[VEGETATIVE REACTIONS AS PROGNOSTIC FACTOR IN POSTERIOR FOSSA SURGERY].

Mortality rate related to posterior fossa tumors resection varies from 1 to 8 percent, according to various authors. It depends on tumor size and its growth characteristics. To determine the physiological acceptability of surgery, physiological significance of vegetative reactions associated with tumors resection has to be assessed. We divide these reactions (centrogenic reactions - CR) into 2 main groups. The first group has a relatively precise morphofunctional structure, similar to the classic reflex arc. They appear due to irritation of local centers or cranial nerves nuclei with mixed motor-vegetative structure. In most cases they are not connected with anatomic damage of CNS structures. The second group of CR is correlated with dysfunction of brain and represents brain s attempt to turn into a new functional state. Their presence should be considered as a functional degradation symptom, which might be even irreversible. Emergence from anesthesia in the operative room is not recommended in this clinical situation. Neurovegetative stabilization should be provided for a period of 6 to 24 hours after tumor resection.

Postoperative posterior fossa syndrome: unraveling the etiology and underlying pathophysiology by using magnetic resonance imaging.

BACKGROUND: Posterior fossa syndrome (PFS) is a severe, postoperative complication occurring in about 25 % of pediatric patients undergoing surgery for midline tumors in the posterior fossa. In recent years, MRI-based research elucidated the cause of PFS and shed new light on its putative pathophysiology. This review highlights the major advances arising from research of this topic. RESULTS: Postsurgical damage patterns in patients after posterior fossa surgery show that PFS results from bilateral surgical damage to the proximal efferent cerebellar pathways (pECPs). Surgical pECP disruption has other MRI-detectable effects that are more remote. Patients with PFS tend to develop global supratentorial cortical hypoperfusion, likely representing reversed, cerebello-cerebral diaschisis. Because this hypoperfusion is most prominent in frontal regions, cerebellar mutism may indicate a dominantly frontal lobe dysfunction, hence a peculiar form of speech apraxia. Injury to the pECP also leads to contralateral inferior olivary nucleus degeneration. When bilateral hypertrophic olivary degeneration (HOD) is observed after posterior fossa surgery, affected patients have clinical PFS. Therefore, it is suggested that bilateral HOD may be a sensitive and, in appropriate clinical settings, reliable a posteriori surrogate imaging indicator of bilateral disruption of the pECPs and consequently of PFS. Having such a "validation tool" presents new opportunities to develop better definitions for the phenotypes within the clinical spectrum of PFS. CONCLUSIONS: Anatomical and functional MRI techniques are suitable and valuable tools with which to detect structural changes and pathophysiological processes in the development and evolution of PFS and may be key, integral components of future clinical research endeavors.

Odontoid process and clival regeneration with Chiari malformation worsening after transoral decompression: an unexpected and previously unreported cause of "accordion phenomenon".

PURPOSE: Transoral odontoidectomy followed by occipito-cervical fixation is a widely used approach to relieve ventral compressions at the craniovertebral junction (CVJ). Despite the large amount of literature on this approach and its complications, no previous reports of odontoid process and clival regeneration following transoral odontoidectomy are present in the English literature. METHODS: We report the case of odontoid process and clival regeneration following transoral odontoidectomy. RESULTS: A 7-year-old boy presented with symptoms of brainstem and upper cervical spinal cord compression due to a complex malformation at the CVJ including a basilar invagination with Chiari malformation. A successful transoral microsurgical endoscopic-assisted odontoidectomy extended to the clivus was performed along with occipito cervical instrumentation and fusion. Clinical and radiological resolution of the CVJ compression was evident up to 2 years post-op, when the child had a relapse of some of the presenting symptoms and the follow-up CT and MRI scans showed a quite complete regrowth of the odontoid process, clival partial regeneration and recurrence of preoperative Chiari malformation. CONCLUSIONS: Besides the need of an accurate complete resection of the periosteum, which apparently was incompletely performed in our case, our experience suggests the need of resection of the odontoid down to the dentocentral synchondrosis and an accurate lateral removal of the bone surrounding the anterior tubercle of the Clivus is advised when an anterior CVJ decompression is required in children presenting a still evident synchondrosis at neuroradiological investigation.

Eye twist and tongue twist: a rare neurological syndrome.

