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Angiographically occult arteriovenous malformations of the brainstem
Surg Neurol 1987;28:221-4
221
Angiographically Occult Arteriovenous Malformations of the Brainstem D. J. McFerran, M.A., M.B., B.Chir., P. V. Marks, F.R.C.S., and N. J. Garvan, F.R.C.S.I. Department of Neurosurgery, Oldchurch Hospital, Romford, Essex, England
McFerran DJ, Marks PV, Garvan NJ. Angiographically occult arteriovenous malformations of the brainstem. Surg Neurol 1987;28:221-4.
Two cases of infratentorial arteriovenous malformations that were occult to angiography but detected by computed tomography are discussed. In both cases a preoperative diagnosis of low-grade glioma was considered. Attention is drawn to the relative paucity of such lesions below the tentorium. KEY WORDS: Occult arteriovenous malformation; Computed tomography; Cerebral angiography; Posterior cranial fossa
Angiography has long been regarded as the definitive mode o f investigation for diagnosing cerebral arteriovenous malformations. Indeed, in 1948, Olivecrona and Riives [19] stated that "Arteriograms, of course, always disclose the presence o f an arteriovenous aneurysm." However, it was not long before this view was challenged by Crawford and Russell in 1956 [4], and since then, numerous authors have reported angiographically occult vascular malformations [ 1-3,6-8,10-18,20,22,23 ]. Almost all of these lesions were located in the supratentorial region. We report on two cases o f brainstem arteriovenous malformations that were angiographically occult and were considered to be neoplasms preoperatively. Case Reports Case 1 A 35-year-old right-handed woman presented to a neighboring hospital in 1981 with sudden onset of vertigo, vomiting, left facial weakness, and blurring of vision in her left eye. After investigation she was treated with steroid injections and made a good recovery. In 1982 and 1983 she suffered episodes of diplopia, which again responded to steroid treatment and at this time, Address reprint requests to: P. Marks, Addenbrookes Hospital, Hills Road, Cambridge, England.
© 1987 by Elsevier Science Publishing Co., Inc.
a diagnosis of disseminated sclerosis was made. In October 1984 she presented to our unit with ataxia, weakness and clumsiness of the right arm and both legs. She was dysarthric, had a left lateral rectus palsy, left lower motor neuron facial nerve palsy, and left sensorineural deafness. A computed tomography (CT) scan was performed (Figure 1) and demonstrated a large dense mass in the posterior cranial fossa. It was predominantly on the left and was displacing but not obstructing the fourth ventricle. T h e r e were irregular areas of calcification within the lesion and it showed slight enhancement after intravenous injection of contrast medium. Four vessel angiography (Figure 2) showed forward displacement of the anterior inferior cerebellar artery but no pathological vessels or other abnormality. Other investigations, including electroencephalogram, were within normal limits. Taking all these factors into consideration, a preoperative diagnosis of low-grade glioma was suggested. Surgical exploration revealed some discoloration of the pons, medial to the seventh and eighth nerve complex, but no obvious mass in the cerebellopontine angle. After retracting the cerebellar tonsils a yellow bulging mass was discovered in the fourth ventricle. The lesion was seen to involve the left half of the floor, extending to the left lateral margin o f the ventricle. Intraoperative frozen sections revealed that the mass was composed of arteries and veins. Because of the location of the lesion, only a partial resection was possible. Postoperatively, she made an unremarkable recovery, but due to her left-sided facial palsy, a lateral tarsorrhaphy was performed to forestall corneal damage. A formal histological examination confirmed that the mass was composed o f a tangle of arteries and veins with interspersed glia, consistent with an arteriovenous malformation.
Case 2 A 16-year-old right-handed girl developed a rapid onset, generalized headache in January 1985. She vomited, 0090-3019/87/$3.50
222
Surg Neurol 1987;28:221-4
Figure 1. Computed tomography scan of patient 1 showing enhancing mass displacing the fourth ventricle.
Figure 2. Subtracted vertebral angiogram of patient ! showing displacement of the anterior inferior cerebellar artery.
