Surgical treatment of spinal dural arterio-venous fistulae: long-term results and analysis of prognostic factors.

BACKGROUND: Spinal dural arterio-venous fistulae (SDAVF) are slow-flow extramedullary vascular lesions which account for 75-80% of all spinal vascular malformations. At present there is no agreed view with regard to the best therapeutic option being surgical or endovascular, and several reports favour one or other form of management. This is so because of lack of consistent literature, as well as knowledge, concerning the long-term clinical outcome of the patients. The objective of this study is to retrospectively analyse the results obtained with patients operated for a SDAVF at the Department of Neurosurgery of Verona during a 15-year period and to evaluate possible prognostic factors related to neurological outcome. PATIENTS AND METHODS: Between January 1987 and May 2002, 29 patients with SDAVF were operated at the Department of Neurosurgery of Verona. For 25 of these patients we were able to obtain a clinical follow-up using telephone interviews. The patients were evaluated with the Aminoff and Logue's scale and subsequently stratified into three classes of disability. An overall score (gait and micturition, G + M) of 0-3 indicates a mild disability, a score between 4 and 5 indicates a moderate disability and a score between 6 and 8 a severe disability. All patients underwent surgical treatment which was mainly the first therapeutic option. Following surgery, the patients were re-evaluated with the same neurological scale. We also investigated with statistical analysis the possible impact on clinical outcome of the major clinical, neuroradiological and surgical variables. RESULTS: The epidemiological, clinical, radiological and pathological features of our group of patients are very similar to those previously described in the literature. For 10 patients surgery consisted simply of the interruption of the intradural arterialized draining vein (with or without closure of the small extradural arterial afferents), whereas in the remaining 15 patients coagulation or excision of the fistulous dura was also accomplished. At the last follow-up (mean 7.3 years; in 19 patients longer than 5 years), 10 patients had improved (40%), 11 were stable (44%) and 4 had deteriorated (16%). We determined that only the pre-operative neurological status, described by the G value in the Aminoff and Logue's scale and the class of disability, had an impact on clinical outcome. CONCLUSIONS: This retrospective study confirms that the surgical treatment results of SDAVF are satisfactory even if evaluated after many years. Given these results, and in accordance with the majority of the literature, we concur that surgery should be the first choice treatment for these spinal vascular lesions in order to avoid a dangerous delay and consequently further neurological deterioration. In our group of patients the only prognostic factor statistically related to clinical outcome was the pre-treatment neurological status, particularly the grade of paraparesis and the class of disability.

Monitoring of motor pathways during brain stem surgery: what we have achieved and what we still miss?

Intraoperative neurophysiological monitoring (IOM) has established itself as one of the paths by which modern neurosurgery can improve surgical results while minimizing morbidity. IOM consists of both monitoring (continuous "on-line" assessment of the functional integrity of neural pathways) and mapping (functional identification and preservation of anatomically ambiguous nervous tissue) techniques. In posterior-fossa and brainstem surgery, mapping techniques can be used to identify - and therefore preserve - cranial nerves, their motor nuclei and corticospinal or corticobulbar pathways. Similarly, free-running electromyography (EMG) and muscle motor-evoked potential (mMEP) monitoring can continuously assess the functional integrity of these pathways during surgery. Mapping of the corticospinal tract, at the level of the cerebral peduncle as well as mapping of the VII, IX-X and XII cranial nerve motor nuclei on the floor of the fourth ventricle, is of great value to identify "safe entry-zones" into the brainstem. Mapping techniques allow recognizing anatomical landmarks such as the facial colliculus, the hypoglosseal and glossopharyngeal triangles on the floor of the fourth ventricle, even when normal anatomy is distorted by a tumor. On the basis of neurophysiological mapping, specific patterns of motor cranial nuclei displacement can be recognized. However, brainstem mapping cannot detect injury to the supranuclear tracts originating in the motor cortex and ending on the cranial nerve motor nuclei. Therefore, monitoring techniques should be used. Standard techniques for continuously assessing the functional integrity of motor cranial nerves traditionally rely on the evaluation of spontaneous free-running EMG in muscles innervated by motor cranial nerves. Although several criteria have been proposed to identify those EMG activity patterns that are suspicious for nerve injury, the terminology remains somewhat confusing and convincing data regarding a clinical correlation between EMG activity and clinical outcome are still lacking. Transcranial mMEPs are also currently used during posterior-fossa surgery and principles of MEP monitoring to assess the functional integrity of motor pathways are similar to those used in brain and spinal-cord surgery. Recently, current concepts in muscle MEP monitoring have been extended to the monitoring of motor cranial nerves. So-called "corticobulbar mMEPs" can be used to monitor the functional integrity of corticobulbar tracts from the cortex through the cranial motor nuclei and to the muscle innervated by cranial nerves. Methodology for this purpose has appeared in the literature only recently and mostly with regards to the VII cranial nerve monitoring. Nevertheless, this technique has not yet been standardized and some limitations still exist. In particular, with regards to the preservation of the swallowing and coughing reflexes, available intraoperative techniques are insufficient to provide reliable prognostic data since only the efferent arc of the reflex can be tested.

