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Dimitrios C. Nikas, Lorenzo Bello, Amir A. Zamani and Peter McL. Black

The authors reviewed 175 low-grade hemispheric gliomas surgically treated by one surgeon (P.B.) between 1987 and 1996: 74 astrocytomas (42%), 35 oligodendrogliomas (20%), 52 mixed gliomas (30%), 12 gangliogliomas (7%), and two ependymomas (1%). Patient age ranged from 7.5 to 81.9 years (mean 39.2 years); 84 patients (48%) were males and 91 (52%) females. Postsurgical follow-up review ranged from 0.1 to 225.2 months (mean 36.2 months, median 24.9 months). Either T2-weighted or contrast-enhanced T1-weighted magnetic resonance (MR) images were used to evaluate the percentage of resection achieved and volume of residual disease postoperatively. The majority of patients (55%) had seizures as the presenting symptom, and 45% experienced preoperative symptoms for more than 12 months. Tumor enhancement was present in 21% of cases. In 66% of surgical procedures at least one of the following technical adjuncts was used: monitored local anesthesia, real-time MR imaging, stereotactic guidance with computerized tomography, three dimensional reconstruction, cortical mapping with cortical stimulation, somatosensory or visual evoked potential recording, corticography, or intraoperative ultrasound. Intraoperative MR imaging was used for 40 (22.9%) of the craniotomies and nine (5.14%) biopsies. There were no surgery-related deaths. Complications appeared in 6% of the patients. Progression to a higher-grade tumor occurred in 9.2% of patients within the 3-year follow-up period.

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Marco Riva, Enrica Fava, Marcello Gallucci, Alessandro Comi, Alessandra Casarotti, Tommaso Alfiero, Fabio A. Raneri, Federico Pessina and Lorenzo Bello

OBJECT

Intraoperative language mapping is traditionally performed with low-frequency bipolar stimulation (LFBS). High-frequency train-of-five stimulation delivered by a monopolar probe (HFMS) is an alternative technique for motor mapping, with a lower reported seizure incidence. The application of HFMS in language mapping is still limited. Authors of this study assessed the efficacy and safety of HFMS for language mapping during awake surgery, exploring its clinical impact compared with that of LFBS.

METHODS

Fifty-nine patients underwent awake surgery with neuropsychological testing, and LFBS and HFMS were compared. Frequency, type, and site of evoked interference were recorded. Language was scored preoperatively and 1 week and 3 months after surgery. Extent of resection was calculated as well.

RESULTS

High-frequency monopolar stimulation induced a language disturbance when the repetition rate was set at 3 Hz. Interference with counting (p = 0.17) and naming (p = 0.228) did not vary between HFMS and LFBS. These results held true when preoperative tumor volume, lesion site, histology, and recurrent surgery were considered.

Intraoperative responses (1603) in all patients were compared. The error rate for both modalities differed from baseline values (p < 0.001) but not with one another (p = 0.06). Low-frequency bipolar stimulation sensitivity (0.458) and precision (0.665) were slightly higher than the HFMS counterparts (0.367 and 0.582, respectively). The error rate across the 3 types of language errors (articulatory, anomia, paraphasia) did not differ between the 2 stimulation methods (p = 0.279).

CONCLUSIONS

With proper setting adjustments, HFMS is a safe and effective technique for language mapping.

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Idiopathic pinealitis

Case report

Demetrios C. Nikas, Umberto De Girolami, Amir A. Zamani, Geraldine S. Pinkus, Lorenzo Bello, Matthias Kirsch and Peter McL. Black

✓ This 63-year-old man presented with complaints of “having a feeling of falling backward” over a 3-month period. Results of his general physical examination, laboratory studies, and neurological examination were unremarkable. A magnetic resonance image revealed a 1.8 × 1.4 × 1.2—cm enhancing mass in the posterior third ventricle just above the corpora quadrigemina. The pineal gland was found to be diffusely enlarged at operation and separable from the posterior thalamus and was totally resected. The patient had an uneventful postoperative course but continues to be somewhat confused. The lesion consisted of a remarkable chronic inflammatory cell infiltrate permeating the pineal lobules and was composed of T and B lymphocytes, macrophages, eosinophils, and mast cells. Immunoperoxidase studies did not demonstrate Langerhans cells, and a search for microorganisms was unrevealing. There was no evidence of neoplasia; results of immunostaining for germ cell markers and other tumor-associated antigens were negative.

