[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.

Cerebellar haemorrhage in the extremely preterm infant.

AIM: The aim of this study was to investigate the incidence, risk factors and developmental outcomes of cerebellar haemorrhage in the extremely preterm infant. METHODS: Over a 4-year period from January 2004, all patients with cerebellar haemorrhage born at 24-27 weeks gestation or with a birthweight < 1000 g were identified from database review. All patients had cranial ultrasound scans including views from the mastoid fontanelle. To verify the incidence, a review of all reports over the 4-year period and a review of all cranial imaging over a 2-year period were carried out. RESULTS: From the data analysed on 339 neonates, five cases of cerebellar haemorrhage were identified, four on ultrasound scan (1.2%) and one on magnetic resonance imaging (1.5% total). Two cases were associated with grade III peri-intraventricular haemorrhage. The cases had diverse maternal, antenatal and post-natal risk factors. The two with associated peri-intraventricular haemorrhage have developmental delay. The cases with isolated cerebellar haemorrhage had good neurodevelopmental outcomes. CONCLUSIONS: A low incidence of cerebellar haemorrhage identified from the mastoid fontanelle was demonstrated. The neurodevelopmental outcome was better than that described in previous reports.

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.

Intractable hiccups as a presenting symptom of Chiari I malformation.

INTRODUCTION: Hiccups as the only presenting symptom in neurosurgical practice is uncommon. CASE HISTORY: We report a case of a 22-year-old man who was evaluated for a 9-month history of intractable hiccups. He was diagnosed with a case of Chiari malformation type I. DISCUSSION: Surgical decompression improved the symptoms of the patient. The cause and pathogenesis of hiccups are discussed. CONCLUSION: Chiari malformation should be considered in patients with intractable hiccups, who are otherwise asymptomatic for any neurological problems.

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.

Presyrinx in children with Chiari malformations.

BACKGROUND: Presyrinx is a reversible state of spinal cord edema caused by alterations in CSF flow dynamics. Only three pediatric cases have been reported previously. We describe the clinical and radiologic features of presyrinx in six pediatric patients. METHODS: We electronically searched pediatric spine MRI reports generated at our institution from January 1995 to April 2007 for the keyword "presyrinx" and identified six patients with this radiologic diagnosis. We reviewed the neuroimaging studies and medical records for information regarding symptoms, treatment, and outcome. RESULTS: Of six patients identified with presyrinx, four had a Chiari I malformation and two had a Chiari II malformation. The MRI characteristics of the presyrinx included T2 prolongation, mild indistinct T1 prolongation, and cord enlargement without frank cavitation. Cine phase-contrast MRI studies were performed in three patients and showed severely diminished or absent CSF flow at the foramen magnum. Five patients underwent surgical decompression. All three patients with postoperative spine imaging showed restoration of CSF flow and resolution of the presyrinx. Symptoms of chronic or acute myelopathy attributable to the presyrinx were present in two patients. These symptoms resolved postoperatively. CONCLUSIONS: Chiari I and II malformations obstructing CSF flow at the craniocervical junction may cause presyrinx in children. Presyrinx should be considered in the differential diagnosis of chronic or acute myelopathy in patients at risk for abnormal CSF flow dynamics.

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.