A 27-year-old man presented with diplopia without features of raised intracranial pressure. He had left sixth cranial nerve (CN) palsy. Initial investigations in the form of blood tests, cerebrospinal fluid (CSF) opening pressure including CSF analysis and CT head were normal. He represented with paraparesis after 3 weeks. Examination revealed sixth CN palsy (eye twist) and new left-sided twelfth CN palsy (tongue twist), and hence Godtfredsen syndrome was diagnosed. MRI showed vertebral and clivus metastases. He showed partial response to high dose steroid. The statement 'sixth CN palsy may be a false localising sign' in neurology, should be followed by '....it can also be a true initial sign of clivus mass.'

Interdural haemorrhage of the posterior fossa due to infraclinoidal carotid artery aneurysm rupture.

Several anatomical studies indicate that the intracranial pachimeninges consist of two dural layers joined together, which divide while bordering the venous sinuses, therefore located in an interdural space. We present here an uncommon case of haematoma due to rupture of an infraclinoidal internal carotid artery aneurysm. The dome of the aneurysm leaned against the posterior wall of the cavernous sinus and, following laceration, pierced the inner dural layer and caused its detachment from the periosteal layer, thus determining a truly interdural haematoma which progressively involved the whole posterior fossa. A 42-year-old female was admitted to our institution with a recent history of thunderclap headache and right ophthalmoparesis. Two cerebral computerised scan tomographies performed elsewhere tested negative for subarachnoid haemorrhage. A cerebral magnetic resonance imaging (MRI) showed a thin collection of blood adjacent to the clivus and all along the wall of the posterior fossa and foramen magnum. A right infraclinoid internal carotid artery aneurysm was also diagnosed, subsequently better highlighted on angiography. The patient underwent surgery with aneurysm clipping. Post-operative course was uneventful, and control angiography showed complete exclusion of the aneurysm from blood circulation. The patient was discharged 5 days later. At 3 months follow-up ophthalmoplegia had disappeared, and the patient had fully recovered. The possibility of a truly interdural location, particularly in cases of non-traumatic parasellar or clival haematomas, must be included in the differential diagnosis of posterior fossa extra-axial haemorrhages. MRI is the test of choice for diagnostic purposes.

Multiple cranial neuropathy as the initial presentation of metastatic prostate adenocarcinoma: case report and review of literature.

The skull base is an atypical metastatic site for prostate carcinoma. It is usually encountered late in the disease process in patients with known advanced disease. However, skull base involvement causing cranial nerve palsies may rarely be the presenting sign of prostate carcinoma. Such patients may present to a number of specialties including neurosurgery and can pose a diagnostic challenge in the absence of lower urinary tract symptoms. Here, we describe an unusual case of prostate adenocarcinoma presenting as a central skull base tumour with multiple cranial neuropathy.

An unusual cause of posterior fossa mass: Lhermitte-Duclos disease.

Lhermitte-Duclos disease (LDD) (dysplastic cerebellar gangliocytoma) is a rare disorder of unknown pathogenesis, presenting with signs and symptoms resulting from obstruction of cerebrospinal fluid flow and mass effect in the posterior fossa. Magnetic resonance imaging is the diagnostic modality of choice allowing preoperative diagnosis with characteristic findings. Surgery is the choice of treatment. The typical histopathological findings of LDD are characterized by widening of the molecular layer, absence of the Purkinje cell layer and hypertrophy in the granule cell layer. Herein we report an adolescent girl with LDD diagnosed preoperatively by the conventional and advanced MR techniques.

Symptomatic prepontine cistern flattening after an arachnoid cyst shunting: a report of 2 cases.

BACKGROUND: Controversy still exists about the best management modality for congenital arachnoid cyst. Shunting procedures have been one of the treatment options offered to patients with this condition. Although arachnoid cysts shunting have been associated with a variety of clinical conditions, its relationship with flattened prepontine cistern has not been described. CASE DESCRIPTION: We describe two children with congenital arachnoid cyst managed with cystoperitoneal shunt, both of whom were later discovered to have developed flattened prepontine cistern and imaging findings of overcrowding of the posterior cranial fossa. CONCLUSION: These cases demonstrate that flattening of the prepontine cisterns and acquired posterior cranial fossa overcrowding may be a potential fall out in patients with cystoperitoneal shunt due to an arachnoid cyst.

Developmental outcome of children with enlargement of the cisterna magna identified in utero.

