Extra and intradural spinal HEmangioblastoma

Hemangioblastomas do sistema nervoso central sao lesoes de baixo grau de malignidade, altamente vascularizadas, que podem se apresentar esporadicamente ou associadas com a doenca de Von Hippel-Lindau. Hemangioblastomas extradurais sao incomuns e os extra e intradurais sao ainda mais raros. Este estudo usa um caso ilustrativo e revisao da literatura para discutir as dificuldades de considerar o diagnostico correto e selecionar a melhor abordagem cirurgica. Um paciente do sexo masculino, branco, com 57 anos de idade apresentou-se com mielopatia e radiculopatia de C5 a direita. As imagens mostraram lesao extra-intradural lobulada, em forma de ampulheta, com alta impregnacao apos contraste, que ocupava o canal vertebral e estreitava o forame intervertebral de C4-C5 a direita. A resseccao total da lesao intradural foi alcancada atraves de abordagem posterior, mas a porcao extradural so pode ser parcialmente removida. Melhora total dos sintomas foi observada apos quatro meses e o tumor residual tem sido seguido clinica e radiologicamente. Embora a impressao pre-operatoria tenha sido de um schwannoma espinal, o exame histopatologico revelou hemangioblastoma grau I, segundo a OMS. Apesar de sua raridade, exames complementares atuais permitem o correto diagnostico pre-operatorio. Isto e essencial para melhor programacao cirurgica, tendo em vista as caracteristicas particulares desta lesao.

The aim of this study is to discuss the difficulties to determine the correct preoperative diagnosis of these lesions and its importance on deciding the best treatment strategy based on a case report and literature review.

ILLUSTRATIVE CASE
A 57 years-old white male presented with a 6 months history of neck pain and 1 month of increasing weakness of the superior limbs, followed by lower left limb paresis, bowel and bladder disturbance.His additional medical history was significant only for hypertension.Physical examination demonstrated myelopathy and C5 radiculopathy characterized by triparesis that was worse in the upper limbs with preserved strength in the lower right limb, increased tone and Babinski signal in his lower extremities as well as deep hyperreflexy, though right biccipital hyporeflexy.On spine CT scans (Figure 1A) a marked widening of the right C4-C5 intervertebral foramen was noted, as well as facets erosion and no hyperostosis.The MRI (Figure 1B  The patient was placed in a right lateral position with the head fixed in the Mayfield and aligned with the vertebral spine.(Figure 3A,B) A straight medial occipito-cervical incision was performed followed by a C3-C4 laminectomy and right C4-C5 foraminotomy and "T" shape durotomy directed to the lesion entry point at the intradural space.The entry point was coagulated and cut to permit the total resection of the intradural lesion.The surgical finding consisted of a firm and high-vascularized extradural lesion that made the intervertebral foramen and the C4 joint surface very thin and crossed the dura at the level of C4.The intradural lesion was soft, resembling a sponge, attached to the dura and supplied by anomalous vessels.Total resection of the intradural part of the lesion could be achieved, but the extradural part was removed partially.The lateral dural opening was occluded with a muscle patch and sutured to the dura.The histopathological examination revealed an haemangioblastoma -WHO grade I (Figure 4A,B,C,D,F).The patient improved completely and was already asymptomatic 4 month after surgery.Postoperative MRI showed remaining lesion extradurally, that has been followed clinically and radiologically for 1 year already.Investigation for Von Hippel-Lindau disease was performed and resulted negative.The brain and the rest of the spinal canal were scanned and no additional tumoral lesion was found.

