Abstract BACKGROUND AND IMPORTANCE Cavernous malformations (CMs) are vascular abnormalities with a hemorrhage risk of 0.2% to 5% per year, according to their location. Brainstem CMs seem to have a greater hemorrhagic risk and represent a neurosurgical challenge. We report here the first transsylvian transuncal (TS-TU) approach for an anteromedial mesencephalic CM resection. CLINICAL PRESENTATION A 29-yr-old female suddenly presented a left hemiparesis and central facial paresis with a diplopia in the upward gaze. A cerebral imagery revealed an 18-mm right cerebral peduncle CM with signs of acute hemorrhage. Two months later, she rebleed while pregnant. The pregnancy was interrupted. Five months later, a 3.0 Tesla magnetic resonance imaging (MRI) with diffusion tensor imaging sequences was realized for preoperative planning followed by a gross total resection of the CM through a TS-TU approach to avoid the perforating arteries of the anterior perforated substance. The patient presented postoperatively again a left hemiparesis and central facial paresis with a right oculomotor nerve paresis. On the tenth postsurgical day, she developed a Holmes’ tremor of the left upper limb, for which a Levodopa treatment was initiated. Three months postoperative, MRI showed a gross total resection of the mesencephalic CM without complications. A complete clinical recovery was observed 1 yr later. CONCLUSION We describe here the first performance of a TS-TU approach for an anterior mesencephalic CM resection. This surgical approach allowed direct access to the CM, avoiding the vascularization of the anterior perforated substance. Anterior midbrain cavernous malformation, Mesencephalon, Brainstem cavernoma, Holme's tremor, Transsylvian transuncal approach, Case report ABBREVIATIONS ABBREVIATIONS APS anterior perforated su-bstance CMs cavernous malformations DTI diff-usion tensor imaging GTR gross total resection HT Holme's tremor MRI magnetic resonance imaging PT pyramidal tract TS-TU transsylvian transuncal Cavernous malformations (CM) are vascular hamartomas made up of a cluster of spindly dilated blood vessels. Brainstem CMs, which represent 9% to 35% of all intracranial CMs,1-7 have a bleeding risk of 2.7% to 5% per year,4,7,8 and a recurrent risk between 5% and 60% per year.2,3-5,8 The goal treatment for these deep-seated lesions is a hemorrhagic prophylaxis by performing a gross total resection (GTR). A resection is recommended for an accessible brainstem CM after 1 episode of bleeding in a symptomatic patient.5 We report the case of a young woman with a right cerebral peduncle CM. After meticulous preoperative planning, we performed a transsylvian transuncal (TS-TU) approach, which allowed us to avoid and preserve the anterior perforated substance (APS) vascularization. Patient Consent The patient consented to the submission of the case report and her image to the journal. FIGURE 1. View largeDownload slide Timeline. FIGURE 1. View largeDownload slide Timeline. CLINICAL PRESENTATION This case report concerns a 29-yr-old right-handed female without any past medical history. She suddenly experienced a left hemiparesis and central facial paresis with a vertical diplopia in the upward gaze (Figure 1). A magnetic resonance imaging (MRI) revealed a right 18-mm crus cerebri tegmental CM with signs of acute hemorrhage. A bleeding recurrence was observed 2 mo later after the first 5 wk of pregnancy with the same symptomatology. The patient underwent a medical abortion 2 mo before surgery. Clinical improvement was shown without any deficit in the preoperative testing. We performed a 3.0-Tesla cerebral MRI (Magnetom Verio, Siemens®, Malvern, Pennsylvania) with diffusion tensor imaging (DTI) sequences the day before surgery, disclosing a laterally displaced pyramidal tract (PT) (Figures 2 and 3). We used the iPlan software (BrainLab®, Feldkirchen, Germany) for surgical planification (Figures 4A-4D). The 2-point method introduced by Spetzler et al9 was used to preoperatively select the surgical route, which was a transsylvian approach. FIGURE 2. View largeDownload slide Preoperative axial T2-weighted brain MRI showing a right 18-mm crus cerebri tegmental CM abutting the pial surface with signs of hemorrhage. FIGURE 2. View largeDownload