McFerran et al
Figure 3. Computed tomography scan of patient 2 showing an ill defined, slightly enhancing mass causing displacement of the fourth ventricle to the right.
complained of weakness in her legs, and, after 48 hours developed diplopia and weakness of the left arm. As there was some suspicion that this had been a subarachnoid hemorrhage, a lumbar puncture was performed at the referring hospital, 60 hours after the onset of symptoms. This was a difficult procedure and produced blood stained cerebrospinal fluid without a xanthochromic supernatant. It was therefore presumed to be a traumatic tap. She was transferred to our unit where she was noted to have nystagmus on left lateral gaze and a marked intention t r e m o r of the left arm. A C T scan (Figure 3) showed an abnormal low-density area near the superior vermis and in the region of the corpora quadrigemina. T h e fourth ventricle was displaced anteriorly and slightly to the right and was compressed, causing hydrocephalus. The lesion showed patchy enhancement after intravenous injection of contrast medium. An angiography was p e r f o r m e d and showed an arterial phase blush without any evidence of arteriovenous shunting. T h e preoperative diagnosis was a glioma. At surgery, the superior surface of the cerebellum was discolored and there was increased vascularity in the region of the vermis and around the tentorial hiatus. Biopsy specimens were taken from these areas, but were reported as normal. As no histological abnormality could be found, it was thought best to abandon the procedure.
Angiographically Occult Brainstem AVMs
H e r immediate postoperative recovery was rather slow but after 3 hours she started speaking and obeying commands. However, 5 hours later her consciousness level deteriorated abruptly and her blood pressure rose dramatically. A CT scan confirmed the clinical diagnosis of posterior fossa hematoma, which was subsequently evacuated. Postoperatively, she was maintained on a ventilator but despite all possible measures her condition continued to deteriorate and she died 6 days later. An autopsy was performed and revealed an arteriovenous malformation in the superior part of the cerebellum, extending into the midbrain (Figure 4). Discussion Arteriovenous malformations which are not demonstrated by angiography are well recognized but comparatively rare entities. They may present either as cases of spontaneous intracerebral hemorrhage, or rarely, by causing various neurological deficits. With this latter mode of presentation, seizures, motor deficits, or headaches appear to be the most common symptoms and in all the
Surg Neurol 1987;28:221-4
223
Figure 4. Photomicrograph of case 2 shou'ing many abnormal blood vessels dispersed throughout gliotic areas of brain. Some of the vessels are patent while others are hyalinized (H & E, × 60).
reported cases [ 1 - 3 , 6 - 8 , 1 0 - 1 7 , 2 0 , 2 3 ] the preoperative diagnosis was uncertain or misleading. Previous studies [5,9] have shown posterior fossa arteriovenous malformations to be much rarer than those located above the tentorium, representing only 7 % - 8 % of the total intracranial vascular malformations. Among angiographically occult arteriovenous malformations, presenting without evidence of subarachnoid hemorrhage, only one case has been reported in the posterior fossa [ 15]. The reason for the disparity in topographical location is uncertain. Many factors can result in the nonopacification of an arteriovenous malformation on angiography. First, the blood flow through the lesion may be so rapid or so slow that the opacification is missed by the serial films. Second, the characteristics of the arteriovenous malformation may preclude satisfactory visualization: if there
224
Surg Neurol 1987;28:221-4