An enlarged cisterna magna can be identified during routine ultrasound screening in the second half of pregnancy. It is important to be able to give an accurate prognosis. We evaluated the developmental outcome of these children. A total of 29 fetuses with a large cisterna magna identified in utero were compared to 35 children with a normal fetal ultrasound. The children were evaluated by the Gesell Developmental Schedules and the Peabody Developmental Motor Scale. The study group showed a significantly worse performance in the Gesell test. However, the overall performance for both groups was within normal limits. Four children in the study group had a borderline developmental quotient. Both groups performed similarly in the Peabody test. Walking age was significantly delayed in the study group. Children with an enlarged cisterna magna may be at risk for mild developmental delay. In cases of nonisolated enlargement of the cisterna magna, the outcome may be guarded.

Spinal cord lipoma without dysraphism in the infancy that extends intracranially. Case report and review of the literature.

BACKGROUND: Spinal intramedullary lipoma extending to the posterior fossa is very rare in children. We made a revision of the literature and report the diverse opinions and surgical procedures. CASE DESCRIPTION: We report the case of a 16-month-old male infant who was operated on in the Pediatric Neurosurgical Unit of our hospital; his clinical and surgical outcome are related. CONCLUSION: Intramedullary lipoma of the spinal cord with intracranial extension in infancy is a very rare pathology reported in the literature. Our patient was treated with decompression and subtotal removal; he had a critical postoperative course but was recovering slowly after that. Most authors prefer incomplete resection because these lesions do not have a clear-cut margin. Another neurosurgeon performed a decompression only, without resection. Some authors performed the surgical treatment before symptom progression. Another surgeon reported that the surgical indication is debatable when the neurologic manifestations are poor or absent. The surgical indication and the strategy for treatment are controversial and they depend on the clinical situations of the patients.

A case with prepontine (clival) arachnoid cyst manifested as trigeminal neuralgia.

Most cases of "idiopathic" trigeminal neuralgia are thought to originate from vascular compression of the trigeminal root entry zone. In this case, we describe a young man presenting with the symptoms of trigeminal neuralgia associated with a prepontine (clival) arachnoid cyst.

Hindbrain herniation: A review of embryological theories.

Herniation of the hindbrain outside of the setting of intracranial hypertension, trauma, and brain tumors is an uncommon phenomenon with estimated incidence of less than 1%. In the late 1890's, Hans Chiari, a German pathologist, classified hindbrain herniation into three forms. This classification was then extended to include six types. We reviewed the current literature for the proposed embryological theories as well as the potential genetic mutations/syndromes associated with the hindbrain herniation or Chiari malformation. The review is illustrated by a unique cadaver with Chiari type I malformation (i.e. herniation of the cerebellar tonsils through the foramen magnum). Finally, it seems that no single theory could explain all forms of the Chiari malformation, and that this malformation might be a heterogeneous entity.

Primary spontaneous CSF rhinorrhea through the clivus: possible etiopathology.

Primary spontaneous cerebrospinal fluid (CSF) rhinorrhea is rare. Only two such cases with a defect in the clivus have been previously reported in the world literature. The purpose of this report is not to discuss the operative approach or results but the etiopathogenesis of the defect at this very rare site. One patient had a defect in the posterior wall of the sphenoid sinus, just caudal to the dorsum sellae. In the other, a psuedomeningocele (thickened arachnoid outpouching) was found protruding into the sphenoid sinus through a defect in the middle of the clivus. Both cases were successfully managed with transsphenoidal surgery. Two additional cases of primary spontaneous CSF rhinorrhea through a defect in clivus are reported. The possible mechanism of the fistulae are discussed.

Radiologically atypical congenital posterior fossa dermoid cyst presenting late in life.

We report the case of a 74-year-old woman who presented with deterioration in gait, short-term memory loss and urinary incontinence. She had a past history of excision of a cervical dermal sinus tract at the age of 5 years. CT scan in 2004 revealed ventriculomegaly and an extremely hypodense ovoid structure lying in the midline low posterior fossa with calcification anteriorly. On MRI, the lesion was hypointense on T1-eighted and hyperintense on T2-weighted images, with incomplete suppression on fluid-attenuated inversion-recovery images and marked restriction on diffusion weighted images. Cerebrospinal fluid isotope study revealed non-communicating hydrocephalus. Posterior fossa crainectomy and removal of the lesion was undertaken. Pathological study revealed a dermoid cyst. Post-operatively, her hydrocephalus persisted and a ventriculo-atrial shunt was inserted with excellent functional recovery.

Empty sella syndrome associated with a hyperfunctioning microadenoma invading the clivus.