Haemorrhagic stroke and vasculitic-like cerebral angiography in a patient with eosinophilic fasciitis. Case report.

Cerebral vasculitis is an uncommon cause of haemorrhagic stroke. A case of intracerebral haemorrhage in a patient with eosinophilic fasciitis, a rare scleroderma-like connective tissue disease, with a possible inflammatory involvement of cerebral vessels is reported. Pathogenetic mechanism of such association and diagnostic controversies are reviewed.

Multimodality stereotactic approach to the treatment of cystic craniopharyngiomas.

OBJECTIVES: To present the therapeutic reliability of a multimodality stereotactic approach (MSA) to cystic craniopharyngiomas (CPs), combining neuroendoscopy, intracavitary bleomycin and gamma knife (GK) radiosurgery. METHODS: 8 patients with mono- or multicystic CP (7/8 regrowths/recurrence) underwent stereotactic neuroendoscopy and subsequently treatment with intracavitary bleomycin and GK. They were clinically characterized by hypopituitarism (7 cases), visual impairment (7), endocranial hypertension (7), cognitive and behavioral disturbances (3), and cranial nerve deficits or focal signs (3). Concomitant hydrocephalus was observed in 3/8 patients. According to Backlund's classification, the treated CPs were classified as type A (3 cases), type Cc (4 cases) and type Dc (1 case). In all 8 patients, neuroendoscopy allowed evacuation of the cyst and, in multi-cystic CPs, fenestration of the interposed septa so as to create a single communicating cavity. Thus, a single catheter and Ommaya reservoir system was sufficient both for subsequent aspirations and for bleomycin injection (doses of 1.5-3 mg, usually repeated every 7-8 days, with total doses ranging from 3-35 mg). GK radiosurgery was carried out at a later stage on the collapsed cyst in type A forms, while in types Cc and Dc, it was used on the solid nodule on the same day as the neuroendoscopy. RESULTS: The median follow-up period was 42.5 months. Neurological improvement was observed in 8/8 patients. A complete response (reduction of the entire tumor volume > 90 %) was observed in 3/8 cases (type A), a subtotal response (reduction > 50 %) in 4/8 cases (types Cc and Dc), and a partial response (reduction < 50 %) in 1/8 cases (type Cc). Treatment of CP alone led to normalization of the ventricular morphology in the 3 patients with associated hydrocephalus. Transient GK-related visual worsening was recorded in one case only. One patient died because of ventriculitis after repeated shunt replacements. CONCLUSIONS: This MSA seems to be an effective and safe treatment alternative to microsurgery, above all in patients with regrowing/recurrent cystic CPs.

Extracellular levels of amino acids and choline in human high grade gliomas: an intraoperative microdialysis study.

The concentrations of endogenous amino acids and choline in the extracellular fluid of human cerebral gliomas have been measured, for the first time, by in vivo microdialysis. Glioblastoma growth was associated with increased concentrations of choline, GABA, isoleucine, leucine, lysine, phenylalanine, taurine, tyrosine, and valine. There was no difference between grade III and grade IV tumors in the concentrations of phenylalanine, isoleucine, tyrosine, valine, and lysine, whereas the concentrations of choline, aspartate, taurine, GABA, leucine, and glutamate were significantly different in the two tumor-grade subgroups. In contrast to the other compounds, the concentration of glutamate was decreased in glioma. The parenchyma adjacent to the tumor showed significant changes only in the extracellular concentration of glutamate, isoleucine, and valine. The concentrations of choline and the amino acids, glutamate, leucine, taurine, and tyrosine showed significant positive correlations with the degree of cell proliferation. Epilepsy, which is relatively common in subjects with gliomas, was shown to be a significant confounding variable when the extracellular concentrations of aspartate, glutamate and GABA were considered.