slide Preoperative axial T2-weighted brain MRI showing a right 18-mm crus cerebri tegmental CM abutting the pial surface with signs of hemorrhage. FIGURE 3. View largeDownload slide Preoperative sagittal T2-weighted brain MRI showing a right 18-mm crus cerebri tegmental cavernous malformation with signs of hemorrhage. FIGURE 3. View largeDownload slide Preoperative sagittal T2-weighted brain MRI showing a right 18-mm crus cerebri tegmental cavernous malformation with signs of hemorrhage. FIGURE 4. View largeDownload slide Preoperative planning using iPlan software (BrainLab®) with the right pyramidal tract (in red) laterally moved by the cavernous malformation (in green). In blue is the approach that was realized. A shows the 3D representation of the patient's head. The different plans are represented in B (axial), C (sagittal), and D (coronal). FIGURE 4. View largeDownload slide Preoperative planning using iPlan software (BrainLab®) with the right pyramidal tract (in red) laterally moved by the cavernous malformation (in green). In blue is the approach that was realized. A shows the 3D representation of the patient's head. The different plans are represented in B (axial), C (sagittal), and D (coronal). We began the procedure with a curvilinear skin incision from the right zygomatic arch to the midline behind the hairline. A pterional craniotomy was performed before a curvilinear dural incision. We widely opened the sylvan fissure and visualized the Sylvian bifurcation and multiple lateral lenticulostriate arteries arising from the M1 segment (Figure 5). To preserve the vascularization of the APS, our senior neurosurgeon (CR) opted for a TS-TU approach (Figure 6), avoiding a posterior retraction of the temporal lobe with potential venous infarction.10 Under neuronavigation, a small corticotomy was performed inside the limen insulae before going through the right uncus. We used microspatulas to retract the parenchyma in the transuncal corridor (Figure 7). We opened the external layer of the right cerebral peduncle with a vertical incision parallel to the nervous fibers. The incision was made medially to the laterally displaced PT before a piecemeal resection of the CM (Figure 8). No perioperative complication was encountered. Histopathology revealed vascular ectases with hemosiderin deposits confirming the diagnosis of CM. FIGURE 5. View largeDownload slide The dens vascularization arising from right M1 segment during the opening of the Sylvian fissure. FIGURE 5. View largeDownload slide The dens vascularization arising from right M1 segment during the opening of the Sylvian fissure. FIGURE 6. View largeDownload slide The corticotomy inside the right limiting sulcus of the insula to preserve the lateral lenticulostriates arteries. FIGURE 6. View largeDownload slide The corticotomy inside the right limiting sulcus of the insula to preserve the lateral lenticulostriates arteries. FIGURE 7. View largeDownload slide The transuncal corridor allowing an exposure of the anterior midbrain. FIGURE 7. View largeDownload slide The transuncal corridor allowing an exposure of the anterior midbrain. FIGURE 8. View largeDownload slide The image shows a complete removal of the cavernous malformation through the aforementioned transuncal approach. FIGURE 8. View largeDownload slide The image shows a complete removal of the cavernous malformation through the aforementioned transuncal approach. The patient stayed 36 h in the intensive care unit after an immediate postoperative extubation. She presented postoperatively a left hemiparesis (4/5) and central facial paresis (House Brackmann grade 3) with a right oculomotor nerve paresis (Figure 9). Cognitive and mnestic testing revealed no deficit. On the tenth postoperative day, the patient developed a Holme's tremor (HT) of the left proximal upper limb, most prominent distally. A treatment with Levodopa 375 mg per day was initiated and reached a maximum daily dose of 750 mg before regression. FIGURE 9. View largeDownload slide The patient in the postoperative course presenting a left central facial paresis (House Brackmann 3) and a right third nerve paresis. FIGURE 9. View largeDownload slide The patient in the postoperative course presenting a left central facial paresis (House Brackmann 