Albino Bricolo

Motor evoked potential monitoring improves outcome after surgery for intramedullary spinal cord tumors: a historical control study

OBJECTIVE:The value of intraoperative neurophysiological monitoring (INM) during intramedullary spinal cord tumor surgery remains debated. This historical control study tests the hypothesis that INM monitoring improves neurological outcome. METHODS:In 50 patients operated on after September 2000, we monitored somatosensory evoked potentials and transcranially elicited epidural (D-wave) and muscle motor evoked potentials (INM group). The historical control group consisted of 50 patients selected from among 301 patients who underwent intramedullary spinal cord tumor surgery, previously operated on by the same team without INM. Matching by preoperative neurological status (McCormick scale), histological findings, tumor location, and extent of removal were blind to outcome. A more than 50% somatosensory evoked potential amplitude decrement influenced only myelotomy. Muscle motor evoked potential disappearance modified surgery, but more than 50% D-wave amplitude decrement was the major indication to stop surgery. The postoperative to preoperative McCormick grade variation at discharge and at a follow-up of at least 3 months was compared between the two groups (Students t tests). RESULTS:Follow-up McCormick grade variation in the INM group (mean, +0.28) was significantly better (P = 0.0016) than that of the historical control group (mean, –0.16). At discharge, there was a trend (P = 0.1224) toward better McCormick grade variation in the INM group (mean, –0.26) than in the historical control group (mean, –0.5). CONCLUSION:The applied motor evoked potential methods seem to improve long-term motor outcome significantly. Early motor outcome is similar because of transient motor deficits in the INM group, which can be predicted at the end of surgery by the neurophysiological profile of patients.Received, February 23, 2005. Accepted, January 24, 2006. OBJECTIVE: The value of intraoperative neurophysiological monitoring (INM) during intramedullary spinal cord tumor surgery remains debated. This historical control study tests the hypothesis that INM monitoring improves neurological outcome. METHODS: In 50 patients operated on after September 2000, we monitored somatosensory evoked potentials and transcranially elicited epidural (D-wave) and muscle motor evoked potentials (INM group). The historical control group consisted of 50 patients selected from among 301 patients who underwent intramedullary spinal cord tumor surgery, previously operated on by the same team without INM. Matching by preoperative neurological status (McCormick scale), histological findings, tumor location, and extent of removal were blind to outcome. A more than 50% somatosensory evoked potential amplitude decrement influenced only myelotomy. Muscle motor evoked potential disappearance modified surgery, but more than 50% D-wave amplitude decrement was the major indication to stop surgery. The postoperative to preoperative McCormick grade variation at discharge and at a follow-up of at least 3 months was compared between the two groups (Student’s t tests). RESULTS: Follow-up McCormick grade variation in the INM group (mean, 0.28) was significantly better (P 0.0016) than that of the historical control group (mean, –0.16). At discharge, there was a trend (P 0.1224) toward better McCormick grade variation in the INM group (mean, –0.26) than in the historical control group (mean, –0.5). CONCLUSION: The applied motor evoked potential methods seem to improve longterm motor outcome significantly. Early motor outcome is similar because of transient motor deficits in the INM group, which can be predicted at the end of surgery by the neurophysiological profile of patients.

Microsurgical removal of petroclival meningiomas: a report of 33 patients

This is a report of 33 consecutive cases of petroclival meningioma treated surgically at our institution over the last 10 years; there were 21 women and 12 men between the ages of 27 and 68 (mean age, 52). All patients were assessed by computed tomographic scans including coronal sections and bone algorithm studies; in most cases, digital subtraction angiography and magnetic resonance imaging were also done. The largest tumor diameter was between 2 and 3.5 cm in 14 cases, 3.5 to 6 cm in 15 cases, and over 6 cm in 4 cases. Dural attachment predominantly involved the clivus and apical petrous bone on one side only; in 14 cases, however, the tumor grew over the clivus midline or crossed the tentorial notch. Cranial nerve deficit was extant in all cases and was commensurate with tumor size. Cerebellar signs and somatic motor deficits were present in 60 and 30% of cases, respectively. The surgical approaches used were the retromastoid-retrosigmoid in 23 cases, subtemporal in 5 cases, and combined retromastoid subtemporal presigmoid in the remaining 5. Total removal was achieved in 26 cases (79%); incomplete removal occurred in 7 cases (21%). The extent of tumor removal and operative morbidity were not significantly related to tumor size. Brain stem indentation, arterial and cranial nerve encasement, and epidural invasion were the main factors that prevented total tumor removal and influenced operative morbidity. There was no intraoperative mortality, but three patients (9%) died perioperatively. In the postoperative period, most patients went through momentary neurological deterioration, chiefly due to new cranial nerve deficits. The average follow-up was 4.3 years in 27 patients; of these 17 were unchanged and 10 were improved. Before surgery, only 13 patients were self-sufficient; at long-term follow-up, another 6 had achieved independence. Our experience suggests that, even though real petroclival meningiomas still represent a formidable surgical challenge, such tumors can in most cases be removed completely with low attendant mortality and acceptable morbidity.