Motor evoked potential monitoring for spinal cord and brain stem surgery.

Intraoperative Neurophysiology (ION) has established itself as one of the means by which modern neurosurgery can improve surgical results while minimizing morbidity. The advent of motor evoked potential (MEP) monitoring represents a landmark in this recent progress. ION consists of monitoring (the continuous "on-line" assessment of the functional integrity of neural pathways) and mapping (the functional identification and preservation of anatomically ambiguous nervous tissue) techniques. In this chapter we have attempted to critically review the evolution of MEP use during monitoring and mapping techniques for neurosurgical procedures in the brainstem and the spinal cord, providing the neurophysiological theoretical background and practical aspects of clinical applications. According to the experience from our and other groups involved in ION, we suggest the following: 1) ION is mandatory whenever neurological complications are expected as predicted by a known pathophysiological mechanism. It is therefore advisable to perform ION when dealing with brain stem and intramedullary spinal cord lesions. 2) MEP monitoring after transcranial electrical stimulation is today a feasible and reliable technique for use under general anesthesia. MEP monitoring is the most appropriate technique to assess the functional integrity of descending motor pathways in the brainstem and, foremost, in the spinal cord. 3) Mapping of the corticospinal tract at the level of the cerebral peduncle as well as mapping of the VII, IX-X and XII cranial nerve motor nuclei on the floor of the fourth ventricle is of great value with which to identify "safe entry zones" into the brainstem. 4) Other techniques, although safe and feasible, still lack rigorous validation in terms of prognostic value and correlation with the postoperative neurological outcome. These techniques include mapping of the corticospinal tract within the spinal cord and monitoring of the corticobulbar tracts. These techniques, however, are expected to open new perspectives in the near future.

Surgical management of ruptured aneurysms in the eighth and ninth decades.

BACKGROUND: The surgical management of elderly patients with aneurysmal subarachnoid haemorrhage (SAH) is controversial. The present study was performed to more clearly define issues facing elderly SAH patients undergoing surgical repair of their aneurysms. METHOD: Between 1990 and 2000, 100 patients, aged 70 years or older, were managed consecutively with aneurysmal surgical repair at Verona City Hospital. Ninety-seven of these were analysed with regard to age, clinical grade on admission, radiological features, and specific management components (3 patients were excluded from further analysis because of inadequate follow up data). Surviving patients were followed up for a minimum of 6 months and clinical outcome was assessed. FINDINGS: Hydrocephalus requiring permanent CSF diversion occurred in 44% of cases surviving beyond 10 days from their SAH. The development of hydrocephalus requiring shunting was delayed more than 6 weeks in 7% of these cases. Medical complications occurred in 22% of cases. Clinical grade of haemorrhage (p<0.001), early hydrocephalus requiring ventriculostomy (p=0.003) and the development of medical complications (p=0.03) were significantly associated with poor outcome. Clinical vasospasm was not a major determinant of outcome in this group. The need for permanent CSF diversion was significantly associated with increasing age (p=0.03), intraventricular haemorrhage (p<0.001), early hydrocephalus requiring ventriculostomy (p=0.003) and the development of medical complications (p=0.05). INTERPRETATION: Elderly patients experience a different range of complications following aneurysmal subarachnoid haemorrhage than their younger counterparts. Clinicians should remain alert to the development of hydrocephalus, especially of delayed onset.

Gamma knife radiosurgery in the management of arteriovenous malformations of the Basal Ganglia region of the brain.

OBJECTIVES: The authors report the results of gamma knife (GK) radiosurgery on a clinical series of selected patients with basal ganglia arteriovenous malformations (BGAVMs) in the brain. Clinical, epidemiological, anatomical and functional characteristics of BGAVMs and of supratentorial cortical AVMs are comparatively analyzed, and their influence on radiosurgical outcome is discussed. METHODS: At our Department, 33 BGAVMs (21 with FU > 2 years) and 209 cortical AVMs (110 with FU > 2 years) with a radiosurgical volume

The microsurgical anatomy of the cisternal segment of the trochlear nerve, as seen through different neurosurgical operative windows.

