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Clinical case
Unexpected ruptured aneurysm during posterior fossa surgery Rupture inattendue d’anévrisme pendant une chirurgie de fosse postérieure L. Chenin ∗ , C. Capel , H. N’Da , M. Lefranc , J. Peltier Department of Neurosurgery, Amiens Nord Hospital, Jules Verne University, France
a r t i c l e
i n f o
Article history: Received 21 November 2013 Received in revised form 13 January 2014 Accepted 19 February 2014 Available online xxx Keywords: Posterior fossa surgery Cerebellar metastasis Peroperative complication Aneurysm Superior cerebellar artery
a b s t r a c t Background and importance. – Surgery is the recommended treatment for unique significant cerebellar metastasis, particularly in cases of hydrocephalus. Complications of posterior fossa surgery are associated with high risk of morbidity and mortality. We present a unique case of unexpected peroperative rupture of a cerebellar superior artery aneurysm during posterior fossa surgery. Clinical presentation. – During posterior cranial fossa surgery, severe arterial bleeding occurred in front of the medulla oblongata. Immediate postoperative computed tomographic (CT) angiography revealed a fusiform aneurysm from a distal branch of the left superior cerebellar artery. Conclusion. – To our knowledge, this is the first reported operative case of unexpected infratentorial ruptured aneurysm during posterior fossa surgery. © 2014 Published by Elsevier Masson SAS.
r é s u m é Mots clés : Fosse cérébrale postérieure Métastase cérébelleuse Complication peropératoire Anévrisme Artère cérébelleuse supérieure
Introduction. – En règle générale, le traitement de la lésion métastatique cérébelleuse unique est l’exérèse, surtout si cette lésion est de gros volume ou en cas d’hydrocéphalie sus-jacente. Ce type de chirurgie associe un risque important de morbidité et de mortalité per- et postopératoire. Nous présentons un cas unique de rupture inattendue peropératoire d’un anévrisme de l’artère cérébelleuse supérieure pendant une exérèse de métastase de fosse postérieure. Presentation clinique. – Au cours de l’exérèse d’une métastase cérébelleuse de cancer du sein, un important saignement artériel survenait à la face ventrale de la moelle allongée. L’angioscanner cérébral postopératoire immédiat montrait un anévrisme fusiforme distal d’une branche de l’artère cérébelleuse supérieure gauche. Conclusion. – D’après la littérature, il s’agit du premier cas décrit de rupture inattendue d’anévrisme infratentoriel pendant une chirurgie d’exérèse de tumeur de fosse postérieure. © 2014 Publie´ par Elsevier Masson SAS.
1. Introduction Brain metastases often have a poor overall prognosis, primarily if they are located in the posterior cerebral fossa, due to the risk of acute hydrocephalus [1]. Surgical resection must be considered as the first option as it increases the median survival time for the patients who are clinically eligible [2].
∗ Corresponding author. Service de neurochirurgie, centre hospitalier universitaire d’Amiens, place Victor-Pauchet, 80054 Amiens cedex 1, France. E-mail address: [email protected] (L. Chenin).
Complications during posterior fossa surgery have been described and are well known: bradycardia and hypotension by direct stimulation of the trigeminal nerve [3,4] or by surgical compression of the medulla oblongata [5]; gas embolism following hydrogen peroxide irrigation of the surgical field [6] or reverse brain herniation by an intraventricular shunt [7]. Early postoperative complications for this type of surgery include cerebrospinal fluid leakage, haematoma and seizures [8]. Haematoma is associated with a high risk of morbidity and mortality. We present a unique case of an aneurysmal subarachnoid haemorrhage during posterior fossa surgery caused by an unknown ruptured superior cerebellar artery aneurysm.
http://dx.doi.org/10.1016/j.neuchi.2014.02.007 0028-3770/© 2014 Published by Elsevier Masson SAS.
Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
G Model NEUCHI-622; No. of Pages 4
ARTICLE IN PRESS L. Chenin et al. / Neurochirurgie xxx (2014) xxx–xxx
2
Fig. 1. Sagittal MR imaging (1A) and axial (1B), T1 sequence with gadolinium enhancement, showing an unique cerebellar tumour. Note: a small supracerebellar infratentorial vein behind the tumour and in front of the torcular herophili. IRM séquence T1 avec gadolinium, coupes sagittale (1A) et axiale (1B) montrant la tumeur cérébelleuse. Notez : une petite veine supracérébelleuse infratentorielle est située entre la tumeur et le torcular.