DISCUSSION
In these rare cases of extra-intradural haemangioblastomas, enlargement of an intervertebral foramen and a dumbbell shape wrongly suggest the preoperative hypothesis of nerve root schwannoma or neurofibroma 1 .Nevertheless, schwannomas that grow with an extension to the intervertebral foramen are not common 16 ; and there are some other different kinds of tumors that may present with this location.Besides these facts, extra-intradural hemanioblastomas are extremely rare 1,9,10,13 .However, with the diagnostic tools nowadays available, even the diagnosis of such an uncommon lesion is possible.On MRI sequences, solid portions of haemangioblastomas generally have high-intensity signal on T2-weighted images, intermediate or low-intensity signal on T1-weighted sequences, and marked enhancement with gadolinium 5,7,10,17-19 .Features suggesting vessels, such as flow-void images, are often visible, especially in large tumors 5 .Angiography confirms the diagnosis of a highly vascularized tumor 4 , thus eliminating the possibility of an arteriovenous mal-formation 17 .The key to preoperative diagnosis in these tumors is their marked enhancement and associated enlarged vessels 20 .Surgery is the treatment of choice for symptomatic haemangioblastomas 1,4,10 , but cervical dumbbell lesions raise the problems of radical resection, vertebral artery control, nerve root preservation, and spine stability 1 .An anterior approach alone through the vertebral body is not adequate, because it cannot reach the extra spinal and foraminal part of the tumor.Barrey et al. 1 defend a lateral approach because it allows control of the distal nerve root and the vertebral artery before resection of the tumor and permits reaching even the intradural part as was showed in their case report.In that case the vertebral artery was firstly tested and sacrificed during surgery, as well as the nerve root, which stimulation resulted no response.
A posterior approach with laminectomy and unilateral facetectomy has been proposed for dumbbell neuromas 21 and was chosen for the present case.The good visualization of the intradural space made it possible to resect the whole intradural part without causing additional injury to the spinal cord.However, the hard visualization of the vertebral artery and no control of the blood supplying vessels before the tumor resection made it impossible to perform a radical resection.Another disadvantage of this approach is that a joint must always be sacrificed 1 .The residual lesion next to the vertebral artery may cause gradual occlusion of this vessel and the possibility of its sacrifice in a likely reoperation.
If the posterior surgical approach is chosen, preoperative embolization or even vertebral artery occlusion may be considered after balloon occlusion test in cases of haemangioblastomas to decrease tumoral blood supply and facilitate surgical resection 14 .In lateral approaches, the vertebral artery will be visible before reaching the tumor, and the vascular control could be performed at the surgical act 1 , although balloon occlusion testing before surgery is mandatory.

CONSIDERACIONES FINALES
Despite their rarity, current complementary exams allow considering the diagnosis of haemangioblastoma preoperatively.That is essential to a better surgical setup as these lesions have a great propensity for bleeding.
and 2A,B,C) showed a lobulated, dumbbell shaped, extra-intradural lesion that was markedly enhanced after gadolinium injection.The lesion occupied the spinal canal and the C4-C5 intervertebral foramen compressing and displacing the spinal cord medially and posteriorly.The extra-spinal component came into contact with the vertebral artery, which was slightly displaced medially and anteriorly.Flow-void signals were retrospectively observed inside and around the tumoral mass, suggesting a high-vascularized tumor.Schwannoma and malignant tumors were considered as preoperative diagnosis.

Figure 1 .
Figure 1.Spine CT (A) showing a marked widening of the right C4-C5 intervertebral foramen and erosion of facets.Axial T1-weighted MRI after gadolinium injection (B) showing a dumbbell shaped extra-intradural lesion occupying the intervertebral forame and displacing the spinal cord to the opposite site and posteriorly.

Figure 2 .
Figure 2. MRI sagital images showing a tumoral lesion at C4-C5 level isointense to the spinal cord at T1-weighted (A), with marked enhancement after gadolinium injection (B) and with heterogeneous signal on T2 weighted (C).Low signals in T2-weighted are compatible with enlarged vessels.The lesion is located extramedulary and displaces the spinal cord posteriorly.

Figure 3 .
Figure 3.After C3-C4 laminectomy, (A) "T" shape durotomy directed to the point where the lesion crossed the dura is shown.The right dentate ligament was sectioned and pulled to the left side.This part of the tumor resembled a venous aneurysm and was supplied by anomalous vessels.(B) Total resection of the intradural lesion after coagulation of the dura was performed.