OBJECTIVE: To describe the anatomy of the cisternal segment of the trochlear nerve as seen through different neurosurgical approaches. METHODS: The cisternal course of ten trochlear nerves was observed in five cadaveric embalmed heads, through the view afforded by the median infratentorial-supracerebellar, the extreme-lateral infratentorial-supracerebellar, and the combined presigmoid-subtemporal transtentorial approaches. The relationships of the trochlear nerve with the surrounding neuro-vascular structures were analyzed. RESULTS: We identified 3 segments of the cisternal trochlear nerve: quadrigeminal, ambient and tentorial. The median infratentorial-supracerebellar approach allowed exposure of the quadrigeminal segment, including the origin of the nerve. The extreme-lateral supracerebellar and the combined presigmoid-subtemporal transtentorial approaches provided visualization of the ambient and tentorial segments of the nerve. The tentorial segment runs in a dural canal contained in the free edge of the tentorium, surrounded by its own arachnoidal sleeve. CONCLUSION: The trochlear nerve is a very delicate structure that can be easily injured during approaches to the tentorial incisura. Accurate knowledge of its anatomy as seen through different operative windows is helpful in maintaining its integrity during surgery.

Gamma knife radiosurgery in meningiomas of the posterior fossa. Experience with 62 treated lesions.

OBJECTIVES: This study was undertaken to assess the role of the gamma knife (GK) in the treatment of meningiomas of the posterior cranial fossa (PCF) and to statistically analyze the predictability of arbitrarily-selected prognostic factors in such treatment. METHODS: From February 1993 to November 1998, 57 patients underwent GK treatment for 62 meningiomas of the PCF (19 M/38 F; average age, 57.5 years, ranging from 25 - 82 years). Tumor sites included: foramen jugular-petrous bone (26/62), petroclival (23/62), cerebellar convexity (6/62), tentorium (6/62), and foramen magnum (1/62). Single lesions were treated in 44/62 cases while meningiomatosis was treated in the remaining 18. Post-operative residual or recurrent tumor was found in 27/62 patients and, in 7/27, histology documented characteristics of biological aggressiveness (GII/III). Indications for radiosurgery included: advanced age, high operative risk, tumor volume < 20 ml, inoperable or refused for additional surgery. The prognostic factors statistically analyzed included: meningiomatosis (yes/no), radiosurgery as primary or adjuvant treatment, GI vs. GII/III histology, and tumor volume (< or = 5 ml vs. > 5 ml). RESULTS: The observation periods varied from 6 to 64.3 months (median 28.7 months). At the end of the study, 53/57 patients were alive and reported to be in stable or improved neurological condition. The cause of death for the remaining 4 patients included: 2 deaths associated with tumor progression, while 2 died due to causes unrelated to the disease. Neuroradiological evaluation documented the disappearance or reduction of the meningioma mass in 34/62 (55 %) cases, a stable imaging picture in 25/62 (40 %), and a progression only in 3/62 (5 %). To date, there have been no reported cases of post-GK permanent morbidity or mortality. Side effects observed were of a transient nature due to post-radiosurgical edema (6.5 %). With regard to statistical analysis, the only factor to appear to significantly influence efficacy of radiosurgery for tumor growth control (TGC) was the biological nature of the meningioma (chi(2) = 2.708). The presence of meningiomatosis, SR as a primary or adjuvant treatment nor tumor volume were shown to statistically influence tumor behavior after GK. CONCLUSIONS: The excellent results obtained for TGC with minimal associated side effects suggest that GK is an effective therapeutic tool also for treatment of PCF meningiomas.

Persistent hiccup as presenting symptom in medulla oblongata cavernoma: a case report and review of the literature.

A rare case of persistent intractable hiccup as presenting symptom of cavernous angioma in the medulla oblongata is reported. Pathophysiologic hypotheses about the triggering mechanism of hiccup are discussed, with special reference to the causes affecting the central nervous system. A review of the literature concerning medullary lesions presenting with persistent hiccup is also reported. Finally we have included some brief considerations about cavernous angiomas and the patterns of their clinical presentation, focusing on those located in the medulla oblongata.

Post-operative monitoring of cortical taurine in patients with subarachnoid hemorrhage: a microdialysis study.