The empty sella syndrome is usually associated with normal pituitary function. If dysfunction is present, this is commonly hypofunction. Hyperfunctioning microadenomas have been described in the presence of the empty sella syndrome. We present the first reported cases of a microadenoma invading the clivus associated with an empty sella.

Tentorial dural arteriovenous fistulas.

BACKGROUND: Tentorial dural arteriovenous fistula is uncommon but is a life-threatening lesion. We present our experience with 5 patients with TDAVFs, review the relevant literature, and present the rationale of our current management strategy. METHOD: The data of 5 patients with TDAVFs treated in Huashan Hospital, Shanghai, China, between June 2002 and May 2003 were reviewed retrospectively, including their illness history, neuroimaging, operation records, and follow-up data. RESULTS: There were 3 females and 2 males with ages from 25 to 52 years (average, 38 years). Clinical manifestations were acute SAH in 2 patients and progressive neurologic deficits in 3 patients. Magnetic resonance imaging and DSA were major diagnostic and follow-up modalities. All cases belonged to Borden classification type 3. A tentorial marginal type was present in 3 cases, a tentorial lateral type in 1 case, and a tentorial medial type in 1 case. Preoperative transarterial embolization was done in 3 patients. All patients underwent craniotomy with the coagulation of the fistulas and surrounding tentorial dura mater, and the disconnection of leptomeningeal venous drainage. The surgical approaches were via transanterior petrous approach in 3 cases, subtemporal intradural approach in 1 case, and unilateral occipital and transtentorial approach in 1 case. All patients had clinical improvement. There was no surgical mortality and morbidity. Postoperative DSA confirmed obliteration of TDAVFs in 3 cases; MRI demonstrated the thrombosis of venous aneurysm and disappearance of previous brainstem edema in 1 case, and partial thrombosis of venous aneurysm in another case. Follow-up study ranging from 2 to 3 years (average, 2.5 years) showed no recurrence, and all patients have resumed their normal activities. CONCLUSIONS: Tentorial dural arteriovenous fistulas are aggressive vascular lesions causing SAH and progressive neurologic deficits. Prompt diagnosis and definite treatment are mandatory. Obliteration of the fistulas and/or leptomeningeal venous drainage should be the goal of treatment. Microsurgical procedures with/without endovascular intervention are the best choice of treatment.

Middle and posterior fossa aspergilloma.

BACKGROUND: Aspergilloma of the brain is a rare disease. Among its varied presentations, a solitary intracranial mass is very uncommon. A preoperative diagnosis of it is very difficult, but a perioperative squash smear/frozen section can identify the pathology. Because of its rarity in immunocompetent patients and the difficulty in preoperative diagnosis, we have illustrated this case and its presentation and management. METHODS: A 27-year-old man presented with an h/o right-sided weakness along with headache and ear discharge. A computed tomographic (CT) scan showed a large irregular, space-occupying lesion in the middle and posterior cranial fossa. He had a mastoidectomy done 3 years before for chronic suppurative otitis media. After a symptom-free interval of 1 year, he was investigated for severe earache on the same side. A CT scan at that time showed a space occupying mass in the right temporal bone and right inferior temporal lobe. A biopsy and histopathology of the lesion revealed a chronic granulomatous mass. He was started on antituberculous drugs and was on it for 7 months at the time of presentation. RESULTS: He underwent a suboccipital craniectomy and total excision of the mass. Postoperatively, his consciousness improved but began to deteriorate on the third postoperative day. A repeat CT scan showed hydrocephalus and total removal of the mass. An external ventricular drain was put and he was ventilated, but he died on the fourth postoperative day. Histopathology report came as aspergilloma. CONCLUSION: This report highlights the rare presentation of aspergilloma in an immunocompetent patient. It emphasizes the importance of suspecting this disease in such patients and the role of intraoperative squash smear preparations or frozen section in the diagnosis as routine diagnostic procedures that will help in early pharmacotherapeutic interventions in adjunct to surgery.

Spontaneous relapsing and recurring large multiloculated posterior fossa enteric cyst.

Intracranial enterogenous cyst is an uncommon entity. We report a case of enterogenous cyst of the posterior fossa situated posterolateral to the brain stem and extending into the left CP angle cistern. Patient had spontaneous regression and recurrence of the cyst. Clinical features and radiological findings are described. Near total excision of the cyst was carried out through the retro mastoid route. Patient made a good postoperative recovery.