Surgery of Angiomas in the Brainstem With a Stress on the Presence of Telangiectasia

II-4. Spinal and Vascular Malformation Other than AVM Surgery of Angiomas in the Brainstem With a Stress on the Presence of Telangiectasia Masashi FUKUI, Toshio MATSUSHIMA, Kiyonobu IKEZAKI, Yoshihiro NATORI, Takanori INAMURA, Shinji OHARA, and Tadao KAWAMURA Department of Neurosurgery, Neurological Institute, Kyushu University Faculty of Medicine, Fukuoka Abstract This report deals with the surgery of angiomas other than arteriovenous malformation in the brainstem. The surgical cases were three cavernomas, two telangiectasias, and two venous malformations. We performed surgery when an angioma bled and the resulting hematoma was situated near the surface of the brainstem or the fourth ventricle. The cases were operated on at the subacute or chronic stages after hemorrhage. Although a magnetic resonance (MR) image showed a subacute or chronic localized hematoma with a low intensity rim, the case was not always a cavernoma, but a telangiectasia. Cavernomas could be totally removed, but telangiectasia could not. In the cases of medullary venous malformation the diagnosis was obtained radiologically, and when the hematoma was large, only hematoma evacuation was performed. In all cases the postoperative Karnofsky scores were improved or unchanged. Postoperative rebleeding in the hematoma cavity continued insidiously in a case of telangiectasia. The abnormal vessels of telangiectasia in the brainstem were preoperatively not visualized by cerebral angiography or MR imaging, but became visualized by enhanced MR imaging after evacuation of hematoma in two cases. It is stressed that an angioma with a hematoma intensity core surrounded by a low intensity rim on MR images is not always a cavernoma, but possibly is a telangiectasia. Key words: telangiectasia, cavernous hemangioma, brainstem, magnetic resonance imaging, surgery Introduction Various forms of angioma occur in the brainstem. McCormick et al.8) examined angiomas of the brainstem and found that (capillary) telangiectasia is the most common one in the pons, though it seldom presents with symptoms and signs. After introduction of magnetic resonance (MR) imaging reports on surgery of angiomas in the brainstem have increased. When MR imaging shows a mass with a core of hematoma intensity surrounded by a low intensity rim on T2-weighted image, it has generally been considered as a ruptured cavernoma. However, there were also cases of telangiectasia among the reports, though its incidence is low. We have experienced seven surgical cases of ruptured angioma in the brainstem, two of which were found to be telangiectasia. We present our surgical experience of angiomas in the brainstem with a stress on the presence of telangiectasia. Subjects and Results Table 1 shows our surgical cases of ruptured angioma other than arteriovenous malformation (AVM) in the brainstem. Out of seven angiomas three were cavernomas, two telangiectasias, and two medullary venous malformations (MVM). We performed surgery when a hematoma was situated near the surface of the brainstem or the fourth ventricle and large enough to cause compression of the surrounding neural structures. The surgical approaches were the midline suboccipital, lateral suboccipital, occipital transtentorial, and pterional or subtemporal depending upon the location of hematoma. Cavernoma could be totally removed in two out of three cases, but the abnormal vessels of telangiectasia were partially removed. In cases of MVM only hematoma removal was performed. Postoperative Karnofsky scores were improved or unchanged. Because the cases of telangiectasia seem to be of interest, two cases are described. 250 Neurol Med Chir Suppl (Tokyo) 38, 250 `254, 1998

