 6, 7 Intradural-extramedullary location is very rare, with only 23 cases reported in the literature accessible to us by Medline Research.8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27

We describe a case of cavernoma located within the boundaries of a lumbar nervous root and we discuss its clinical, radiological, and surgical findings.

Case report

A 71-year-old man presented to our institution with low-back pain radiating into the left leg. The pain was exacerbated by the supine position.

On physical examination, the patient was found to have hypoesthesia in the left L4 dermatome and absence of the rotuleus reflex.

Lumbar MRI showed a left sided intradural-extramedullary nodular mass at the L3 level. The lesion appeared slightly hyperintense on T1- weighted images without contrast enhancement and hypointense on T2-weighted images (Figure 1a–c).

Figure 1
figure 1

Lumbar MRI shows a nodular mass at the L3 level. The lesion is slightly hyperintense on T1-weighted images (a) without contrast enhancement (b) and hypointense on T2-weighted images (c)

Full size image

An L3 bilateral laminectomy was performed and the dura was opened under microscopic magnification. A reddish lesion was identified incorporated into one nerve root of the cauda equina (Figure 2a and b).

Figure 2
figure 2

Intraoperative view: the dura has been opened; the arrow indicates the angioma included in a nerve root (a). The angioma has been removed; the arrow indicates the root stamp (b)

Full size image

Histopathological examination revealed typical features of a cavernous angioma within the sheath of a spinal nerve and presence of nervous radicula peripherally to the vascular malformation (Figure 3a–d).

Figure 3
figure 3

Thin-walled multiple vascular spaces of different diameter. H&E, 2.5 × (a). A large nerve appears at a margin of the lesion. H&E, 2.5 × (b). In the inset (c), a higher magnification of (b) evidences small nerve fibers compressed by hamartomatous vessels and the broader peripherical nervous component. H&E, 10 × . Staining of nerves by immunohistochemistry for protein S-100 in the same field shown in Figure 2. PAP method, 2.5 × (d). Higher magnification evidences nerve fibers outside the lesion and entrapped in the wall of hamartomatous vessels. PAP method, S-100 protein, 10 × (e)

Full size image

The postoperative period was uneventful and the lumbosciatalgia resolved after operation. One year after surgery, the patient was healthy.

Discussion

Cavernous angioma has been described occurring throughout the entire CNS.1, 2, 3, 4, 6, 15 The most common location of these vascular malformations is the supratentorial cerebral parenchyma. Cauda equina nerve root is a very rare location.4, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26 Pagni et al15 reviewed all intradural cavernous angioma of the spine described in the literature. They concluded that subdural extramedullary cavernous angiomas are the most rare of the cavernomas with only 10 cases documented between 1903 and 1990. Although these vascular malformations are being discovered most frequently because of the widespread use of MRI, they remain still uncommon lesions. A Medline search identified just 24 cases, including the present case (Table 1).8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27

Table 1 Surgically treated spinal intradural-extramedullary cavernous angioma
Full size table

The patients are in their third to seventh decades of life. The most common age at diagnosis is during the third decade. There is a male predominance (M:F ratio 2:1); and the lesions are mostly located in the lumbar region (13 cases – 54%), followed by lower thoracic (seven cases – 29%), cervical region (three cases – 12%), and thoraco-lumbar passage (one case – 4%). Low-back pain and radiculopathy are the main symptoms associated or not with motor deficit or neurologic symptoms secondary to spinal cord compression. However, 37% of patients developed a subarachnoid hemorrhage with acute onset of symptomatology. More rarely (12%), symptoms of intracranial hypertension caused by hydrocephalus have been found.

The preoperative radiological diagnosis of intraroot cavernous angioma is quite difficult, probably because of the rarity of this lesion.

Cavernous angiomas are lesions angiographycally occult, but are easily diagnosed by MRI. MRI is the imaging modality of choice.5, 29 The typical MRI features are those of a well-defined lesion with mixed signal intensity on both T1- and T2-weighted images. They are often surrounded by a hypointense ring on T2-weighted images owing to hemosiderin deposition.8 Enhancement with Gadolinium is variable.28 In the present case, we found no significant contrast enhancement in the cavernous angioma, probably because the intralesional blood flow was too low.

The treatment of choice is surgical removal. The most frequent surgical finding is that the lesion adheres to the nerve roots, dura, or spinal cord extending extraphytically.25 In the present case, cavernous angioma was within one spinal root. This finding was confirmed by histological examination that showed the disarrangement of radicles. A similar pattern of growth is reported only in another two cases.15, 26

Histologically, cavernous angioma must be distinguished from capillary hemangioma. Capillary hemangioma consists of a myriad of small vessels of capillary size. Cavernous angioma consists of large, dilated hyaline vascular channels arranged in diffuse patterns. They often show thrombosis, perivascular hemosiderin deposition, and calcifications.4, 29, 30

Most of the cases surgically treated had excellent results, but in patients with severe preoperative neurological deficits, such as sphincter dysfunction, recovery was not complete.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 Total excision was obtained in most of the cases. Subtotal removal was performed only in one case in which the cavernoma tightly adhered to the spinal cord.24 In most cases, the lesion has been removed sparing the nerve root, but sometimes this is not possible because the lesion originates within the nerve root. This occurred in our case. However, our patient had a good recovery, even if it was necessary to cut the nerve root.