3) and a right third nerve paresis. Three months after surgery, a complete motor recuperation was observed with an extinction of the oculomotor nerve paresis. However, the left arm tremor was still present. A cerebral MRI confirmed the GTR of the mesencephalic CM without complications (Figure 10). One year later, the patient was asymptomatic and able to work without any medication. FIGURE 10. View largeDownload slide Postoperative axial T2-weighted brain MRI showing a gross total resection of the cavernous malformation through a right transsylvian transuncal approach. FIGURE 10. View largeDownload slide Postoperative axial T2-weighted brain MRI showing a gross total resection of the cavernous malformation through a right transsylvian transuncal approach. DISCUSSION The first removal of a brainstem CM was described by Walter Dandy in 1928.2,11,12 To date, many studies have reported several surgical procedures for anterior midbrain CM resection.2,4,5,8,12,13 Subtemporal, transcallosal, and orbitozygomatic transsylvian are some of the approaches used.4,5,12,13 A trans-APS approach has also been performed by Spetzler et al14 for a thalamomesencephalic junction CM with an ischemic stroke of basal ganglia reported postoperatively. The approach of the CM is the critical point for this kind of surgery. The 2-point method described by Spetzler is used by several neurosurgical teams.4,5,9,12 This method consists of drawing a line, on an image of the brain, passing through the center of the lesion and to the point where the CM is closer to the pial surface of the brainstem. The traced line defines the best surgical route to realize. This case report concerns a resection of a right anteroparamedial mesencephalic CM. After an opening of the Sylvian fissure, the perforating arteries for the APS were visualized. To preserve this vascularization, we opted for a transuncal approach to obtain a corridor allowing a GTR of the CM without manipulation of the perforating arteries. This TS-TU approach has the advantage of giving access to the medial part of the cerebral peduncle and the interpeduncular fossa without manipulating the lenticulostriate arteries. This technique seems a sound alternative to the pretemporal approach in order to avoid the laterally displaced PT.15,16 After a brainstem CM removal, immediate postoperative course is associated with a 42% rate of neurologic morbidity.5 Clinical improvement is generally observed in the long term for 84% of these patients.5 In our case, disappearance of the symptomatology occurred 1 yr postoperatively. HT is a spectrum of abnormal movements with rest manifestation, posture worsening, and a peak of amplitude during attempted movement. HT has a delayed onset from 4 wk to 2 yr after any lesion.17,18 The mechanisms of HT are complex and poorly understood, but recent publications established that the dopaminergic nigrostriatal, the olivocerebellar, and the cerebellothalamic tracts are involved.18-23 There is also clinical evidence for an implication of the dentatorubroolivary tract—as in our case—which is a component of the rubroolivocerebellorubral loop.24 Damage to the red nucleus itself has not been proved, as the genesis of HT and lesion in the vicinity of this nucleus is necessary.17,23 Delayed onset and several damaged locations explain that the mechanism of HT results in a lesion in a complex neuronal network. In our case, a delay less than 4 wk could be explained by a more rapid offset of the compensatory mechanisms. CONCLUSION This is the first report of a TS-TU approach for the resection of an anteromedial cerebral peduncle CM. This surgical route allowed us to avoid and preserve all perforating branches to the APS. This technique appears to be another alternative for the removal of anterior midbrain CMs. Disclosure The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. A video of the surgical procedure was presented during the 2015 annual congress of the Société de Neurochirurgie de la Langue Française (SNCLF) in Paris, France on December 1st, 2015. A poster was also displayed during the 2016 annual meeting of the Belgian Society of Neurosurgery on March 19th, 2016 in Brussels, Belgium. REFERENCES 1. Chotai S, Qi S, Xu S. Prediction of outcomes for brainstem cavernous malformation. Clin Neurol Neurosurg . 