Cerebellar mutism in adults after posterior fossa surgery: a report of 2 cases

BACKGROUND: Mutism has been associated with injury to midline cerebellar structures secondary to degenerative disease, tumors, hemorrhage, or surgery. Typically, cerebellar mutism syndrome (CMS) has been seen in children and only rarely described in adults after surgery of the posterior fossa. This syndrome typically arises 48 hours after the initiating event and resolves approximately 7 to 8 weeks later. Characteristics of CMS include complete absence of speech without impaired consciousness, other cranial nerve deficits, or long tract signs. CASE DESCRIPTION: The authors report on 2 patients each of whom developed cerebellar mutism after tumor resection using a posterior fossa approach. The first patient underwent gross total resection of a pineal region tumor via a supracerebellar approach. The second patient underwent posterior fossa decompression for a left cerebellar hemispheric renal cell carcinoma metastasis with adjacent hemorrhage. One patient displayed a variant of cerebellar mutism with severe ataxic dysarthria without complete absence of speech, whereas the other demonstrated frank mutism. After neuroimaging studies confirmed the absence of a surgically treatable postoperative cause for the patients' symptoms, they were managed in a supportive fashion (eg, speech therapy) and improved within 3.5 months and 1 year, respectively. CONCLUSION: It is paramount that neurosurgeons be aware of cerebellar mutism with regard to its very rare occurrence in adults, its time of onset, and typical self-limiting course.     

Unexpected ruptured aneurysm during posterior fossa surgery

Background and importanceSurgery 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 presentationDuring 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.ConclusionTo our knowledge, this is the first reported operative case of unexpected infratentorial ruptured aneurysm during posterior fossa surgery.     

Intracranial pressure monitoring in the posterior fossa: a preliminary report

Direct therapeutic drainage and intracranial pressure monitoring from the posterior fossa has never been accepted in neurosurgical practice. Potential complications including cerebrospinal fluid leak, cranial nerve palsies, and brain-stem irritation have been a major deterrent. The authors placed a catheter for pressure monitoring in the posterior fossa of 20 patients in the course of posterior fossa surgery: 14 patients with acoustic schwannomas, four with posterior fossa meningiomas, one with cerebellar hemangioblastoma, and one with a solitary cerebellar metastatic lesion. A Richmond bolt was also placed in the frontal area. Continuous monitoring of the supratentorial and infratentorial compartments was performed for 48 hours. During the first 12 hours the posterior fossa pressure was 50% greater than that of the supratentorial space in all patients (p less than 0.01). Over the next 12 hours the supratentorial pressure was 10% and 15% higher than the posterior fossa pressures in all patients, and by 48 hours of monitoring the pressures had equilibrated. There was no mortality or morbidity referable to insertion of the posterior fossa catheter. The conclusions drawn from this study are that: 1) direct monitoring and drainage of the posterior fossa is safe and effective; and 2) within the early postoperative period, the supratentorial pressures failed to reflect what is taking place within the posterior fossa. The implications and advantages of direct posterior fossa monitoring in the postoperative patient are discussed.     

Microsurgical anatomy and surgical exposure of the cerebellar peduncles

A better understanding of the surgical anatomy of the cerebellar peduncles in different surgical approaches and their relationship with other neural structures are delineated through cadaveric dissections. We aimed to revisit the surgical anatomy of the cerebellar peduncles to describe their courses along the brain stem and the cerebellum and revise their segmental classification in surgical areas exposed through different approaches. Stepwise fiber microdissection was performed along the cerebellar tentorial and suboccipital surfaces. Multiple surgical approaches in each of the cerebellar peduncles were compared in eight silicone-injected cadaveric whole heads to evaluate the peduncular exposure areas. From a neurosurgical point of view, the middle cerebellar peduncle (MCP) was divided into a proximal cisternal and a distal intracerebellar segments; the inferior cerebellar peduncle (ICP) into a ventricular segment followed by a posterior curve and a subsequent intracerebellar segment; the superior cerebellar peduncle (SCP) into an initial congregated, an intermediate intraventricular, and a distal intramesencephalic segment. Retrosigmoid and anterior petrosectomy approaches exposed the junction of the MCP segments; telovelar, supratonsillar, and lateral ICP approaches each reached different segments of ICP; paramedian supracerebellar infratentorial, suboccipital transtentorial, and combined posterior transpetrosal approaches displayed the predecussation SCP within the cerbellomesencephalic fissure, whereas the telovelar approach revealed the intraventricular SCP within the superolateral recess of the fourth ventricle. Better understanding of the microsurgical anatomy of the cerebellar peduncles in various surgical approaches and their exposure limits constitute the most critical aspect for the prevention of surgical morbidity during surgery in and around the pons and the upper medulla. Our findings help in evaluating radiological data and planning an operative procedure for cerebellar peduncles.

