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|Year : 2020 | Volume
| Issue : 5 | Page : 1203-1206
Cavernous Hemangioma of the Trochlear Nerve in Asian Population: Case Report and Review of the Literature
Peng Wang1, Weihai Ning2, Yanming Qu2, Hongwei Zhang2
1 Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing; Department of Neurosurgery, Chengdu Fifth People's Hospital, Chengdu, China
2 Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
|Date of Web Publication||27-Oct-2020|
Dr. Hongwei Zhang
Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, No. 50 Yikesong Road, Xiangshan Ave, Beijing 100093
Source of Support: None, Conflict of Interest: None
Trochlear nerve cavernous hemangioma (CH) is a rare disease. There have been only five such cases reported in the world literature till date. The authors report a case of trochlear nerve CH in the Asian population and review the relevant literature. A 49-year-old Asian woman presented with gradually worsening double vision for 6 years. Physical examination identified a complete paralysis of left trochlear nerve. In imaging, a circular lesion measuring about 1 cm in diameter was found in the left ambient cistern. The lesion was completely excised through the left-side subtemporal approach, with a diagnosis of trochlear nerve CH confirmed by pathological examination. Further nerve anastomosis was not adopted, and the patient remained clinically stable in a two years' follow-up. This report provides more information about the history characteristics, imaging features, and surgical treatment strategies for trochlear nerve CH.
Keywords: Cavernous hemangioma, cranial nerve neoplasms, trochlear nerve
Key Message: Trochlear nerve cavernous hemangioma is a very rare intracranial vascular lesion. This report shows a case of trochlear nerve CH in the Asian population.
|How to cite this article:|
Wang P, Ning W, Qu Y, Zhang H. Cavernous Hemangioma of the Trochlear Nerve in Asian Population: Case Report and Review of the Literature. Neurol India 2020;68:1203-6
Author 1 and 2 contributed equally
Cavernous hemangiomas (CHs), characterized by abnormal blood vessels with different stages of thrombosis, are low-flow and angiographically occult vascular lesions. They are the second most intracranial vascular malformations, which are usually located in the parenchyma. However, CHs involving the trochlear nerve are extremely rare. So far, only five cases have been recorded in the literature,,,,, and the patients were all from non-Asian areas. As a result, we report an exceptionally rare case of trochlear nerve CH in the Asian population and discuss the imaging, histopathological characteristics, and management strategy.
| » Case History|| |
A 49-year-old Asian woman was admitted to our department for gradually worsening double vision for six years. Neurological examination illustrated a complete paralysis of the left trochlear nerve. On computed tomography (CT) scan, a slightly high-density lesion measuring about 1 cm in diameter was found in the left ambient cistern [Figure 1]a, which was significantly enhanced after injection of contrast medium [Figure 1]b. Magnetic resonance (MR) imaging showed the lesion was hypointense in T1w images [Figure 1]c, mixed-signal intense in T2w images [Figure 1]d, and hyperintense in FLAIR [Figure 1]e, with heterogeneous enhancement on postgadolinium T1-weighted sequences [Figure 1]f, [Figure 1]g, [Figure 1]h. No vascular abnormality was found in CT angiography [Figure 1]i.
|Figure 1: Preoperative images of trochlear nerve CH. A moderate high-density circular lesion (a) with significant enhancement (b) was found in the left cistern of the brainstem on CT scan. In MR, the lesion showed hypointense in T1w axial image (c), mixed signal intense in T2w axial image (d) and hyperintense in FLAIR (e), with heterogeneous enhancement on postgadolinium T1-weighted sequences (f-h). No obvious cerebrovascular abnormality was found in CT angiography (i)|
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Surgery via the left-side subtemporal approach was adopted, and a mulberry-like lesion enclosed the trochlear nerve was identified in the left ambient cistern [Figure 2]a and [Figure 2]b. The operation only removed the lesion and affected nerve without further anastomosis, because nerve paralysis had been lasting for a long time [Figure 2]c. The diagnosis of CH was confirmed by histopathological examination found thrombosis in most lumen [Figure 3]a and [Figure 3]b. The elastic fibers were negative in the sinus wall [Figure 3]c, and CD34 was positive which highlights the endothelial cells [Figure 3]d. Postoperatively, complete resection was achieved by imaging evaluation, and no additional nerve damage was added in the patient [Figure 4]. The woman represented a persistent left fourth nerve palsy in a two years' follow-up, with no recurrence observed.