has been a recent hemorrhage, the resulting hematoma may compress the feeding vessels, preventing adequate amounts of contrast medium to reach the lesion. Spontaneous thrombosis may occur and, indeed, it has been suggested that the vessels comprising an arteriovenous malformation may have a greater proclivity to become thrombotic than normal vessels [21]. Some lesions, such as cavernous angiomas, may have blood supplies that are anatomically separate from the cerebral circulation and hence are not seen on standard cerebral angiography. Patients with posterior fossa masses revealed by CT scans may have arteriovenous malformations, even in the presence of an angiogram which suggests a different diagnosis. Therefore, we feel it is important for the surgeon to be aware of the possibility that an ill defined or indefinite lesion beneath the tentorium may be a vascular malformation that may not have filled on angiography. References 1. Becker DH, Townsend JJ, Kramer RA, Newton TH. Occult cerebrovascular malformations. A series of 18 histologically verified cases with negative angiography. Brain 1979;102:249-87. 2. Bell BA, Kendall BE, Symon L. Angiographically occult arteriovenous malformations of the brain. J Neurol Neurosurg Psychiatry 1978;41:1057-64. 3. Chin D, Harper C. Angiographically occult cerebral vascular malformations with abnormal computed tomography. Surg Neurol 1983;20:138-42. 4. Crawford JV, Russell DS. Cryptic arteriovenous and venous hamartomas of the brain. J Neurol Neurosurg Psychiatry 1956;19: 1-11. 5. Drake CG, Friedman AH, Peerless SJ. Posterior fossa arteriovenous malformations. J Neurosurg 1986;64:1-10. 6. Dyck P. Spontaneous thrombosis of an arteriovenous malformation. Neurosurgery 1977;1:287-90. 7. Edgar R, Baldwin M. Vascular malformations associated with temporal lobe epilepsy. J Neurosurg 1960;17:638-56. 8. Golden JB, Kramer RA. The angiographically occult cerebro-
McFerran et al
vascular malformation. Report of three cases.J Neurosurg 1978;48: 292-6. 9. Graf CJ, Perret GE, Torner JC. Bleeding from cerebral arteriovenous malformations as part of their natural history. J Neurosurg 1983;58:331-7. 10. Hashim ASM, Asakura T, Koichi U, Kadota K, Awa H, Kusumoto K, Yamashita K. Angiographically occult arteriovenous malformations. Surg Neurol 1985;23:431-9. 11. Jabbari B, Huott H, Di Chiro G, Martins AN, Youngblood LA, Harper MG. Surgically correctable lesions solely detected by CT scan in adult-onset chronic epilepsy. Ann Neurol 1980;7:344-7. 12. Kamrin RB, Buchsbaum HW. Large vascular malformations of the brain not visualized by serial angiography. Arch Neuro11965;13: 413-20. 13. Kendall BE, Claveria LE. The use of computed axial tomography (CAT) for the diagnosis and management of intracranial angiomas. Neuroradiology 1976;12:141-60. 14. Kramer RA, Wing SD. Computed tomography of angiographically occult vascular malformations. Radiology 1977; 123:649-52. 15. Leblanc R, Ethier R, Little JR. Computed tomography findings in arteriovenous malformations of the brain. J Neurosurg 1979;51: 765-72. 16. Lukin RR, Chambers AA, Tomsick TA. Cerebral vascular lesions: infarction, haemorrhage, aneurysm and arteriovenous malformation. Semin Roentgenol 1977;12:77-89. 17. Maehara T, Tasaka A. Rare vascular malformations of the brain. Computed tomography and angiographic diagnosis. No Shinkei Geka 1981;33.11:1147-55. 18. McCormick WF, NofzingerJD. "Cryptic" vascular malformations of the central nervous system. J Neurosurg 1966;24:865-75. 19. Olivecrona H, Riives J. Arteriovenous aneurysms of the brain. Their diagnosis and treatment. Arch Neurol Psychiatry 1948;59: 567-602. 20. Paterson JH, McKissock W. A clinical survey of intracranial angiomas with special reference to their mode of progression and surgical treatment: a report of 110 cases. Brain 1956;79:233-66. 21. Sukoff MH, Barth B, Moran T. Spontaneous occlusion of a massive arteriovenous malformation. A case report. Neuroradiology 1972;4:121-3. 22. Terao H, Hori T, Matsutani M, Okeda R. Detection of cryptic vascular malformations by computerized tomography. J Neurosurg 1979;51:546-51. 23. Wharren RE, Scheithauer BW, Laws ERJr. Thrombosed arteriovenous malformations of the brain. J Neurosurg 1982;57: 520-6.