2. Clinical presentation We reported the case of a 62-year-old woman, who had been monitored for a left breast lobular carcinoma over a 4-year period, with liver, pulmonary and bone metastasis. The lesions of the liver, lung and bone remained stable under tamoxifen/herceptin administration. She also received radiotherapy for both rib and pelvic pains. She had been experiencing a gait disturbance for the previous several weeks. Clinical examination revealed a kinetic and static cerebellar syndrome. Cerebral MRI showed an expansive cerebellar lesion on contrast enhancement and a perilesional oedema. This tumour extended from the left middle cerebellar peduncle and was adherent to the cerebelli tentorium (Fig. 1). Due to this unique symptomatic metastatic cerebellar tumour, surgery was decided. The operation was performed in the prone position, neck in slight flexion. A left paramedian suboccipital craniectomy permitted a tumour resection until the fourth ventricle under microscopic magnification. Suddenly, a haemorrhage arising from the left laterobulbar cistern occurred. The colour of the bleeding was red. There was no evidence of a venous cause (absence of variation such as oblique occipital sinus). We did not have access to the collicular cistern or ambient cistern to view where the bleeding exactly occurred. Haemostasis was difficult. We used a haemostatic matrix device FLOSEAL® and flushing with Ringer’s Lactate solution to stop the arterial bleeding. Just after surgery, the patient unfortunately experienced a left eye mydriasis. She immediately had a CT scan that showed a subarachnoid haemorrhage in the basal cisterns, particularly in the cisterna interpeduncularis (Fig. 2). During this examination, an associated CT angiography highlighted a dysplastic formation of the distal branch of the left cerebellar superior artery (SCA), its neck measured 2.2 mm. It appeared to be a fusiform aneurysm (Fig. 3). There was an associated obstructive hydrocephalus, because of cisterna magna fourth ventricle bleeding contamination. There was no other associated malformation, except for a fenestration at the origin of the homolateral superior artery. Due to the mesencephalic topography of the bleeding and immediate postoperative left mydriasis, we proposed no surgical evacuation of the posterior fossa haematoma or external ventricle drainage to prevent rebleeding. The patient was subsequently transferred to the neurosurgery intensive care unit but died 4 days later.
Fig. 2. Axial CT scan without contrast enhancement after surgery showing a subarachnoid haemorrhage in the basal cisterns (1: cisterna interpeduncularis). Scanner cérébral postopératoire sans injection, montrant l’hémorragie sousarachnoïdienne dans les citernes de la base (1 : citerne interpédonculaire).
3. Discussion The main complications of posterior fossa craniectomy are oedema, haematoma, cerebrospinal fluid fistula and meningocele [9]. A retrospective study of 726 patients who underwent this type of surgery showed that 13 patients had seizures (1.8%) in the early postoperative period (1 day to 2 weeks), primarily due to hydrocephaly [8]. Remote supratentorial intracerebral haemorrhage has also been described due to persistent elevation of blood pressure during this stage [10]. In the literature, there is no reported case of unexpected peroperative subarachnoidal haemorrhage during surgery for a cerebellar tumour. One case was described where a 4-month-old child presented with obstructive hydrocephalus on a huge mass occupying the entire posterior cranial fossa [11]. The patient died 6 hours after
Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
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ARTICLE IN PRESS L. Chenin et al. / Neurochirurgie xxx (2014) xxx–xxx
Fig. 3. CT angiogram with volume rendering, centered on the aneurysm (arrow), left view: basilar artery (1), left cerebral posterior artery (2), left cerebellar superior artery, with a fenestration at the origin (3). Angioscanner cérébral avec reconstruction 3D, centré sur l’anévrisme (flèche), vue gauche : artère basilaire (1), artère cérébrale postérieure gauche (2), artère cérébelleuse supérieure gauche fenêtrée à son origine (3).