|Figure 2: Intraoperative photographs. A mulberry-like lesion was identified in the left cistern of the brainstem via a left-side subtemporal approach (a), with the trochlear nerve found to be partly enclosed (b). The neoplasm and affected part of the nerve were completely excised without further neurorrhaphy (c)|
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|Figure 3: Pathological pictures. Thrombosis was found in most of the lumen on HE staining (a), with scattered lymphocyte infiltration and hemosiderin deposition (b). Further immunohistochemical staining showed that the elastic fibers were negative in the sinus wall (c), and CD34 was positive which highlights endothelial cells (d)|
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|Figure 4: Postoperative images. A complete resection of the lesion was ascertained by postoperative T1-enhanced MR images in axial (a), sagittal (b) and coronal plane (c)|
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| » Literature Review of the Trochlear Nerve Chs|| |
As the existence of the first trochlear nerve CH was confirmed in 1992, only six cases were reported in the world, including the present one [Table 1]. The age ranged from 31 to 70 and the ratio of males to females was 4:2. Diplopia was the main symptom, accounting for two-thirds of patients, in which the durations varied in different cases. In four cases, the lesions located on the left, and in two cases on the right. Surgical resection and anastomosis preferred to be performed in the patients with incidental onset or short medical history, also pure operation removal tended to be the procedure for people with symptoms for months or years. Postoperative paralysis of the trochlear nerve was more likely to occur in patients who had long preoperative history and simple surgical excision.
|Table 1: Summary of cases reported on cavernous hemangiomas of the trochlear nerve|
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| » Discussion|| |
Although more than 40 cases have been reported,, cranial nerve CHs are still a very rare disease, especially those involving the trochlear nerve. According to the reported cases,,,,, trochlear nerve CHs were mostly located in the cistern of the brainstem and only occurred in adults.
Diplopia, which caused by a neurological disorder of the fourth cranial nerve, is the main symptom for the patients. In early reports,, this symptom was found to occur suddenly or persist for a short time. Kraschl et al. pointed out that the sudden trochlear nerve palsy was a significant difference between CH and schwannoma. However, the duration was much longer in later case and the present one, which makes the distinguishing point meaningless. This phenomenon may be due to the vulnerability of the trochlear nerve itself resulting in sudden onset of symptoms. On the contrary, the phenomenon may be related to the trochlear nerve which innervates the superior oblique muscle, only causing slight nerve paralysis to be ignored.
The imaging differential diagnoses mainly include schwannoma, neurofibroma, and hemangioma. Schwannoma was reported to involve the trochlear nerve in some cases. On CT, the lesion presented as round hypodensity with moderate enhancement. On MR imaging, the lesion showed low signal on T1w images and high signal on T2w images, and could be accompanied by cystic degeneration., Neurofibroma is another common trochlear nerve neoplasm, of which the CT and MR findings are as similar with the cases of Schwannoma. Nevertheless, neurofibroma is more prone to calcification, with lower incidence of cystic degeneration. The third differential diagnosis is hemangioma. According to this case, the imaging features of trochlear nerve CH can be summarized as a moderate high density on CT, mixed signal on MR T2w images, and uneven enhancement without cystic degeneration and calcification. These image findings may indicate the existence of trochlear never CHs, but can barely make a definite preoperative diagnosis because of the extremely rare incidence.
Although the reasonable treatments include observation, surgery, and stereotactic radiotherapy, all CHs involving trochlear nerve has been reported to be surgically excised for symptomatic relief and obtaining histological diagnoses.,,,, Unlike the intraparenchymal type, trochlear nerve CHs usually have no distinct boundary with affected tissue, so that it is difficult to preserve the target nerve while resection. Some scholars recommend a further nerve repair,,, but others believe that neurorrhaphy is not a treatment option for patients who had a long-term diplopia., In the present report, the lesion and affected nerve was cut off without further anastomosis, because separating the encapsulated trochlear nerve exists difficulties and nerve anastomosis may be hard to bring a significant neurological recovery in a condition of six-year nerve palsy.
| » Conclusion|| |
Trochlear nerve CH is a rare disease, which can occur in the Asian population. Diplopia is the usual complaint and some patients may present late. Possible imaging features include slightly high density on CT, mixed signal on MR T2WI images, and uneven enhancement without cystic degeneration and calcification. However, image-based diagnosis remains challenging preoperatively. Patients with a long history are suggested to undergo simple surgical excision without nerve anastomosis.
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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