221
Angiographically Occult Arteriovenous Malformations of the Brainstem D. J. McFerran, M.A., M.B., B.Chir., P. V. Marks, F.R.C.S., and N. J. Garvan, F.R.C.S.I. Department of Neurosurgery, Oldchurch Hospital, Romford, Essex, England
McFerran DJ, Marks PV, Garvan NJ. Angiographically occult arteriovenous malformations of the brainstem. Surg Neurol 1987;28:221-4.
Two cases of infratentorial arteriovenous malformations that were occult to angiography but detected by computed tomography are discussed. In both cases a preoperative diagnosis of low-grade glioma was considered. Attention is drawn to the relative paucity of such lesions below the tentorium. KEY WORDS: Occult arteriovenous malformation; Computed tomography; Cerebral angiography; Posterior cranial fossa
Angiography has long been regarded as the definitive mode o f investigation for diagnosing cerebral arteriovenous malformations. Indeed, in 1948, Olivecrona and Riives [19] stated that "Arteriograms, of course, always disclose the presence o f an arteriovenous aneurysm." However, it was not long before this view was challenged by Crawford and Russell in 1956 [4], and since then, numerous authors have reported angiographically occult vascular malformations [ 1-3,6-8,10-18,20,22,23 ]. Almost all of these lesions were located in the supratentorial region. We report on two cases o f brainstem arteriovenous malformations that were angiographically occult and were considered to be neoplasms preoperatively. Case Reports Case 1 A 35-year-old right-handed woman presented to a neighboring hospital in 1981 with sudden onset of vertigo, vomiting, left facial weakness, and blurring of vision in her left eye. After investigation she was treated with steroid injections and made a good recovery. In 1982 and 1983 she suffered episodes of diplopia, which again responded to steroid treatment and at this time, Address reprint requests to: P. Marks, Addenbrookes Hospital, Hills Road, Cambridge, England.
© 1987 by Elsevier Science Publishing Co., Inc.
a diagnosis of disseminated sclerosis was made. In October 1984 she presented to our unit with ataxia, weakness and clumsiness of the right arm and both legs. She was dysarthric, had a left lateral rectus palsy, left lower motor neuron facial nerve palsy, and left sensorineural deafness. A computed tomography (CT) scan was performed (Figure 1) and demonstrated a large dense mass in the posterior cranial fossa. It was predominantly on the left and was displacing but not obstructing the fourth ventricle. T h e r e were irregular areas of calcification within the lesion and it showed slight enhancement after intravenous injection of contrast medium. Four vessel angiography (Figure 2) showed forward displacement of the anterior inferior cerebellar artery but no pathological vessels or other abnormality. Other investigations, including electroencephalogram, were within normal limits. Taking all these factors into consideration, a preoperative diagnosis of low-grade glioma was suggested. Surgical exploration revealed some discoloration of the pons, medial to the seventh and eighth nerve complex, but no obvious mass in the cerebellopontine angle. After retracting the cerebellar tonsils a yellow bulging mass was discovered in the fourth ventricle. The lesion was seen to involve the left half of the floor, extending to the left lateral margin o f the ventricle. Intraoperative frozen sections revealed that the mass was composed of arteries and veins. Because of the location of the lesion, only a partial resection was possible. Postoperatively, she made an unremarkable recovery, but due to her left-sided facial palsy, a lateral tarsorrhaphy was performed to forestall corneal damage. A formal histological examination confirmed that the mass was composed o f a tangle of arteries and veins with interspersed glia, consistent with an arteriovenous malformation.
Case 2 A 16-year-old right-handed girl developed a rapid onset, generalized headache in January 1985. She vomited, 0090-3019/87/$3.50
222
Surg Neurol 1987;28:221-4
Figure 1. Computed tomography scan of patient 1 showing enhancing mass displacing the fourth ventricle.
Figure 2. Subtracted vertebral angiogram of patient ! showing displacement of the anterior inferior cerebellar artery.
