EXTRADURAL SPINAL CORD HEMANGIOBLASTOMA : A CASE REPORT AND LITERATURE REVIEW HEMANGIOBLASTOMA EXTRADURAL

Objective: Hemangioblastoma is a rare vascular sporadically occurring CNS tumor that can be associated with von Hippel-Lindau disease. Hemangioblastomas account for 2-6% of all spinal cord neoplasms and rank third among intramedullary space-occupying lesions. Methods: This was the first time in our practice that we had dealt with paravertebral hemangioblastoma with the sandglass growth pattern. The world literature describes only 3 case of a tumor with this growth pattern. Surgical and diagnostic aspects of patient treatment are considered. Results: During the operation, we adhered to the following stages: localization of the feeding vessel and of the poles of the tumor, surface dissection of the tumor, en bloc resection of the tumor, and hemostasis of the tumor cavity. Conclusions: Hemangioblastoma of extradural localization is a very rare pathology. However, when MRI signs characteristic of a vascular lesion are identified, it is necessary to carry out additional examinations, which may include CT perfusion study and, if required, selective angiography. Level of Evidence 5; Case report.


INTRODUCTION
Hemangioblastoma is a rare vascular sporadically occurring CNS tumor that can be associated with von Hippel-Lindau disease.Hemangioblastomas account for 2-6% of all spinal cord neoplasms and rank third among intramedullary space-occupying lesions of the spinal cord.This was the first time in our practice that we had dealt with paravertebral hemangioblastoma with the sandglass growth pattern.The world literature describes only 3 case of a tumor with this growth pattern.

Clinical Case
Patient N, 56 y.o., was admitted to the Burdenko Scientific Research Institute of Neurosurgery on September 3, 2014 with complaints of pain in the lumbosacral region irradiating to the left leg, as well as sensation disorders manifesting as hypostasis on the posterior surface of the left thigh and lower leg.It is follows from the anamnesis that the back pain had disturbed the patient for a long time, gradually intensifying until eventually, the pain syndrome became permanent.Multiple drug therapy courses were used to treat spinal osteochondrosis.No improvements in the patient's state after therapy were noted.Since 2006, the pain has intensified, starting to occur at rest, when sitting and lying down.In August 2013, the pain became particularly intense, and no significant effects of conservative therapy were achieved.In view of this, MRI study of the lumbosacral spine was performed, revealing an extradural space-occupying lesion with paravertebral proliferation at the level of the L4-L5 vertebrae in the left intervertebral foramen (Figure 1).The neoplasm was oval in shape, with dimensions: 16x25x10 mm.Spinal angiography was performed with contrast in the space-occupying lesion vasculature at the L4 vertebra level.The patient was hospitalized in the neurosurgical department nearest to the place of residence for tumor resection.An attempt to resect the tumor failed.Findings of the collected tissue histological study corresponded to ganglioneuroma.

Surgery
The patient was placed in the prone position on the operating table, under complex anesthesia with endotracheal lung ventilation.The level of the tumor localization was determined using an intraoperative O-arm (Medtronic) CT scanner.The images were taken in the lateral and frontal planes in the 2D mode.A paramedian skin incision was performed on the left, a few centimeters from the scar from the previous operation.The tumor was accessed using an operating microscope and a Caspar retractor.The use of this expander helped minimize trauma to the surrounding tissues.Hemilaminectomy was performed on the left at the level of the L4 vertebral arch, using microsurgical instruments and a high-speed Zimmer drill.The 3 x 2 cm prolate orange tumor was visualized.The tumor was located in the intervertebral opening L4-L5 and resembled a neurinoma in form.The extradural part of the L4 root on the left was determined as the growth zone.During detachment of the tumor along the perimeter, a large vessel feeding the tumor was detected.This vessel was coagulated and incised.Ligation was applied to the proximal part of the tumor and the root, after which the tumor and the nerve root were coagulated and excised en bloc (Figure .2).A hemostatic material was placed in the bed of the excised tumor.The wound was then closed by the standard procedure.
In the postsurgical period, regression of the pain syndrome was noted.The patient was activated on the first day after the surgery.Seven days after the operation, the patient was discharged in a satisfactory condition.Histological diagnosis: Hemangioblastoma.In the 3 months after the surgery, a control MRI study was performed (Figure 3).