     

Venous angiomas of the posterior fossa should be considered as anomalous venous drainage

Venous angioma of the posterior fossa has been described, and the existing literature has been reviewed. The patient presented had a venous angioma located in the pons, and both cerebellar hemispheres and was drained by an enlarged and anatomically anomalous vein within the fourth ventricle. The patient had a "cough headache" and later had signs of cerebellar involvement. A surgical attempt at collapsing the anomalous vein resulted in death in the immediate postoperative period due to venous infarction of the brain stem and cerebellum. Emphasis has been given to the following: 1. "Cough Headache" can be a presenting feature for venous angiomas of the posterior fossa. 2. Venous angiomas of the posterior fossa are developmental anatomic anomalies with enlargement of certain venous structures as a result of inadequate alternative venous drainage. 3. The enlarged vein, which is the pathognomonic feature of venous angiomas, serves a vital function in drainage of blood from structures in the posterior fossa as the usual drainage pathways are inadequate or absent. 4. Operative intervention aimed at resection or collapse of such large veins, which has been successful in treatment of venous angiomas of the frontal lobe, can be disastrous in the treatment of those lesions occurring in the posterior fossa.     

Primary cerebellar germinomas of the posterior fossa

Primary cerebellar germinomas, in the absence of germ-cell tumours outside the nervous system or elsewhere in the cranial cavity and CSF pathways, are exceptional; only two previous cases have been reported in the literature. Two personal observations are described from our 20-year records of intra-axial posterior fossa tumours. The patients were a 32-year-old man and a 17-year-old woman with a clinical history of posterior fossa tumour, studied by computed tomography. The first patient with slight cerebellar signs had a small right hemispheric cerebellar tumour, and the other had a left cerebellar mass with hydrocephalus and progressive intracranial hypertension. Both were treated by tumour removal and irradiation to the whole posterior fossa. The survival times were 58 and 49 months, respectively. The diagnosis of primary cerebellar germinoma cannot be suspected before pathological confirmation. The clinical, neuroradiological and surgical findings are non-specific and quite similar to those of other malignant cerebellar tumours, such as anaplastic gliomas or metastases. Surgery and radiotherapy ensure adequate tumour control in the early stages; cases of recurrence or disseminated disease may be treated by irradiation and chemotherapy.     

A case of cerebellar hematoma due to venous angioma presenting trigeminal dysfunction

With regard to the natural history of venous angioma, the risk of hemorrhage is reported to be relatively higher if the lesion exists in the posterior fossa. However a recent report of 100 cases of venous angioma concluded that the risk of hemorrhage was low, being only 0.22%/year. Although the true rate of hemorrhage is uncertain, we have encountered case of cerebellar hematoma due to venous angioma in the posterior fossa where the patient presented with trigeminal dysfunction and cerebellar ataxia, without any history of hypertension. We considered that venous angioma in the posterior fossa might cause cerebellar hemorrhage. After removal of the hematoma, the patient's symptoms were resolved. In the posterior fossa, a relatively higher volume of venous blood would cause venous congestion to occur more easily, leading to damage of the fragile wall of the angioma.     

Cerebellar mutism after removal of a vermian medulloblastoma in an adult

Cerebellar mutism is a rare postoperative phenomenon that generally occurs in children after resection of a cerebellar mass lesion. A 22-year-old man developed cerebellar mutism after posterior fossa surgery for a mass lesion in the vermis. Histological examination showed a medulloblastoma. The tumor was totally removed via a suboccipital approach. The patient developed mutism on the first postoperative day, which persisted for two weeks. Thereafter, this condition gradually improved. Although pathophysiology and the anatomical substrate of cerebellar mutism still remain unclear, it is important that neurosurgeons be aware of this syndrome after posterior fossa surgery in adults. This phenomenon usually has a self-limiting course and a favorable prognosis for resolution within the first three months.     