McFerran et al
Figure 3. Computed tomography scan of patient 2 showing an ill defined, slightly enhancing mass causing displacement of the fourth ventricle to the right.
complained of weakness in her legs, and, after 48 hours developed diplopia and weakness of the left arm. As there was some suspicion that this had been a subarachnoid hemorrhage, a lumbar puncture was performed at the referring hospital, 60 hours after the onset of symptoms. This was a difficult procedure and produced blood stained cerebrospinal fluid without a xanthochromic supernatant. It was therefore presumed to be a traumatic tap. She was transferred to our unit where she was noted to have nystagmus on left lateral gaze and a marked intention t r e m o r of the left arm. A C T scan (Figure 3) showed an abnormal low-density area near the superior vermis and in the region of the corpora quadrigemina. T h e fourth ventricle was displaced anteriorly and slightly to the right and was compressed, causing hydrocephalus. The lesion showed patchy enhancement after intravenous injection of contrast medium. An angiography was p e r f o r m e d and showed an arterial phase blush without any evidence of arteriovenous shunting. T h e preoperative diagnosis was a glioma. At surgery, the superior surface of the cerebellum was discolored and there was increased vascularity in the region of the vermis and around the tentorial hiatus. Biopsy specimens were taken from these areas, but were reported as normal. As no histological abnormality could be found, it was thought best to abandon the procedure.
Angiographically Occult Brainstem AVMs
H e r immediate postoperative recovery was rather slow but after 3 hours she started speaking and obeying commands. However, 5 hours later her consciousness level deteriorated abruptly and her blood pressure rose dramatically. A CT scan confirmed the clinical diagnosis of posterior fossa hematoma, which was subsequently evacuated. Postoperatively, she was maintained on a ventilator but despite all possible measures her condition continued to deteriorate and she died 6 days later. An autopsy was performed and revealed an arteriovenous malformation in the superior part of the cerebellum, extending into the midbrain (Figure 4). Discussion Arteriovenous malformations which are not demonstrated by angiography are well recognized but comparatively rare entities. They may present either as cases of spontaneous intracerebral hemorrhage, or rarely, by causing various neurological deficits. With this latter mode of presentation, seizures, motor deficits, or headaches appear to be the most common symptoms and in all the
Surg Neurol 1987;28:221-4
223
Figure 4. Photomicrograph of case 2 shou'ing many abnormal blood vessels dispersed throughout gliotic areas of brain. Some of the vessels are patent while others are hyalinized (H & E, × 60).
reported cases [ 1 - 3 , 6 - 8 , 1 0 - 1 7 , 2 0 , 2 3 ] the preoperative diagnosis was uncertain or misleading. Previous studies [5,9] have shown posterior fossa arteriovenous malformations to be much rarer than those located above the tentorium, representing only 7 % - 8 % of the total intracranial vascular malformations. Among angiographically occult arteriovenous malformations, presenting without evidence of subarachnoid hemorrhage, only one case has been reported in the posterior fossa [ 15]. The reason for the disparity in topographical location is uncertain. Many factors can result in the nonopacification of an arteriovenous malformation on angiography. First, the blood flow through the lesion may be so rapid or so slow that the opacification is missed by the serial films. Second, the characteristics of the arteriovenous malformation may preclude satisfactory visualization: if there
224
Surg Neurol 1987;28:221-4