Intracerebral MD enables the retrieval of endogenous substances from the extracellular fluid (ECF) of the brain and has been demonstrated to be a sensitive technique for early detection of subtle vasospasm-induced neurometabolic abnormalities in patients with subarachnoid hemorrhage (SAH). The aim of this study was to monitor cortical extracellular concentrations of energy metabolism markers, such as glucose and lactate, neurotransmitter amino acids, such as glutamate, aspartate, GABA and taurine to identify any neurochemical patterns of cerebral ischemia. A prospective clinical study was conducted on a group of 16 patients with non-severe SAH operated on within 72 hours after initial bleeding. Following aneurysm clipping, an MD catheter was inserted in the cortical region where vasospasm could be expected to develop, and perfused with artificial CSF at 0.3 microl/min flow rate. Dialysate was collected every 6 hours and then analyzed on High Performance Liquid Cromatography (HPLC) for glucose, lactate, pyruvate, glutamate, aspartate, GABA and taurine. Mean ECF taurine concentrations ranged from 1.4 + 0.7 to 12.3 + 7.8 micromol/l in single patients: global mean value was 5.8 + 3.8 micromol/l. In this series, the highest absolute taurine value was 25.7 micromol/l, observed in a patient who developed clinical and radiological signs of cerebral ischemia. Nine patients presented clinical disturbances related to cerebral vasospasm. In this setting, representing a mild-to-moderate hypoxic condition, MD data demonstrated that lactate is the most sensitive marker of cellular energy imbalance. Increased lactate levels positively correlated with glutamate (P<0.0001), aspartate (P<0.0001), GABA (P<0.0001) and taurine (P<0.0001) concentrations. These results suggest that also in humans increased taurine levels reflect a condition of cellular stress. This study confirms that MD is a sensitive technique to reveal subtle metabolic abnormalities possibly resulting in cell damage.

Cerebrospinal fluid flow dynamics study in Chiari I malformation: implications for syrinx formation.

Cerebrospinal fluid (CSF) flow abnormalities are known to be present in Chiari I malformation and to underlie the origin and progression of associated syringomyelia. The incidence of syrinx formation, however, is variable for unknown reasons. The aim of this study was to investigate whether differences in CSF flow dynamics in patients with Chiari I malformation may account for the different clinical and radiological presentation. Presurgical and postsurgical phase-contrast magnetic resonance imaging investigations were prospectively conducted in 47 adult patients with symptomatic Chiari I malformation. Patients were divided into two groups according to the presence (32 cases) or absence (15 cases) of syrinx. Cerebrospinal fluid flow patterns were evaluated at four regions of interest: prebulbar cistern, foramen magnum, and the ventral and dorsal spinal subarachnoid spaces at the C-5 level. A temporal analysis of CSF flow waveforms was performed with measurement of cranial- and caudal-directed flow durations. All patients underwent a craniocervical decompressive procedure. Preoperatively, a prolonged caudal- directed (systolic) flow pattern was observed in patients with syringomyelia, as compared with normal control values obtained in 15 healthy volunteers. Conversely, a decreased systolic duration was observed in Chiari I patients who had malformation without syrinx. These trends were not statistically significant because of the considerable degree of overlap with the control values recorded in both groups. Additional comparison of the observed preoperative values obtained in patients with and those without syringomyelia indicated that the difference in systolic flow duration was significant at the ventral spinal subarachnoid space level (p = 0.003) and remarkable at the other levels, although not reaching statistical significance. Cerebrospinal fluid flow was minimal or absent at the foramen magnum (dorsal aspect) due to tonsillar herniation, precluding reliable quantitative measurement at this level. There was no evidence of communication between the fourth ventricle and syrinx in any case. Postoperatively, unobstructed CSF flow was recorded across the enlarged foramen magnum and into the artificial cisterna magna in all patients. A gradual restoration of near-normal flow patterns was observed in both groups. Inside the syrinx, fluid motion gradually tapered, no longer being detectable in 12 patients (37.5%) 1 year postsurgery. In patients with Chiari I malformation and associated syringomyelia different CSF flow patterns were demonstrated as compared with patients in whom syrinx was absent. Analysis of this study's findings supports the hypothesis that in Chiari I malformation an elongated systolic flow may prolong the condition of increased spinal subarachnoid pressure caused by the junctional obstruction, thus favoring CSF penetration into the spinal cord. It may be also proposed that a shortened systolic flow may be insufficient to maintain a hypertensive condition for enough time to induce syrinx formation.