Histological characteristics of the tumor
Histological examination confirmed the macroscopic diagnosis of hemangioblastoma.The tumor structure consists of two types of cells: stromal cells with an optically empty cytoplasm, and a large number of hemangioblasts (Figure 4).The tumor (Figure 5 -on the left, marked with a red arrow) was surrounded by a thin layer of a fibrous tissue with closely adjoining nervous tissue fragments and ganglion cells congestion (on the right, marked with a green arrow).
During the study, an adjacent nerve trunk was detected, Pluta, R.M. reports the same histological findings (Figure 6). 2

DISCUSSION
Hemangioblastoma of the spinal cord belongs to a class of highly vascularized tumors with predominant intramedullary localization.In our case, the tumor was situated paravertebrally, demonstrated the sandglass growth pattern, and had no connection with the dura mater.We performed a world literature search and found case studies of three patients with a similar localization of spaceoccupying lesions No. 1, 2, 3. Below is the table with these patients' data, clinical status and the surgical treatment outcome (Table 1).

Clinical pattern
In Case Study No.1, an acute onset of the disease was noted with a severe pain syndrome developing for 2 weeks, after which the patient was hospitalized in a neurosurgical hospital.In the remaining Case Studies No. 2 and 3 as well as in the case study of our patient, a long case history was observed lasting from 2 to 20 years.The tumor manifested itself as radiculopathy in the form of a pain syndrome in the lumbosacral spine, irradiating to the leg, accompanied by sensation disorders.In Case Study No. 2, pelvic organ dysfunction was recorded.Such symptoms are possible with any tumor in this location, therefore in the primary examination stage, pelvic organ dysfunction is not a specific criterion for radicular hemangioblastoma.

X-ray study
In Case Studies No.3 and 4 at the preoperative stage, according to the MRI study, a presumptive diagnosis was established: neurogenic tumor -neurinoma (schwannoma) of the spinal root.The patient with von Hippel-Lindau disease had multiple hemangioblastomas of the central nervous system.The authors therefore suggest performing the correct histological diagnosis at the pre-surgical level.Our patient was admitted to the clinic with a diagnosis of gangioneuroma of the L4 root with paravertebral growth, since after the first surgery, a corresponding histological diagnosis was established.
After our analysis of the X-ray data, the following conclusions were made.First, all studies should be enhanced by a contrast agent.Secondly, detection of pathologically enlarged convoluted vessels within the spinal canal around the lesion is a pathognomonic sign of hemangioblastoma.The vessels are best visualized in the T2 mode.Thirdly, a solid component of the tumor has a hypo-or iso-intensive MR signal in the T1 mode, and the cystic cavities have a signal similar to the CSF in the T1 and T2 modes, or a more intense signal in the T2 mode.Identification of at least one of the listed MRI signs suggests a vascular pattern of the tumor, and selective angiography may be indicated.

Peculiarities of extradural hemangioblastoma resection
Extramedullary hemangioblastoma is a sufficiently rare pathology, therefore there is no standard for such tumor resection.We use the following principles for the tumor resection: first, it is necessary to detach the feeding vessel; in hemangioblastomas this vessel is the radicular artery, running parallel to the radix at the level of the tumor location.The second stage is to separate the tumoral poles, while preserving the enlarged drainage veins of the tumor.Manipulation inside the tumor capsule is dangerous due to the possibility of severe bleeding, which is usually difficult to control and can completely obscure the entire field of vision.Hemangioblastomas are encapsulated and can be easily separated from surrounding tissues.After excision of the tumor, a crater is formed -the tumor bed, which is examined to stop bleeding from small vessels.Hemostasis in this situation must be achieved with the help of hemostatic materials, abstaining from use of bipolar coagulation.
This was the first instance, in our practice, of a hemangioblastoma with extradural location.Therefore, we used the microsurgical

Figure 1 .
Figure 1.Hemangioblastoma of the L4 nerve root.A series of MRI scans performed in the sagittal, frontal and axial projections in the T2 mode (A, B, C) showed an extradural, hypo-intensive space-occupying lesion at the level of the L4-L5 vertebrae with hyperintense foci and paravertebral growth to the left of the dumbbell type.In the sagittal projection (A) the intense tumor vasculature is clearly seen, which corresponds to the multiple zones of the hypointense signal in the T2 mode.(red arrow)

Figure 2 .
Figure 2. Stages of the surgery: A and B -detachment and mobilization of a solid part of the tumor, B -ligation of the L4 root tumor cervix, D -excision of the tumor with the root.1-solid part, 2 -L4 root, 3 -root sleeve, 4 -tumor bed.

Figure 3 .
Figure 3.A series of MRI scans done in the sagittal and axial projections in the T2 mode (A, B, C, D) shows the state after radical excision of hemangioblastoma.

Table 1 .
Review of publications describing treatment of radicular hemangioblastomas of the spinal cord.