has been a recent hemorrhage, the resulting hematoma may compress the feeding vessels, preventing adequate amounts of contrast medium to reach the lesion. Spontaneous thrombosis may occur and, indeed, it has been suggested that the vessels comprising an arteriovenous malformation may have a greater proclivity to become thrombotic than normal vessels [21]. Some lesions, such as cavernous angiomas, may have blood supplies that are anatomically separate from the cerebral circulation and hence are not seen on standard cerebral angiography. Patients with posterior fossa masses revealed by CT scans may have arteriovenous malformations, even in the presence of an angiogram which suggests a different diagnosis. Therefore, we feel it is important for the surgeon to be aware of the possibility that an ill defined or indefinite lesion beneath the tentorium may be a vascular malformation that may not have filled on angiography. References 1. Becker DH, Townsend JJ, Kramer RA, Newton TH. Occult cerebrovascular malformations. A series of 18 histologically verified cases with negative angiography. Brain 1979;102:249-87. 2. Bell BA, Kendall BE, Symon L. Angiographically occult arteriovenous malformations of the brain. J Neurol Neurosurg Psychiatry 1978;41:1057-64. 3. Chin D, Harper C. Angiographically occult cerebral vascular malformations with abnormal computed tomography. Surg Neurol 1983;20:138-42. 4. Crawford JV, Russell DS. Cryptic arteriovenous and venous hamartomas of the brain. J Neurol Neurosurg Psychiatry 1956;19: 1-11. 5. Drake CG, Friedman AH, Peerless SJ. Posterior fossa arteriovenous malformations. J Neurosurg 1986;64:1-10. 6. Dyck P. Spontaneous thrombosis of an arteriovenous malformation. Neurosurgery 1977;1:287-90. 7. Edgar R, Baldwin M. Vascular malformations associated with temporal lobe epilepsy. J Neurosurg 1960;17:638-56. 8. Golden JB, Kramer RA. The angiographically occult cerebro-
McFerran et al
vascular malformation. Report of three cases.J Neurosurg 1978;48: 292-6. 9. Graf CJ, Perret GE, Torner JC. Bleeding from cerebral arteriovenous malformations as part of their natural history. J Neurosurg 1983;58:331-7. 10. Hashim ASM, Asakura T, Koichi U, Kadota K, Awa H, Kusumoto K, Yamashita K. Angiographically occult arteriovenous malformations. Surg Neurol 1985;23:431-9. 11. Jabbari B, Huott H, Di Chiro G, Martins AN, Youngblood LA, Harper MG. Surgically correctable lesions solely detected by CT scan in adult-onset chronic epilepsy. Ann Neurol 1980;7:344-7. 12. Kamrin RB, Buchsbaum HW. Large vascular malformations of the brain not visualized by serial angiography. Arch Neuro11965;13: 413-20. 13. Kendall BE, Claveria LE. The use of computed axial tomography (CAT) for the diagnosis and management of intracranial angiomas. Neuroradiology 1976;12:141-60. 14. Kramer RA, Wing SD. Computed tomography of angiographically occult vascular malformations. Radiology 1977; 123:649-52. 15. Leblanc R, Ethier R, Little JR. Computed tomography findings in arteriovenous malformations of the brain. J Neurosurg 1979;51: 765-72. 16. Lukin RR, Chambers AA, Tomsick TA. Cerebral vascular lesions: infarction, haemorrhage, aneurysm and arteriovenous malformation. Semin Roentgenol 1977;12:77-89. 17. Maehara T, Tasaka A. Rare vascular malformations of the brain. Computed tomography and angiographic diagnosis. No Shinkei Geka 1981;33.11:1147-55. 18. McCormick WF, NofzingerJD. "Cryptic" vascular malformations of the central nervous system. J Neurosurg 1966;24:865-75. 19. Olivecrona H, Riives J. Arteriovenous aneurysms of the brain. Their diagnosis and treatment. Arch Neurol Psychiatry 1948;59: 567-602. 20. Paterson JH, McKissock W. A clinical survey of intracranial angiomas with special reference to their mode of progression and surgical treatment: a report of 110 cases. Brain 1956;79:233-66. 21. Sukoff MH, Barth B, Moran T. Spontaneous occlusion of a massive arteriovenous malformation. A case report. Neuroradiology 1972;4:121-3. 22. Terao H, Hori T, Matsutani M, Okeda R. Detection of cryptic vascular malformations by computerized tomography. J Neurosurg 1979;51:546-51. 23. Wharren RE, Scheithauer BW, Laws ERJr. Thrombosed arteriovenous malformations of the brain. J Neurosurg 1982;57: 520-6.