Extradural hematoma: toward zero mortality. A prospective study.

This is a prospective analysis of 107 consecutive cases of extradural hematoma treated during the last 3 years at the Department of Neurosurgery of the University Hospital of Verona (Italy). The overall mortality was 5%; 89% of the patients made a good recovery or had only moderate residual disability. We regard this as meaningful progress compared to recent reports from other sources showing mortality rates of approximately 20%. The majority of our patients (57%) underwent operation within 6 hours of injury; 60% went into surgery with a Glasgow coma scale (GCS) score between 8 and 15. No deaths occurred among patients reaching surgery with a GCS score of 8 or better; all patients with scores of 8 to 15 made a good recovery (63 cases). Seventeen patients went into surgery while still free of neurological signs, and 8 had only one dilated pupil; all 25 made good recoveries. A flexion posture at admission cuts the chances of a good outcome by one-half; an extension posture cuts the chances to one-fourth. Ninety-five per cent of the patients had fractures of the skull; only 21% had the classical lucid interval. The cause of all 5 deaths was identified as stemming from avoidable errors in management in outlying hospitals (2 cases) or in our own department (3 cases). The results of this study indicate that zero mortality from extradural hematoma is a realistic goal for a modern, well-run care system for head-injured patients that includes prompt referral by community doctors and suitable hospital facilities for constant access to emergency neurosurgery.

Radiosurgical Treatment of Cavernous Sinus Meningiomas: Experience with 122 Treated Patients

OBJECTIVE To evaluate the efficacy of gamma knife (GK) radiosurgery, in terms of neurological improvement and tumor growth control (TGC), for a large series of patients with cavernous sinus meningiomas. METHODS Between February 1993 and January 2002, 156 patients with cavernous sinus meningiomas (35 male and 121 female patients; mean age, 56.1 yr) were treated with GK radiosurgery in our department. GK radiosurgery was used as a first-choice treatment for 75 of 156 patients and as postoperative adjuvant therapy for 81 of 156 patients (all with Grade I meningiomas). Eligibility criteria for radiosurgery were as follows: symptomatic meningiomas and/or documented tumor progression on magnetic resonance imaging scans, conditions of high operative risk, patient refusal of microsurgery or reoperation, tumor volume of <20 cm3, and location no less than 2 mm from the optic pathways. RESULTS Follow-up data for at least 12 months were available for 122 patients (median follow-up period, 48.9 mo). Clinical conditions were improved or stable for 118 of 122 patients (97%). Neurological recovery was observed for 78.5% of patients treated with GK radiosurgery alone and for 60.5% of patients treated with adjuvant therapy (P < 0.05). Adequate TGC was documented for 119 of 122 tumors (97.5%), with shrinkage/disappearance in 75 of 122 cases (61.5%) and no variation in volume in 44 of 122 cases (36%); the overall actuarial progression-free survival rate at 5 years was 96.5%. Tumor size regression was observed for 80% of patients with follow-up periods of more than 30 months, compared with 43.5% of patients with follow-up periods of less than 30 months (P < 0.0002). Radiosurgical sequelae were transient in 4 of 122 cases (3.0%) and permanent in 1 case (1%). CONCLUSION For the follow-up periods in our series (median, >4 yr), GK radiosurgery seems to be both safe (permanent morbidity rate, 1%) and effective (97% neurological improvement/stability, 97.5% overall TGC, and 96.5% actuarial TGC at 5 yr). GK radiosurgery might be considered a first-choice treatment for selected patients with cavernous sinus meningiomas.