Cerebellar mutism caused by arteriovenous malformation of the vermis

Transient mutism following posterior fossa tumour resection in children is well known in the literature. To our Knowledge, this phenomenon has never been reported without surgical intervention. We report a case of cerebellar mutism secondary haemorrhage from a vermian arteriovenous malformation (AVM), which resolved to ataxic dysarthria after 6 weeks. Embolization of the AVM was performed and the patient's clinical status continued to improve gradually till she became normal 6 months from the insult. The mutism was due to rupture of the AVM which might correlate the cerebellar mutism with the transient vasospasm of the blood vessels supplying the cerebellum. It is possible for a spontaneus posterior fossa bleed to result in transient mutism similar to post surgical mutism.     

Migraine,a result of increased CSF pressure: A new pathophysiological concept (preliminary report)

Summary Clinical and neuroradiological evaluation of 40 adult patients, suffering from migraine-type headache, produced evidence of a relationship between migraine, increased CSF pressure in the posterior fossa and cerebellar herniation. These findings have led to an alternative pathophysiological concept of migraine. A disturbance of CSF circulation is thought to be the underlying factor, which causes increased pressure in the basal cisterns and posterior fossa. This results in headache, acquired cerebellar herniation and, in severe cases, spasm of the vertebral arteries with subsequent cerebral ischemia. There seems to be no essential difference in pathophysiology between common and classic migraine.     

Anomalous subarcuate loop. Technical note

An anomalous subarcuate loop of the anterior inferior cerebellar artery is described in which the artery is adherent to or penetrates the posterior fossa dura in the subarcuate fossa. When encountered during acoustic neurilemoma surgery, the artery should be carefully mobilized along with a sleeve of dura to prevent its injury.     

Computer-assisted stereotactic resection of posterior fossa lesions

A method for computer-assisted stereotactic laser resection of posterior fossa lesions is described. This procedure has been used successfully to treat 10 patients having a variety of lesions deep in the cerebellar hemisphere, vermis, and brainstem with satisfactory postoperative neurologic results.     

特发性脊柱侧凸患者小脑扁桃体位置与后颅窝容积关系的影像学观察

目的:比较特发性脊柱侧凸(idiopathic scoliosis,IS)患者与年龄匹配的非脊柱畸形患者后颅窝容积的差异,探讨IS患者后颅窝发育异常与小脑扁桃体生理性下疝的关系。方法:从2009年1月至2011年6月我科收治的500例IS患者中选取70例年龄16～20岁、Risser征5级、术前行站立位全脊柱正侧位X线片及颈枕部MRI检查的患者为研究对象(A组),男48例,女22例,侧凸平均Cobb角51.2°±14.1°。选取年龄匹配的58例非脊柱畸形患者作为对照组(B组),男27例,女31例。测量两组研究对象头颈正中矢状位MRI中小脑扁桃体下缘超出枕骨大孔连线(AB线)的距离(d值)、枕骨大孔前后径(AB)、斜坡长度(AD)、枕上长度(BC)以及后颅窝矢状径(CD),比较两组小脑扁桃体位置及后颅窝容积差异。根据MRI表现,将IS组患者分为伴生理性小脑扁桃体下疝组(A1组)和不伴生理性小脑扁桃体下疝组(A2组),分析后颅窝容积与小脑扁桃体生理性下疝间关系及主弯Cobb角与小脑扁桃体生理性下疝程度的相关性。结果:A组d值和枕骨大孔前后径明显大于B组(P<0.05),而AD、BC以及CD均明显小于B组(P<0.05)。A组患者d值与主弯Cobb角无显著相关性(P>0.05),其生理性小脑扁桃体下疝发生率为22.9%,A1组患者BC显著小于A2组患者(P<0.05),AB、AD、CD两组间均无显著性差异(P>0.05)。结论:IS患者小脑扁桃体位置低可能与其后颅窝枕骨大孔增大而斜坡、枕骨发育受限有关,IS患者成骨异常可能也影响到了其后颅窝发育。     

