|Year : 2018 | Volume
| Issue : 2 | Page : 108-110
Brain stem arteriovenous malformations: Was preoperative diagnosis possible in this case?
Department of Neurosurgery, Narayana Medical College Hospital, Nellore, Andhra Pradesh, India
|Date of Web Publication||23-Nov-2018|
Dr. Amit Agrawal
Department of Neurosurgery, Narayana Medical College Hospital, Chinthareddypalem, Nellore - 524 003, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Arteriovenous malformations (AVMs) involving brain stem in children are uncommon. These lesions usually present as hemorrhage as the first manifestation. When these lesions present both clinically and radiologically as a mass lesion without hemorrhage, it is very difficult to make a preoperative diagnosis of AVM as in the present case. With sophisticated imaging modalities, it may be possible to suspect this diagnosis; however, with limited facilities still, it will be difficult to approach these lesions as in present case.
Keywords: Arteriovenous malformation, brain stem, vascular lesions
|How to cite this article:|
Agrawal A. Brain stem arteriovenous malformations: Was preoperative diagnosis possible in this case?. J Datta Meghe Inst Med Sci Univ 2018;13:108-10
| Introduction|| |
A brainstem arteriovenous malformation (AVM) as an AVM in which some part of the lesion is located within the brainstem. Brain stem AVMs represent only 2%–6% of all cerebral AVMs, however, they pose a great management challenge.,, These lesions are no longer cryptic. Prompt diagnosis and anatomic evaluation of patients with brainstem hemorrhages resulting from AVMs have been greatly facilitated by high-resolution computed tomography (CT) scanning and particularly magnetic resonance image (MRI) scanning., However, all these facilities may not be available at all centers particularly in developing countries and can pose a difficult challenges and limitations to the neurosurgeons in diagnosing and managing these patients as in the present case.
| Case Report|| |
This 12 years child presented with weakness of the left half of the body for the last 16 days, deviation of angle of mouth to right side with a history of difficulty in speaking and drooling of saliva. There was no history of a headache, fever, cough, or bowel/bladder disturbances. On examination, his higher mental functions were normal. He had pyramidal type of weakness in the left upper and lower limb. He had left upper motor neuron facial nerve palsy. Extraocular movements were full. He had bilateral nystagmus. He was not able to walk without support. He also had right cerebellar signs. With all these findings, possibility of the brain stem mass lesion was considered. His CT scan plain and contrast showed isodense lesion involving midbrain and extending into the, right superior cerebellar peduncle and right cerebellar hemisphere and enhancing well with contrast. There was associated perilesional edema but no hydrocephalus [Figure 1], [Figure 2], [Figure 3]. A possibility of glioma versus tuberculoma was considered. At our center, we do not have facility of MRI or angiogram. In addition, the patient could not be referred to another center because of financial constraints. To confirm the diagnosis, he underwent right retromastoid suboccipital craniectomy and microscopic decompression of the lesion. The lesion was moderately vascular, grayish with ill-defined plane of cleavage. After partial decompression, it was felt that it is not safe to decompression the lesion which was extending into the midbrain. Postoperatively, the child recovered well without any new deficits. To our surprise, histopathology of the specimen showed AVM with normal brain parenchyma [Figure 4] and [Figure 5].
|Figure 1: Computed tomography scan plain (left) and contrast (right) showing isodense lesion involving upper brain stem on right side and extending into the right cerebellar hemisphere with enhancement with contrast. There is mild distortion of 4th ventricle|
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|Figure 3: Postcontrast coronal reconstruction showing well-defined enhancing lesion involving brain stem|
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|Figure 4: Histopathology suggestive of arteriovenous malformation with normal brain parenchyma|
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|Figure 5: There was presence of dilated vascular channels and hyalinized vessel, features suggestive of arteriovenous malformation|
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| Discussion|| |
Clinically manifest AVMs in children are rare, and few pediatric series have been reported., In children, the most common initial symptom of AVM is hemorrhagic stroke with high mortality and morbidity rates., Infratentorial AVM location is independently associated with higher frequencies of AVM rupture and hemorrhagic AVM presentation. About 80%–90% of patients initially presented with an intracranial hemorrhage,, and the risk of hemorrhage in untreated patients is estimated to be 60% in 10 years. Like any mass lesion, the most frequent symptoms of brain stem AVMs are eye movement disturbances, followed by cerebellar, and pyramidal signs. At the time of presentation, most patients of these patients are ambulatory with good Karnofsky Performance Status and cannot be differentiated clinical with any other brain stem lesion as in the present case. MR angiography is a new noninvasive angiographic technique which is very useful for screening and follow-up of AVM in the brain. Axial MR angiography can also distinguish perforating arteries from the main trunk or nidus which may overlap on conventional angiography.,, MRI has renewed interest in the treatment of this disorder because of the precise accuracy in diagnosis and localization of these lesions that it affords. The MR image demonstrates the characteristic findings of multiple hemorrhages of varying ages surrounded by a hypointense peripheral zone of hemosiderin. The vascular malformations could be demonstrated as “flow void” areas. At our center, all these facilities are not available, and for the patient, finances were the major limitations. In the present case based on CT scan findings, we did not consider the possibility of brain stem AVM and after histopathology only the diagnosis of brain stem AVM could be made. From the management point of view, there is no solid consensus on the optimal treatment protocols for these lesions at present. The goal of any treatment is complete occlusion of the malformation with minimal risk to the patient, primarily to prevent rebleeding and further neurologic injury from the AVM. Utilizing modern microsurgical techniques, surgical resection can be applied with considerable, but acceptable, morbidity and mortality in some groups of the brainstem, AVMs with hemorrhagic presentation, particularly dorsal midbrain and cerebellopontine angle types, in which most parts of the nidus located sub- or extrapially. Endovascular management of a brain-stem AVM may be an alternative to treatment such as radiosurgery and microsurgery in selected cases. It may be not as risky as previously thought. Embolization can reduce the size of the AVM and possibly make it more treatable by radiosurgery and decrease the possibility of radiation injury., This case illustrates in the absence of bleed it is difficult to make a pre-operative diagnosis of arteriovenous particularly when lesion looks like a solid tumor on the CT scan, and there are limited facility to investigate the patient.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]