the insertion of a ventriculoperitoneal shunt. The autopsy revealed a rupture of a giant posterior inferior cerebellar artery aneurysm. According to these authors, the mechanism of this rupture was probably the release of the tamponade effect related to the CSF during the shunt operation or the brutal variation of the cerebral blood flow following ventricle opening, even if the usual width of giant intracranial aneurysm was thicker than small aneurysms. Recently, an intraoperative subarachnoid haemorrhage during Chiari decompression was reported [12]. Initial cerebral angiography was normal, but the follow-up on day 12 revealed a small aneurysm on the posterior inferior cerebellar artery. These authors hypothesized that the decompression could have significantly increased the caudal flow of CSF around the spinal region, precipitating the aneurysm’s rupture. In our case, the mechanism of the aneurysmal rupture is unclear. It may have been a brief decrease in the intracranial pressure due to the opening of the fourth ventricle or a tear of the cerebellar artery along the free edge of dura mater of tentorium cerebelli. Although the distal portion of the SCA produces a cerebellomesencephalic segment [13], we do not think that this fusiform aneurysm could have been caused by the dissection of the metastasis as the cranial pole of the tumour was located 2 cm below the ambient cistern where the SCA courses. Furthermore, we have no other explanation for the cisternal peribulbar haemorrhage other than the bleeding contamination from the cisterna interpeduncularis. Moreover, we did not have access to the collicular cistern or ambient cistern during the intervention. Distal aneurysm of the SCA is unusual and represents 0.2 % of all cerebral aneurysms. Fusiform aneurysmal dilatation of the distal SCA is very rare, and has been reported in 9 cases [14]. They have been classified as dissecting aneurysms depending on the CT angiogram. If an intraluminal thrombus was observed, it was a fusiform rather than a dissecting aneurysm. In our case, we did not perform a cerebral angiography because of the good quality of the CT angiogram and the severity of postoperative clinical examination, avoiding any further action.
3
In the literature, causes of a SCA aneurysm have been discussed. Some authors have hypothesized a traumatism of the SCA on the free edge of the tentorium [15], creating a dissecting aneurysm of this artery. Other authors have described a case of cerebellar aneurysm following stereotactic gamma knife surgery for an acoustic neuroma [16]. Several types of complications may occur during the posterior fossa approach. Brain swelling before opening the dura mater could be suggested by subdural intracranial pressure [17], thereby classifying high-risk patients. Posterior reversible encephalopathy syndrome has been reported during cerebellar tumour resection [18] resulting in severe hypertension and typical immediate postoperative MRI images with an abnormal FLAIR signal in both occipital and temporal lobes. This situation requires urgent and appropriate medical treatment. Skull fractures due to the penetration of the head holder pin [19] could be prevented by a careful installation of the patient and a thorough analysis of the skull, especially in children. Furthermore, complications related to positioning were studied in 260 patients who underwent a posterior fossa craniectomy [20]. The detected venous air embolism was significantly more severe in the sitting position than in the prone position. Cranial nerve functions were better preserved in the sitting position. Moreover, quadriplegia is a common complication in the sitting position because of the neck’s hyperflexion and has rarely been reported in the prone position [21]. Finally, seizures after posterior fossa surgery are significantly more frequent in the sitting position than in the lateral or prone position [22].
4. Conclusion In planning and performing posterior fossa surgery, special emphasis has to be put on the course of the cerebellar arteries. Thus, a thorough study of the MRI is highly recommended before approaching infratentorial tumour surgery.
Disclosure of interest The authors declare that they have no conflicts of interest concerning this article.
References [1] Fujimaki T. Surgical treatment of brain metastasis. Int J Clin Oncol 2005;10:74–80. [2] Yoshida S, Takahashi H. Cerebellar metastases in patients with cancer. Surg Neurol 2009;71:184–7 [discussion 187]. [3] Agrawal A, Timothy J, Cincu R, Agarwal T, Waghmare LB. Bradycardia in neurosurgery. Clin Neurol Neurosurg 2008;110:321–7. [4] Usami K, Kamada K, Kunii N, Tsujihara H, Yamada Y, Saito N. Transient asystole during surgery for posterior fossa meningioma caused by activation of the trigeminocardiac reflex: three case reports. Neurol Med Chir (Tokyo) 2010;50:339–42. [5] Endo T, Sato K, Takahashi T, Kato M. Acute hypotension and bradycardia by medulla oblongata compression in spinal surgery. J Neurosurg Anesthesiol 2001;13:310–3. [6] Dubey PK, Singh AK. Venous oxygen embolism due to hydrogen peroxide irrigation during posterior fossa surgery. J Neurosurg Anesthesiol 2000;12:54–6. [7] Prabhakar H, Umesh G, Chouhan RS, Bithal PK. Reverse brain herniation during posterior fossa surgery. J Neurosurg Anesthesiol 2003;15:267–9. [8] Lee ST, Lui TN, Chang CN, Cheng WC. Early postoperative seizures after posterior fossa surgery. J Neurosurg 1990;73:541–4. [9] Greenberg MS. Handbook of neurosurgery. Seventh edition Thieme: University of South Florida, Tampa; 2010. [10] Haines SJ, Maroon JC, Jannetta PJ. Supratentorial intracerebral hemorrhage following posterior fossa surgery. J Neurosurg 1978;49:881–6. [11] Desai K, Nadkarni T, Muzumdar D, Goel A. Rupture of a giant posterior inferior cerebellar artery aneurysm in an infant following a ventriculoperitoneal shunt – Case report. Neurol Med Chir (Tokyo) 2001;41:127–30.
Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
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[12] Sorour M, Bowers CA, Couldwell WT. Intraoperative aneurysmal subarachnoid hemorrhage after rupture of a previously undiagnosed intracranial aneurysm during Chiari decompression. J Clin Neurosci 2013. [13] Rodríguez-Hernández A, Rhoton Jr AL, Lawton MT. Segmental anatomy of cerebellar arteries: a proposed nomenclature. Laboratory investigation. J Neurosurg 2011;115:387–97. [14] Atalay B, Altinors N, Yilmaz C, Caner H, Ozger O. Fusiform aneurysm of the superior cerebellar artery: short review article. Acta Neurochir (Wien) 2007;149:291–4 [discussion 294]. [15] Proust F, Callonec F, Bellow F, Laquerriere A, Hannequin D, Fréger P. Tentorial edge traumatic aneurysm of the superior cerebellar artery. Case report. J Neurosurg 1997;87:950–4. [16] Takao T, Fukuda M, Kawaguchi T, Nishino K, Ito Y, Tanaka R. Ruptured intracranial aneurysm following gamma knife surgery for acoustic neuroma. Acta Neurochir (Wien) 2006;148:1317–8 [discussion 1318].
[17] Iversen BN, Rasmussen M, Cold GE. The relationship between intracranial pressure and the degree of brain swelling in patients subjected to infratentorial surgery. Acta Neurochir (Wien) 2008;150:337–44 [discussion 344]. [18] Patel AJ, Fox BD, Fulkerson DH, Yallampalli S, Illner A, Whitehead WE, et al. Posterior reversible encephalopathy syndrome during posterior fossa tumor resection in a child. J Neurosurg Pediatr 2010;6:377–80. [19] Martínez-Lage JF, Almagro M-J, Serrano C, Mena L. Depressed skull fracture by a three-pin head holder: a case illustration. Childs Nerv Syst 2011;27:163–5. [20] Rath GP, Bithal PK, Chaturvedi A, Dash HH. Complications related to positioning in posterior fossa craniectomy. J Clin Neurosci 2007;14:520–5. [21] Rau C-S, Liang C-L, Lui C-C, Lee T-C, Lu K. Quadriplegia in a patient who underwent posterior fossa surgery in the prone position. Case report. J Neurosurg 2002;96:101–3. [22] Suri A, Mahapatra AK, Bithal P. Seizures following posterior fossa surgery. Br J Neurosurg 1998;12:41–4.
Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
ARTICLE IN PRESS
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Neurochirurgie xxx (2014) xxx–xxx
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Clinical case
Unexpected ruptured aneurysm during posterior fossa surgery Rupture inattendue d’anévrisme pendant une chirurgie de fosse postérieure L. Chenin ∗ , C. Capel , H. N’Da , M. Lefranc , J. Peltier Department of Neurosurgery, Amiens Nord Hospital, Jules Verne University, France
a r t i c l e
i n f o
Article history: Received 21 November 2013 Received in revised form 13 January 2014 Accepted 19 February 2014 Available online xxx Keywords: Posterior fossa surgery Cerebellar metastasis Peroperative complication Aneurysm Superior cerebellar artery
a b s t r a c t Background and importance. – Surgery is the recommended treatment for unique significant cerebellar metastasis, particularly in cases of hydrocephalus. Complications of posterior fossa surgery are associated with high risk of morbidity and mortality. We present a unique case of unexpected peroperative rupture of a cerebellar superior artery aneurysm during posterior fossa surgery. Clinical presentation. – During posterior cranial fossa surgery, severe arterial bleeding occurred in front of the medulla oblongata. Immediate postoperative computed tomographic (CT) angiography revealed a fusiform aneurysm from a distal branch of the left superior cerebellar artery. Conclusion. – To our knowledge, this is the first reported operative case of unexpected infratentorial ruptured aneurysm during posterior fossa surgery. © 2014 Published by Elsevier Masson SAS.