On the management of neonatal tentorial damage. Eight case reports and a review of the literature

Summary From the history of 15 personal patients—8 reported here in extenso — and from 63 patients in the literature with the diagnosis of posterior fossa subdural haemorrhage during life, we discuss the possibility of detecting tentorial damage on computed tomography (CT) and ultrasound (US) scan. The association of a (peri)cerebellar haemorrhage with peritentorial bleeding around the straight sinus and a subdural haemorrhage between both occipital cerebral lobes is suggestive of tentorial laceration(s). Both coronal CT scan and sagittal US scan are very helpful in locating these haemorrhages near the falco-tentorial junction. The conservative management of one of our infants with very extensive but asymmetric posterior fossa haemorrhage, leading to resorptive hydrocephalus, is compared with both surgical and conservative treatment of patients from the literature. Two reasons that warrant neurosurgical intervention are: life-threatening brain-stem compression—as in one of our own patients—and acute obstructive hydrocephalus. Craniotomy of the posterior fossa within the neonatal period does not prevent later-onset resorptive hydrocephalus. The communicating nature of this latter process is adequately demonstrated by lumbar isotope cisternography. Finally, neonatal posterior fossa subdural haemorrhage is one of the many causes of cyst-like structures behind the cerebellum.     

A case presenting with hydrocephalus and posterior fossa subdural effusion

We report a case of hydrocephalus due to posterior cranial fossa subdural effusion. The patient was a 4-year-old boy, presenting headache and nausea, with a medical history of viral meningitis 2 months before. Cerebrospinal fluid provided no evidence of infection, and symptoms caused by increased intracranial pressure gradually deteriorated, although glycerol infusion was effective temporarily. Computed tomography revealed marked ventriculomegaly with subdural effusion in the right posterior cranial fossa. The subarachnoid space in the posterior fossa was very tight, and the cerebellum and brain stem were compressed anteriorly. Magnetic resonance imaging demonstrated stenosis of the aqueduct and foramens of Luschka and Magendie. The cerebeller tonsil was dislocated inferiorly, indicating impending herniation, so an emergency operation was performed. Ventriculoperitoneal shunt was undertaken after implantation of an Ommaya reservoir for the posterior fossa subdural effusion. The patient's postoperative course was uneventful, and the symptoms were improved. Although hydrocephalus and subdural effusion following viral meningitis is rare, neuroimaging studies such as CT and MRI should be examined when a young child suffers from symptoms of increased intracranial pressure.     

Unusual case of depressed fracture of the posterior cranial fossa associated with the syndrome of acute central cervical spinal cord injury

Linear fractures through the occipital bone are common, whereas depressed fractures in the posterior cranial fossa are rare because the occipital bone is protected by the surrounding thick muscles. The authors describe an unusual case of depressed fracture localized in the posterior cranial fossa associated with the syndrome of acute central cervical spinal cord injury. A 50-year-old female struck her face against the table and fell backward, while drunk, resulting in the bruise over the occipital region. Three days after injury she was transferred to our hospital because of progressive disturbance of consciousness, brain stem dysfunction and tetraplegia. Neurological examination on admission showed that she was drowsy, had tetraplegia and could not speak. However, she could obey commands only by moving her eyes and the ocular movements were normal in all directions except for horizontal nystagmus. Plain skull x-ray revealed a conspicuously depressed fracture in the posterior cranial fossa, but cervical spine x-ray showed neither fracture nor dislocation. Immediately suboccipital craniectomy was done and there were a thin subdural hematoma on the cerebellar surface, cerebellar contusion, and subarachnoid hemorrhage around the cisterna magna. Soon after operation impaired consciousness and paraplegia were improved, but recovery of both arms was delayed. Five months after injury, she still had left IX, X and XI nerve paresis, bilateral arm weakness, dysarthria, swallowing disturbance and bilateral sensory disturbance below C4 level. These findings indicated that she had sustained brain stem and cerebellar compression by the depressed fracture and also had suffered an acute central cervical spinal cord injury.     