Brain tumors in children under 3 years of age. Recent experience (1987-1997) in 39 patients.

Brain tumors in children under 3 years of age differ in clinical presentation and pathological behavior from those in older patients. In this study, we reviewed data from 39 children (24 males and 15 females) under 3 years of age who were treated for intracranial brain tumors since the introduction of magnetic resonance imaging. The purpose was to assess correlations between clinicoradiological and treatment-related factors, and their impact on prognosis. The following factors were analyzed: sex, age, duration of symptoms, intracranial hypertension on admission, tumor location, surgical removal and histology. Associations between these factors and correlations with prognosis were determined using bivariate analyses (chi(2) test) and Kaplan-Meier survival curves. Collins' concept of a period of risk recurrence was tested. Mean follow-up was 41 months (range 0-136). In March 1998, 20 children were still alive (51.2%) with a mean survival time of 65 months (range 2-136). The incidence of supratentorial tumors was significantly higher in children less than 1 year old (p = 0.027). Lateral tumors were 9/10 (90%) supratentorial versus only 7/26 (27%) midline tumors (p = 0.001). Outcome (dead or alive) was significantly better (p = 0.037) for low-grade astrocytomas (9/12 = 75% survival) when compared to ependymomas (2/6 = 33%) and primitive neuroectodermal tumors (3/12 = 25%). Total tumor removal was achieved in 20 cases and was associated with a better outcome (65 vs. 33% survival; p = 0.049). Survival analysis confirmed a worse prognosis for children with ependymomas and primitive neuroectodermal tumors (p = 0.011) and revealed a worse survival for children with intracranial hypertension on admission (p = 0.047). Total tumor removal was associated with a longer survival, although not significantly (p = 0. 077). Finally, we found no exceptions to Collins' law.

The pterional approach for the microsurgical removal of olfactory groove meningiomas.

OBJECTIVE: Currently, the surgical approach to olfactory meningiomas can vary depending on the size and expansion of the tumor, although surgical treatment still relies on the anterior bilateral craniotomy. Since 1989, we have use the pterional approach as a standard procedure in the treatment of 37 consecutive cases. We present our results in an attempt to contribute an alternative and valid surgical strategy for the treatment of these tumors. METHODS: Between 1989 and 1996, a series of 37 consecutive patients underwent microsurgical tumor resection using the unilateral pterional approach; all patients except one underwent operations on the right side. In 23 patients (62%), the tumor diameter measured approximately 6 cm, and the size was less than 4 cm in only 5 patients. The clinical presentation included mental dysfunction in 27 patients and visual impairment in 16 patients. The advantages of this approach are the early recognition of the posterior cerebrovascular complex, followed by a safe, rapid, and complete devascularization of the tumor and later by a favorable dissection of the capsular area from the frontal vascular branches and parenchyma. RESULTS: Total removal was achieved in all cases. There was one death unrelated to surgery. All patients presenting with mental dysfunction or with preoperative visual deficits recovered or improved. Postoperative magnetic resonance imaging confirmed complete tumor removal and demonstrated the brain parenchyma to be preserved and intact, primarily on the side opposite from the craniotomy. CONCLUSION: Our experience with the pterional approach suggests a greater role for this procedure in the treatment of olfactory groove meningiomas.

Arnold-Chiari malformation with syringomyelia in an elderly woman.

PRESENTATION: A 76-year-old woman, complaining of leg pain and unsteady gait for 3 years, presented with a spastic paraparetic gait, severe spasticity and touch, thermal and pain sensory loss limited to arms, lower thorax and upper abdomen. Brain and spinal cord magnetic resonance imaging showed a large loculated syrinx. Cerebellar tonsillar herniation into the foramen magnum was also seen (Arnold-Chiari malformation, type I). OUTCOME: The patient had successful cervico-spinal surgical decompression which resulted in marked reduction in hypertonia and weakness, normal gait and normal joint movement at 6 months. CONCLUSION: This unusual, late clinical presentation of a congenital disease underlines the importance of a comprehensive diagnostic work-up in the elderly patients with complex neurological signs.