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Marco Rossi, Marco Conti Nibali, Luca Viganò, Guglielmo Puglisi, Henrietta Howells, Lorenzo Gay, Tommaso Sciortino, Antonella Leonetti, Marco Riva, Luca Fornia, Gabriella Cerri and Lorenzo Bello

OBJECTIVE

Brain mapping techniques allow one to effectively approach tumors involving the primary motor cortex (M1). Tumor resectability and maintenance of patient integrity depend on the ability to successfully identify motor tracts during resection by choosing the most appropriate neurophysiological paradigm for motor mapping. Mapping with a high-frequency (HF) stimulation technique has emerged as the most efficient tool to identify motor tracts because of its versatility in different clinical settings. At present, few data are available on the use of HF for removal of tumors predominantly involving M1.

METHODS

The authors retrospectively analyzed a series of 102 patients with brain tumors within M1, by reviewing the use of HF as a guide. The neurophysiological protocols adopted during resections were described and correlated with patients’ clinical and tumor imaging features. Feasibility of mapping, extent of resection, and motor function assessment were used to evaluate the oncological and functional outcome to be correlated with the selected neurophysiological parameters used for guiding resection. The study aimed to define the most efficient protocol to guide resection for each clinical condition.

RESULTS

The data confirmed HF as an efficient tool for guiding resection of M1 tumors, affording 85.3% complete resection and only 2% permanent morbidity. HF was highly versatile, adapting the stimulation paradigm and the probe to the clinical context. Three approaches were used. The first was a “standard approach” (HF “train of 5,” using a monopolar probe) applied in 51 patients with no motor deficit and seizure control, harboring a well-defined tumor, showing contrast enhancement in most cases, and reaching the M1 surface. Complete resection was achieved in 72.5%, and 2% had permanent morbidity. The second approach was an “increased train approach,” that is, an increase in the number of pulses (7–9) and of pulse duration, using a monopolar probe. This second approach was applied in 8 patients with a long clinical history, previous treatment (surgery, radiation therapy, chemotherapy), motor deficit at admission, poor seizure control, and mostly high-grade gliomas or metastases. Complete resection was achieved in 87.5% using this approach, along with 0% permanent morbidity. The final approach was a “reduced train approach,” which was the combined use of train of 2 or train of 1 pulses associated with the standard approach, using a monopolar or bipolar probe. This approach was used in 43 patients with a long clinical history and poorly controlled seizures, harboring tumors with irregular borders without contrast enhancement (low or lower grade), possibly not reaching the cortical surface. Complete resection was attained in 88.4%, and permanent morbidity was found in 2.3%.

CONCLUSIONS

Resection of M1 tumors is feasible and safe. By adapting the stimulation paradigm and probe appropriately to the clinical context, the best resection and functional results can be achieved.

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Marco Rossi, Marco Conti Nibali, Luca Viganò, Guglielmo Puglisi, Henrietta Howells, Lorenzo Gay, Tommaso Sciortino, Antonella Leonetti, Marco Riva, Luca Fornia, Gabriella Cerri and Lorenzo Bello

OBJECTIVE

Brain mapping techniques allow one to effectively approach tumors involving the primary motor cortex (M1). Tumor resectability and maintenance of patient integrity depend on the ability to successfully identify motor tracts during resection by choosing the most appropriate neurophysiological paradigm for motor mapping. Mapping with a high-frequency (HF) stimulation technique has emerged as the most efficient tool to identify motor tracts because of its versatility in different clinical settings. At present, few data are available on the use of HF for removal of tumors predominantly involving M1.

METHODS

The authors retrospectively analyzed a series of 102 patients with brain tumors within M1, by reviewing the use of HF as a guide. The neurophysiological protocols adopted during resections were described and correlated with patients’ clinical and tumor imaging features. Feasibility of mapping, extent of resection, and motor function assessment were used to evaluate the oncological and functional outcome to be correlated with the selected neurophysiological parameters used for guiding resection. The study aimed to define the most efficient protocol to guide resection for each clinical condition.