2013; 115( 10): 2117- 2123. Google Scholar CrossRef Search ADS PubMed 2. Garrett M, Spetzler RF. Surgical treatment of brainstem cavernous malformations. Surg Neurol . 2009; 72( suppl 2): S3- S9. 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Nuances and technique of the pretemporal transcavernous approach to treat low-lying basilar artery aneurysms. Neurosurg Rev . 2010; 33( 2): 129- 135. Google Scholar CrossRef Search ADS PubMed 17. Maki F, Sato S, Watanabe K et al. Vim thalamotomy in a patient with Holme's tremor and palatal tremor—pathophysiological considerations. BMC Neurology . 2015; 15: 26. Google Scholar CrossRef Search ADS PubMed 18. Woo JH, Hong BY, Kim JS et al. Holmes tremor after brainstem hemorrhage, treated with levodopa. Ann Rehabil Med . 2013; 37( 4): 591- 594. Google Scholar CrossRef Search ADS PubMed 19. Martins WA, Marrone LC, Fussiger H et al. Holmes’ tremor as a delayed complication of thalamic stroke. J Clin Neurosci . 2016; 26: 158- 159. Google Scholar CrossRef Search ADS PubMed 20. Mehanna R, Jankovic J. Movement disorders in cerebrovascular disease. Lancet Neurol . 2013; 12( 6): 597- 608. Google Scholar CrossRef Search ADS PubMed 21. Yoon JH, Yong SW, Lee JS. Spontaneous disappearance of Holmes’ tremor in a patient with a midbrain cavernous hemangioma. Neurol Sci . 2015; 36( 11): 2137- 2138. Google Scholar CrossRef Search ADS PubMed 22. Espinoza Martinez JA, Arango GJ, Fonoff ET et al. Deep brain stimulation of the globus pallidus internus or ventralis intermedius nucleus of thalamus for Holmes tremor. Neurosurg Rev . 2015; 38( 4): 753- 763. Google Scholar CrossRef Search ADS PubMed 23. Ohye C, Shibazaki T, Hirai T et al. A special role of the parvocellular red nucleus in lesion-induced spontaneous tremor in monkeys. Behav Brain Res . 1988; 28( 1-2): 241- 243. Google Scholar CrossRef Search ADS PubMed 24. Shepherd GM1, Tauböll E, Bakke SJ, Nyberg-Hansen R. Midbrain tremor and hypertrophic olivary degeneration after pontine hemorrhage. Mov Disord . 1997; 12( 3): 432- 437. Google Scholar CrossRef Search ADS PubMed Comments Brainstem cavernous malformations are extremely dangerous lesions, both from a perspective of surgical risk and natural history. This case report highlights the difficulty of the surgical procedure and the creativity of the surgeon required to deal with the perceived limitation of the perforator anatomy in the sylvian fissure. In this case, the midbrain lesion was approached through the uncus rather than retracting the uncus, as the surgeons felt that injury to the lenticulostriate arteries would be less likely than in a pure transsylvian route. The surgical resection was complete and the ultimate clinical outcome was excellent. As demonstrated, injury to the uncus unilaterally is generally well tolerated, and a trans-uncal approach to the midbrain can be viewed as a viable alternative when anatomically expedient. Robert Solomon New York, New York I feel that in a patient with a cavernous hemangioma of the anterolateral part of the midbrain such as this one, the use of an orbitozygomatic osteotomy, with wide opening of the sylvian fissure can obviate the need for the removal of the uncus. The space provided by that approach is wide enough to expose the midbrain without brain resection. It may be necessary to divide the superficial middle cerebral vein draining into the sphenoparietal sinus with that approach. Laligam N. Sekhar Seattle, Washington Cavernous malformations located in the ventral midbrain present a particular microsurgical challenge. Although in theory a standard trans-Sylvian or even subtemporal approach should provide adequate access, in practice the exposure provided by these approaches is often too narrow. The trans-Sylvian/trans-uncal approach described in this paper is an attractive alternative to reach these lesions. It has the advantages of minimizing manipulation of the lenticulostriate perforators, minimizing retraction on the anterior perforated substance, and providing a wider corridor. Rafael J. Tamargo Baltimore, Maryland Copyright © 2017 by the Congress of Neurological Surgeons
Operative Neurosurgery – Oxford University Press
Published: Mar 1, 2018
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