r é s u m é Mots clés : Fosse cérébrale postérieure Métastase cérébelleuse Complication peropératoire Anévrisme Artère cérébelleuse supérieure
Introduction. – En règle générale, le traitement de la lésion métastatique cérébelleuse unique est l’exérèse, surtout si cette lésion est de gros volume ou en cas d’hydrocéphalie sus-jacente. Ce type de chirurgie associe un risque important de morbidité et de mortalité per- et postopératoire. Nous présentons un cas unique de rupture inattendue peropératoire d’un anévrisme de l’artère cérébelleuse supérieure pendant une exérèse de métastase de fosse postérieure. Presentation clinique. – Au cours de l’exérèse d’une métastase cérébelleuse de cancer du sein, un important saignement artériel survenait à la face ventrale de la moelle allongée. L’angioscanner cérébral postopératoire immédiat montrait un anévrisme fusiforme distal d’une branche de l’artère cérébelleuse supérieure gauche. Conclusion. – D’après la littérature, il s’agit du premier cas décrit de rupture inattendue d’anévrisme infratentoriel pendant une chirurgie d’exérèse de tumeur de fosse postérieure. © 2014 Publie´ par Elsevier Masson SAS.
1. Introduction Brain metastases often have a poor overall prognosis, primarily if they are located in the posterior cerebral fossa, due to the risk of acute hydrocephalus [1]. Surgical resection must be considered as the first option as it increases the median survival time for the patients who are clinically eligible [2].
∗ Corresponding author. Service de neurochirurgie, centre hospitalier universitaire d’Amiens, place Victor-Pauchet, 80054 Amiens cedex 1, France. E-mail address: [email protected] (L. Chenin).
Complications during posterior fossa surgery have been described and are well known: bradycardia and hypotension by direct stimulation of the trigeminal nerve [3,4] or by surgical compression of the medulla oblongata [5]; gas embolism following hydrogen peroxide irrigation of the surgical field [6] or reverse brain herniation by an intraventricular shunt [7]. Early postoperative complications for this type of surgery include cerebrospinal fluid leakage, haematoma and seizures [8]. Haematoma is associated with a high risk of morbidity and mortality. We present a unique case of an aneurysmal subarachnoid haemorrhage during posterior fossa surgery caused by an unknown ruptured superior cerebellar artery aneurysm.
http://dx.doi.org/10.1016/j.neuchi.2014.02.007 0028-3770/© 2014 Published by Elsevier Masson SAS.
Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
G Model NEUCHI-622; No. of Pages 4
ARTICLE IN PRESS L. Chenin et al. / Neurochirurgie xxx (2014) xxx–xxx
2
Fig. 1. Sagittal MR imaging (1A) and axial (1B), T1 sequence with gadolinium enhancement, showing an unique cerebellar tumour. Note: a small supracerebellar infratentorial vein behind the tumour and in front of the torcular herophili. IRM séquence T1 avec gadolinium, coupes sagittale (1A) et axiale (1B) montrant la tumeur cérébelleuse. Notez : une petite veine supracérébelleuse infratentorielle est située entre la tumeur et le torcular.