Complications of posterior cranial fossa surgery—an institutional experience of 500 patients

BackgroundThe complication of the posterior fossa surgery is seldom described in the literature. The purposes of this retrospective study are to draw attention to the potential complications associated with posterior fossa surgery and to critically review the predisposing factors that might influence the complication rate.MethodsWe undertook a 10-year (1992-2002) retrospective study of all posterior fossa surgery performed at LSUHSC. A total of 500 patients were obtained from the operation database, and they were categorized into 5 groups based on the surgical approaches: (1) cerebellopontine angle lesion, (2) microvascular decompression for facial pain and spasm, (3) cerebellar lesions, (4) Chiari I decompression, and (5) petroclival lesions. Data collected for analysis included patient demographics, pathological characteristics of the lesions, and the postoperative complications that occurred as unexpected and undesirable events that prolonged hospital stay and may require surgical/medical intervention.ResultsOf the 500 patients reviewed, 220 (44%) patients had tumor resections at the cerebellopontine angle; 110 (22%) patients had microvascular decompression for trigeminal neuralgia and hemifacial spasm; 86 (17.2%) patients had cerebellar lesions; 60 (12%) patients had Chiari I decompression; and 24 (4.8%) patients required transpetrosal approaches for petroclival lesions. The overall complication rate in our study was 31.8%, affecting 159 patients. Cerebrospinal fluid leaks were the most frequently encountered, presenting in 65 (13%) patients followed by meningitis in 46 (9.2%) patients, wound infection in 35 (7%) patients, and CN palsies in 24 (4.8%) patients. Other complications that were observed to develop almost exclusively in patients undergoing cerebellar parenchymal tumor resection included cerebellar edema in 25 (5%) patients, hydrocephalus in 23 (4.6%) patients, cerebellar hematoma in 15 (3%) patients, and cerebellar mutism in 6 (1.2%) patients. The overall mortality rate related to surgery was 2.6% occurring in 13 patients.ConclusionPosterior fossa surgery involves greater morbidity and mortality and has a wider variety of complications than surgery in the supratentorial compartment. These complications may be avoided by careful perioperative planning, strict adherence to aseptic technique, meticulous microsurgical dissection, proper wound closure, and the judicious use of prophylactic agent. A thorough understanding of the patient's history, neurological findings, imaging studies, operative anatomy, as well as all potential adverse events associated with the procedure is also essential to minimize complications.     

Pre-operative cerebellar mutism secondary to vagus nerve schwannoma

Cerebellar mutism, also known as 'posterior fossa syndrome,' is an uncommon condition often reported after posterior fossa tumour resection in the paediatric population. It is infrequently associated with other intrinsic cerebellar pathologies. We hereby report a rare case of pre-operative cerebellar mutism associated with an extrinsic posterior fossa lesion - vagus nerve schwannoma.     

An intracranial aneurysm on the feeding artery of a cerebellar hemangioblastoma. Case report.

A case of cerebellar hemangioblastoma with a coexistent arterial aneurysm on the feeding artery of the tumor is reported. The patient presented with an acute onset of headache, loss of consciousness, and left-sided hemiparesis due to a posterior fossa hemorrhage found adjacent to a hemangioblastoma. Four-vessel angiography revealed an aneurysm on the anterior inferior cerebellar artery (AICA), which was the main feeding vessel of the hemangioblastoma. Successful total excision of the hemangioblastoma and clipping of the AICA aneurysm achieved in a one-stage operation was demonstrated on postoperative angiography.     

Combined Retrolabyrinthine-Retrosigmoid Approach for Improved Exposure of the Posterior Fossa Without Cerebellar Retraction

The combined retrolabyrinthine-retrosigmoid (CRR) approach utilizes anterior retraction of the sigmoid sinus to improve exposure of the posterior fossa without cerebellar retraction. The CRR was initially used for vestibular neurectomy but is now utilized for acoustic neuroma excision with hearing preservation and exposure for clipping of basilar and vertebrobasilar aneurysms. This excellent exposure of the cerebellopontine angle without cerebellar retraction can be used for all posterior fossa exposures.