Surgery of Angiomas in the Brainstem 251 Table 1 Surgical cases of angioma other than arteriovenous malformation in the brainstem (Kyushu University Hospital and affiliate hospitals 1987-1996) MVM: medullary venous malfomation. Case Presentation Case 4: A 17-year-old girl noticed mild weakness of her right hand fingers followed by double vision in several days. The motor weakness of the right hand progressed to right hemiparesis in a month. She was seen at department of neurology of our hospital. Positive neurological signs were bilateral abducens nerve palsy with medial rotation of the right eye, right spastic hemiparesis with pathological reflexes. MR imaging demonstrated a hematoma in the lower pons (Fig. 1), but no definite vascular abnormalities were demonstrated by MR imaging and cerebral angiography. She had been placed under observation. Nine months after the onset she developed rebleeding in the hematoma cavity, which caused nausea, vomiting, and swallowing difficulty. She was admitted to us and surgery was performed by the midline suboccipital approach. A bluish bulging of the fourth ventricle floor was incised in the midline and a dark bloody fluid escaped with increased pressure. Hematoma in the pons was evacuated and some thin-walled vessels on the cavity wall were left be- Fig. 2 Histological section of the removed hematoma wall in Case 4 showing thin-walled vascular spaces of various sizes intervened by the neural tissue with blood pigments and infiltrated leukocytes. The diagnosis is telangiectasia. HE stain, ~50. Fig. 1 T1- and T2-weighted magnetic resonance images of Case 4 9 months before admission. A hematoma with a niveau in the cavity is seen in the lower pons. Fig. 3 T1-weighted magnetic resonance images with contrast enhancement of Case 4 6 months after surgery. Rebleeding in the hematoma cavity continued. A thread-like contrast-enhancement suggesting the persisting abnormal vessels in the pons is seen.

252 M. Fukui et al. hind. Histological examination of the hematoma wall showed telangiectasia with blood pigments (Fig. 2). After surgery she showed improvement of the neurological signs. However, she continued to have insidious rebleeding in the hematoma cavity (Fig. 3). In the enhanced MR images a fine threadlike enhancement, which was considered the abnormal vessels in the pons, was seen (Fig. 3 right). She did not have abnormalities in the laboratory data on platelet aggregation, plasma fibrinolysis, and antibody of autoimmune diseases. She could go to school with mild trunkal ataxia and double vision. Around 1.5 years after surgery the insidious hemorrhage in the pons began to subside. Case 5: A 61-year-old male noticed abnormal taste and mild gait disturbance 9 months before admission to us. One month before admission he noticed loss of thermal sensation in the right half of the body. He was seen at a local hospital and was found to have a hematoma in the midbrain by computed tomography and MR imaging. He was still able to walk without assistance. However, dysarthria, double vision, unsteady gait, and sensory disturbance of the right extremities occurred and MR imaging demonstrated an increase of the hematoma. He was admitted to us to undergo evacuation of the hematoma. Positive neurological signs were horizontal nystagmus on the left lateral gaze, dysarthria, dyscoordination more on the left, marked trunkal ataxia, and right hemihypesthesia including the face. The hematoma was situated on the dorsal side of the midbrain on the left (Fig. 4). MR imaging and MR angiography did not demonstrate abnormal vessels around the hematoma. Surgery was performed by the left occipital transtentorial approach. The dorsal midbrain was exposed and a bluish bulging of the midbrain on Fig. 5 upper: Histological section of Case 5 showing numerous vascular cavities of varying sizes within a well-demarcated hematoma wall. HE stain, ~25. lower: In higher magnification, the thin-walled vascular cavities are intervened by the neural tissue. HE stain, ~160. Fig. 4 T1-andT2-weighted magnetic resonance images of Case 5 before surgery (9 months after the onset). Fig. 6 Enhanced magnetic resonance images of Case 5 6 months after surgery. No hematoma is seen but a thread-like intraparenchymal enhancement suggesting the abnormal vessels around the previous hematoma cavity is seen.