2. Clinical presentation We reported the case of a 62-year-old woman, who had been monitored for a left breast lobular carcinoma over a 4-year period, with liver, pulmonary and bone metastasis. The lesions of the liver, lung and bone remained stable under tamoxifen/herceptin administration. She also received radiotherapy for both rib and pelvic pains. She had been experiencing a gait disturbance for the previous several weeks. Clinical examination revealed a kinetic and static cerebellar syndrome. Cerebral MRI showed an expansive cerebellar lesion on contrast enhancement and a perilesional oedema. This tumour extended from the left middle cerebellar peduncle and was adherent to the cerebelli tentorium (Fig. 1). Due to this unique symptomatic metastatic cerebellar tumour, surgery was decided. The operation was performed in the prone position, neck in slight flexion. A left paramedian suboccipital craniectomy permitted a tumour resection until the fourth ventricle under microscopic magnification. Suddenly, a haemorrhage arising from the left laterobulbar cistern occurred. The colour of the bleeding was red. There was no evidence of a venous cause (absence of variation such as oblique occipital sinus). We did not have access to the collicular cistern or ambient cistern to view where the bleeding exactly occurred. Haemostasis was difficult. We used a haemostatic matrix device FLOSEAL® and flushing with Ringer’s Lactate solution to stop the arterial bleeding. Just after surgery, the patient unfortunately experienced a left eye mydriasis. She immediately had a CT scan that showed a subarachnoid haemorrhage in the basal cisterns, particularly in the cisterna interpeduncularis (Fig. 2). During this examination, an associated CT angiography highlighted a dysplastic formation of the distal branch of the left cerebellar superior artery (SCA), its neck measured 2.2 mm. It appeared to be a fusiform aneurysm (Fig. 3). There was an associated obstructive hydrocephalus, because of cisterna magna fourth ventricle bleeding contamination. There was no other associated malformation, except for a fenestration at the origin of the homolateral superior artery. Due to the mesencephalic topography of the bleeding and immediate postoperative left mydriasis, we proposed no surgical evacuation of the posterior fossa haematoma or external ventricle drainage to prevent rebleeding. The patient was subsequently transferred to the neurosurgery intensive care unit but died 4 days later.
Fig. 2. Axial CT scan without contrast enhancement after surgery showing a subarachnoid haemorrhage in the basal cisterns (1: cisterna interpeduncularis). Scanner cérébral postopératoire sans injection, montrant l’hémorragie sousarachnoïdienne dans les citernes de la base (1 : citerne interpédonculaire).
3. Discussion The main complications of posterior fossa craniectomy are oedema, haematoma, cerebrospinal fluid fistula and meningocele [9]. A retrospective study of 726 patients who underwent this type of surgery showed that 13 patients had seizures (1.8%) in the early postoperative period (1 day to 2 weeks), primarily due to hydrocephaly [8]. Remote supratentorial intracerebral haemorrhage has also been described due to persistent elevation of blood pressure during this stage [10]. In the literature, there is no reported case of unexpected peroperative subarachnoidal haemorrhage during surgery for a cerebellar tumour. One case was described where a 4-month-old child presented with obstructive hydrocephalus on a huge mass occupying the entire posterior cranial fossa [11]. The patient died 6 hours after
Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
G Model NEUCHI-622; No. of Pages 4
ARTICLE IN PRESS L. Chenin et al. / Neurochirurgie xxx (2014) xxx–xxx
Fig. 3. CT angiogram with volume rendering, centered on the aneurysm (arrow), left view: basilar artery (1), left cerebral posterior artery (2), left cerebellar superior artery, with a fenestration at the origin (3). Angioscanner cérébral avec reconstruction 3D, centré sur l’anévrisme (flèche), vue gauche : artère basilaire (1), artère cérébrale postérieure gauche (2), artère cérébelleuse supérieure gauche fenêtrée à son origine (3).
the insertion of a ventriculoperitoneal shunt. The autopsy revealed a rupture of a giant posterior inferior cerebellar artery aneurysm. According to these authors, the mechanism of this rupture was probably the release of the tamponade effect related to the CSF during the shunt operation or the brutal variation of the cerebral blood flow following ventricle opening, even if the usual width of giant intracranial aneurysm was thicker than small aneurysms. Recently, an intraoperative subarachnoid haemorrhage during Chiari decompression was reported [12]. Initial cerebral angiography was normal, but the follow-up on day 12 revealed a small aneurysm on the posterior inferior cerebellar artery. These authors hypothesized that the decompression could have significantly increased the caudal flow of CSF around the spinal region, precipitating the aneurysm’s rupture. In our case, the mechanism of the aneurysmal rupture is unclear. It may have been a brief decrease in the intracranial pressure due to the opening of the fourth ventricle or a tear of the cerebellar artery along the free edge of dura mater of tentorium cerebelli. Although the distal portion of the SCA produces a cerebellomesencephalic segment [13], we do not think that this fusiform aneurysm could have been caused by the dissection of the metastasis as the cranial pole of the tumour was located 2 cm below the ambient cistern where the SCA courses. Furthermore, we have no other explanation for the cisternal peribulbar haemorrhage other than the bleeding contamination from the cisterna interpeduncularis. Moreover, we did not have access to the collicular cistern or ambient cistern during the intervention. Distal aneurysm of the SCA is unusual and represents 0.2 % of all cerebral aneurysms. Fusiform aneurysmal dilatation of the distal SCA is very rare, and has been reported in 9 cases [14]. They have been classified as dissecting aneurysms depending on the CT angiogram. If an intraluminal thrombus was observed, it was a fusiform rather than a dissecting aneurysm. In our case, we did not perform a cerebral angiography because of the good quality of the CT angiogram and the severity of postoperative clinical examination, avoiding any further action.