Microsurgical Removal of Petroclival MeningiomasA Report of 33 Patients Clinical Study

: This is a report of 33 consecutive cases of petroclival meningioma treated surgically at our institution over the last 10 years; there were 21 women and 12 men between the ages of 27 and 68 (mean age, 52). All patients were assessed by computed tomographic scans including coronal sections and bone algorithm studies; in most cases, digital subtraction angiography and magnetic resonance imaging were also done. The largest tumor diameter was between 2 and 3.5 cm in 14 cases, 3.5 to 6 cm in 15 cases, and over 6 cm in 4 cases. Dural attachment predominantly involved the clivus and apical petrous bone on one side only; in 14 cases, however, the tumor grew over the clivus midline or crossed the tentorial notch. Cranial nerve deficit was extant in all cases and was commensurate with tumor size. Cerebellar signs and somatic motor deficits were present in 60 and 30% of cases, respectively. The surgical approaches used were the retromastoid-retrosigmoid in 23 cases, subtemporal in 5 cases, and combined retromastoid subtemporal presigmoid in the remaining 5. Total removal was achieved in 26 cases (79%); incomplete removal occurred in 7 cases (21%). The extent of tumor removal and operative morbidity were not significantly related to tumor size. Brain stem indentation, arterial and cranial nerve encasement, and epidural invasion were the main factors that prevented total tumor removal and influenced operative morbidity. There was no intraoperative mortality, but three patients (9%) died perioperatively. In the postoperative period, most patients went through momentary neurological deterioration, chiefly due to new cranial nerve deficits. The average follow-up was 4.3 years in 27 patients; of these 17 were unchanged and 10 were improved. Before surgery, only 13 patients were self-sufficient; at long-term follow-up, another 6 had achieved independence. Our experience suggests that, even though real petroclival meningiomas still represent a formidable surgical challenge, such tumors can in most cases be removed completely with low attendant mortality and acceptable morbidity.

Prognostic factors in low-grade supratentorial astrocytomas: A uni-multivariate statistical analysis in 76 surgically treated adult patients

A retrospective uni-multivariate statistical analysis was performed on 32 prognostic factors to investigate their importance in predicting survival in a series of 76 adult patients with low-grade supratentorial astrocytomas treated over a 13-year period. The end point used for this study was the length of survival. The median survival time was 40 months. Overall actuarial survival at 2, 5, and 10 years was 69%, 38%, and 22%, respectively. Radical resection of the neoformation, a higher preoperative Karnofsky performance status (KPS) score, and an age younger than 50 years are strongly correlated with survival; postoperative radiotherapy appears to be associated with increased survival only in patients under 50 years of age.

Surgery for intramedullary spinal cord tumors: the role of intraoperative (neurophysiological) monitoring

In spite of advancements in neuro-imaging and microsurgical techniques, surgery for intramedullary spinal cord tumors (ISCT) remains a challenging task. The rationale for using intraoperative neurophysiological monitoring (IOM) is in keeping with the goal of maximizing tumor resection and minimizing neurological morbidity. For many years, before the advent of motor evoked potentials (MEPs), only somatosensory evoked potentials (SEPs) were monitored. However, SEPs are not aimed to reflect the functional integrity of motor pathways and, nowadays, the combined used of SEPs and MEPs in ISCT surgery is almost mandatory because of the possibility to selectively injury either the somatosensory or the motor pathways. This paper is aimed to review our perspective in the field of IOM during ISCT surgery and to discuss it in the light of other intraoperative neurophysiologic strategies that have recently appeared in the literature with regards to ISCT surgery. Besides standard cortical SEP monitoring after peripheral stimulation, both muscle (mMEPs) and epidural MEPs (D-wave) are monitored after transcranial electrical stimulation (TES). Given the dorsal approach to the spinal cord, SEPs must be monitored continuously during the incision of the dorsal midline. When the surgeon starts to work on the cleavage plane between tumor and spinal cord, attention must be paid to MEPs. During tumor removal, we alternatively monitor D-wave and mMEPs, sustaining the stimulation during the most critical steps of the procedure. D-waves, obtained through a single pulse TES technique, allow a semi-quantitative assessment of the functional integrity of the cortico-spinal tracts and represent the strongest predictor of motor outcome. Whenever evoked potentials deteriorate, temporarily stop surgery, warm saline irrigation and improved blood perfusion have proved useful for promoting recovery, Most of intraoperative neurophysiological derangements are reversible and therefore IOM is able to prevent more than merely predict neurological injury. In our opinion combining mMEPs and D-wave monitoring, when available, is the gold standard for ISCT surgery because it supports a more aggressive surgery in the attempt to achieve a complete tumor removal. If quantitative (threshold or waveform dependent) mMEPs criteria only are used to stop surgery, this likely impacts unfavorably on the rate of tumor removal.