Surgery of Angiomas in the Brainstern 253 the left was incised sagittally. Darkish fluid and old clot were evacuated. Fine vessels were traversing the hematoma. Intraoperative impression was a ruptured cavernoma and the hematoma wall was removed. The opening of the midbrain was measured to be 5 mm after hematoma removal. Histological examination of the hematoma wall demonstrated telangiectasia (Fig. 5). MR images taken 6 months after surgery did not demonstrate hemorrhage but a tortuous thread-like enhancement around the previous hematoma cavity, which were considered the persisting abnormal blood vessels (Fig. 6). He was seen 1.5 years after surgery and did not show rebleeding in the hematoma cavity. He could walk with moderate trunkal ataxia. Discussion Though telangiectasias are known to be the most frequent angiomas in the brainstem, they are usually small and asymptomatic.8,12) However, symptomatic cases of large sizes4,5,14) and symptomatic cases due to massive hemorrhage2,13) were also reported. Loboto et al.7) collected 241 reported cases of angiographically occult intracranial vascular malformations including their own and found telangiectasia in 3.8% of the cases. Mixed cases of telangiectasia with cavernoma,1.5,9,10) AVM,3) and MVM11) were also reported and the names of "mixed vascular malformation"1,10) or "cerebral capillary malformation"9) are proposed. The radiological findings of telangiectasia after hemorrhage cannot be distinguished from those of cavernoma. Both angiomas do not show abnormal vessels on angiograms. It has been said as the characteristic of cavernoma that MR images show a reticulated core of mixed intensities surrounded by a low intensity rim on T2-weighted images. The MR images of telangiectasia in our cases, however, showed the same findings. The differential diagnosis between both angiomas before surgery is, thus, not possible. At surgery the diagnosis of telangiectasia could be obtained in our former case, because abnormal vessels were observed in the neural parenchyma outside of hematoma. In our latter case, however, the surgeon could not differentiate it from a cavernoma during surgery. The organized hematoma wall around a long-standing hematoma caused the macroscopical findings to resemble a cavernoma. Postoperatively MR imaging demonstrated a thread-like enhancement around the evacuated hematoma cavity, which was considered the persisting abnormal vessels around the hematoma cavity. Postoperative visualization of the abnormal vessels in the telangiectasia was probably due to some change of the blood vessels after surgery. Though cavernomas and telangiectasias belong to a single spectrum of disease, the treatments for both angiomas are different. Cavernoma can be totally removed without serious neurological deficits, but telangiectasia cannot be totally removed. Aggressive removal of the abnormal vessels in telangiectasia may cause serious neurological deficits. Gamma knife may be the treatment of choice for a surgically inaccessible cavernoma though much higher complications than for AVM have been reported,6) but it may not an indication for telangiectasia in the brainstem. Because preoperative differentiation of both entities is difficult, intraoperative careful observation is important. We should keep in mind that the radiological examinations cannot differentiate telangiectasia from cavernoma. Acknowledgments This work was partly supported by the scientific grant of the Ministry of Education, Science, Sports, and Culture, Japan to M. F. and T. I. References 1) Awad IA, Robinson JR Jr, Mohanty S, Este ML: Mixed vascular malformations of the brain: clinical and pathogenic considerations. Neurosurgery 33: 179-188, 1993 2) Bland LI, Lapham LW, Ketonen L, Okawara S-H: Acute cerebellar hemorrhage secondary to capillary telangiectasia in an infant. A case report. Arch Neurol 51: 1151-1154, 1994 3) Chang SD, Steinberg GK, Rosario M, Crowley RS, Hevner RF: Mixed arteriovenous malformation and capillary telangiectasia. A rare subset of mixed vascular malformations. Case report. J Neurosurg 86: 699-703, 1997 4) Farrell DF, Forno LS: Symptomatic capillary telangiectasis of the brainstem without hemorrhage. Report of an unusual case. Neurology 20: 341-346, 1970 5) Hayashi T, Fukui M, Shojima K, Utsunomiya H, Kawasaki K: Giant cerebellar hemangioma in an infant. Childs Nerv Syst 1: 230-233, 1985 6) Karlsson B, Kihistrom L, Lindquist C, Erricson K, Steiner L: Radiosurgery for cavernous malformation. J Neurosurg 88: 293-297, 1998 7) Loboto RD, Perez C, Rivas JJ, Cordobes F: Clinical, radiological, and pathological spectrum of angiographically occult intracranial vascular malformations. Analysis of 21 cases and review of the literature. J Neurosurg 68: 518-531, 1988 8) McCormick WF, Hardman JM, Boulter TR: Vascular malformations (angiomas) of the brain with special

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