3
In the literature, causes of a SCA aneurysm have been discussed. Some authors have hypothesized a traumatism of the SCA on the free edge of the tentorium [15], creating a dissecting aneurysm of this artery. Other authors have described a case of cerebellar aneurysm following stereotactic gamma knife surgery for an acoustic neuroma [16]. Several types of complications may occur during the posterior fossa approach. Brain swelling before opening the dura mater could be suggested by subdural intracranial pressure [17], thereby classifying high-risk patients. Posterior reversible encephalopathy syndrome has been reported during cerebellar tumour resection [18] resulting in severe hypertension and typical immediate postoperative MRI images with an abnormal FLAIR signal in both occipital and temporal lobes. This situation requires urgent and appropriate medical treatment. Skull fractures due to the penetration of the head holder pin [19] could be prevented by a careful installation of the patient and a thorough analysis of the skull, especially in children. Furthermore, complications related to positioning were studied in 260 patients who underwent a posterior fossa craniectomy [20]. The detected venous air embolism was significantly more severe in the sitting position than in the prone position. Cranial nerve functions were better preserved in the sitting position. Moreover, quadriplegia is a common complication in the sitting position because of the neck’s hyperflexion and has rarely been reported in the prone position [21]. Finally, seizures after posterior fossa surgery are significantly more frequent in the sitting position than in the lateral or prone position [22].
4. Conclusion In planning and performing posterior fossa surgery, special emphasis has to be put on the course of the cerebellar arteries. Thus, a thorough study of the MRI is highly recommended before approaching infratentorial tumour surgery.
Disclosure of interest The authors declare that they have no conflicts of interest concerning this article.
References [1] Fujimaki T. Surgical treatment of brain metastasis. Int J Clin Oncol 2005;10:74–80. [2] Yoshida S, Takahashi H. Cerebellar metastases in patients with cancer. Surg Neurol 2009;71:184–7 [discussion 187]. [3] Agrawal A, Timothy J, Cincu R, Agarwal T, Waghmare LB. Bradycardia in neurosurgery. Clin Neurol Neurosurg 2008;110:321–7. [4] Usami K, Kamada K, Kunii N, Tsujihara H, Yamada Y, Saito N. Transient asystole during surgery for posterior fossa meningioma caused by activation of the trigeminocardiac reflex: three case reports. Neurol Med Chir (Tokyo) 2010;50:339–42. [5] Endo T, Sato K, Takahashi T, Kato M. Acute hypotension and bradycardia by medulla oblongata compression in spinal surgery. J Neurosurg Anesthesiol 2001;13:310–3. [6] Dubey PK, Singh AK. Venous oxygen embolism due to hydrogen peroxide irrigation during posterior fossa surgery. J Neurosurg Anesthesiol 2000;12:54–6. [7] Prabhakar H, Umesh G, Chouhan RS, Bithal PK. Reverse brain herniation during posterior fossa surgery. J Neurosurg Anesthesiol 2003;15:267–9. [8] Lee ST, Lui TN, Chang CN, Cheng WC. Early postoperative seizures after posterior fossa surgery. J Neurosurg 1990;73:541–4. [9] Greenberg MS. Handbook of neurosurgery. Seventh edition Thieme: University of South Florida, Tampa; 2010. [10] Haines SJ, Maroon JC, Jannetta PJ. Supratentorial intracerebral hemorrhage following posterior fossa surgery. J Neurosurg 1978;49:881–6. [11] Desai K, Nadkarni T, Muzumdar D, Goel A. Rupture of a giant posterior inferior cerebellar artery aneurysm in an infant following a ventriculoperitoneal shunt – Case report. Neurol Med Chir (Tokyo) 2001;41:127–30.
Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
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Please cite this article in press as: Chenin L, et al. Unexpected ruptured aneurysm during posterior fossa surgery. Neurochirurgie (2014), http://dx.doi.org/10.1016/j.neuchi.2014.02.007