The role of Gamma Knife Radiosurgery in the management of cavernous sinus meningiomas

PURPOSE To evaluate the efficacy of Gamma Knife (GK) radiosurgery in terms of neurologic improvement and tumor growth control (TGC) in a large series of patients with cavernous sinus meningioma (CSM). METHODS AND MATERIALS One hundred thirty-eight patients with CSM (28 males, 110 females; mean age: 56.2 years) were treated with GK between February 1993 and February 2001. GK was used as a first-choice treatment in 68/138 patients and as postoperative adjuvant therapy in 70/138. In 32 patients, it was possible to compare the size of the planned treatment volume to tumor volume using the conformity index (CI); optimal CI values were taken to be < or =1.5 (range: 0.94-2.24). RESULTS A follow-up (FU) period of at least 12 months was available for 111 patients (median: 48.2 months, range: 12.1-84.5 months). Clinical conditions were improved or stable in 107/111 patients (96.5%). Neurologic recovery was observed in 76% of cases treated by GK alone and in 56.5% of adjuvant treatments (p < 0.03). Adequate TGC was documented in 108/111 tumors (97%), with shrinkage/disappearance in 70/111 (63%) and no variation in volume in 38/111 (34%); the overall actuarial progression-free survival rate at 5 years was 96%. Tumor size regression was observed in 79.5% of patients with FU >30 months, compared with 47.5% of patients with FU <30 months (p < 0.001). One hundred percent TGC was shown in treated patients with a CI < or =1.5 (20/32), compared with 92% TGC in cases with a CI >1.5 (p < 0.15, NS). Radiosurgical sequelae were transient in 4/111 cases (3.5%) and permanent in one case (1%). CONCLUSIONS For the FU period of our series (median: >4 years), GK radiosurgery seems to be both safe (permanent morbidity 1%) and effective (96% neurologic improvement/stability, 97% overall TGC, 96% actuarial TGC at 5 years) and might be considered as a first-choice treatment for selected patients with CSM.

Assessment and surgical management of posterior fossa epidermoid tumors: report of 28 cases.

OBJECTIVE The management of a series of 28 patients operated on for posterior fossa epidermoids is reviewed, emphasizing the need for long-term follow-up. We discuss the rationale for a comprehensive classification system that may allow the comparison of results from homogeneous series. METHODS We grouped the tumors to differentiate the surgical management according to various tumor sites and the degree of extension. Twenty patients harbored tumors located in the cerebellopontine angle, five patients harbored tumors in the fourth ventricle, and three patients harbored tumors in the posterior fossa basal. In 17 patients, extensions of tumors outside the posterior fossa included the following regions: the suprasellar/ chiasmatic (n = 5), the parasellar/temporobasal (n = 5), and the mesencephalic/pineal (n = 7). Tumor extension was also defined by the number of regions involved. Pre- and postoperative magnetic resonance imaging and computed tomographic findings collected in 17 and 28 patients, respectively, were carefully evaluated. RESULTS Clinical features and surgical approaches varied according to location and growth pattern. Fifty-seven percent of the tumors were completely removed. A higher total removal rate was achieved in patients with tumors confined to the primary location. One patient (3%) died in the perioperative period. Approximately half of the patients presented with transient mild focal deficit impairments resulting from the manipulation of the nervous structure over a wide area. There was a higher rate of surgical complications with fourth ventricle and mesencephalic extended cerebellopontine angle tumors. The mean follow-up period was 8.6 years. Thirty percent of the patients with subtotal removal experienced symptomatic recurrences after 8.1 years, whereas all patients with total removal were still asymptomatic. The recurrence-free survival rate was 95% at 13 years for patients with total removal compared with 65% for patients with subtotal removal. Problems of identification of tumor regrowth are discussed. CONCLUSION By assessing posterior fossa epidermoids, we determined that location and extension play a major role in the prognosis. Our data suggest that more aggressive surgery is called for at first operation, and that a second operation should be planned when regrowth becomes symptomatic and/or tends to extend outside its original site.

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.