RESULTS

The data confirmed HF as an efficient tool for guiding resection of M1 tumors, affording 85.3% complete resection and only 2% permanent morbidity. HF was highly versatile, adapting the stimulation paradigm and the probe to the clinical context. Three approaches were used. The first was a “standard approach” (HF “train of 5,” using a monopolar probe) applied in 51 patients with no motor deficit and seizure control, harboring a well-defined tumor, showing contrast enhancement in most cases, and reaching the M1 surface. Complete resection was achieved in 72.5%, and 2% had permanent morbidity. The second approach was an “increased train approach,” that is, an increase in the number of pulses (7–9) and of pulse duration, using a monopolar probe. This second approach was applied in 8 patients with a long clinical history, previous treatment (surgery, radiation therapy, chemotherapy), motor deficit at admission, poor seizure control, and mostly high-grade gliomas or metastases. Complete resection was achieved in 87.5% using this approach, along with 0% permanent morbidity. The final approach was a “reduced train approach,” which was the combined use of train of 2 or train of 1 pulses associated with the standard approach, using a monopolar or bipolar probe. This approach was used in 43 patients with a long clinical history and poorly controlled seizures, harboring tumors with irregular borders without contrast enhancement (low or lower grade), possibly not reaching the cortical surface. Complete resection was attained in 88.4%, and permanent morbidity was found in 2.3%.

CONCLUSIONS

Resection of M1 tumors is feasible and safe. By adapting the stimulation paradigm and probe appropriately to the clinical context, the best resection and functional results can be achieved.

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Marco Rossi, Federico Ambrogi, Lorenzo Gay, Marcello Gallucci, Marco Conti Nibali, Antonella Leonetti, Guglielmo Puglisi, Tommaso Sciortino, Henrietta Howells, Marco Riva, Federico Pessina, Pierina Navarria, Ciro Franzese, Matteo Simonelli, Roberta Rudà and Lorenzo Bello

OBJECTIVE

Surgery for low-grade gliomas (LGGs) aims to achieve maximal tumor removal and maintenance of patients’ functional integrity. Because extent of resection is one of the factors affecting the natural history of LGGs, surgery could be extended further than total resection toward a supratotal resection, beyond tumor borders detectable on FLAIR imaging. Supratotal resection is highly debated, mainly due to a lack of evidence of its feasibility and safety. The authors explored the intraoperative feasibility of supratotal resection and its short- and long-term impact on functional integrity in a large cohort of patients. The role of some putative factors in the achievement of supratotal resection was also studied.

METHODS

Four hundred forty-nine patients with a presumptive radiological diagnosis of LGG consecutively admitted to the neurosurgical oncology service at the University of Milan over a 5-year period were enrolled. In all patients, a policy was adopted to perform surgery according to functional boundaries, aimed at achieving a supratotal resection whenever possible, without any patient or tumor a priori selection. Feasibility, general safety, and tumor or patient putative factors possibly affecting the achievement of a supratotal resection were analyzed. Postsurgical patient functional performance was evaluated in five cognitive domains (memory, language, praxis, executive functions, and fluid intelligence) using a detailed neuropsychological evaluation and quality of life (QOL) examination.

RESULTS

Total resection was feasible in 40.8% of patients, and supratotal resection in 32.3%. The achievement of a supratotal versus total resection was independent of age, sex, education, tumor volume, deep extension, location, handedness, appearance of tumor border, vicinity to eloquent sites, surgical mapping time, or surgical tools applied. Supratotal resection was associated with a long clinical history and histological grade II, suggesting that reshaping of brain networks occurred. Although a consistent amount of apparently MRI-normal brain was removed with this approach, the procedure was safe and did not carry additional risk to the patient, as demonstrated by detailed neuropsychological evaluation and QOL examination. This approach also improved seizure control.

CONCLUSIONS

Supratotal resection is feasible and safe in routine clinical practice. These results show that a long clinical history may be the main factor associated with its achievement.

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Andrea Szelényi, Lorenzo Bello, Hugues Duffau, Enrica Fava, Guenther C. Feigl, Miroslav Galanda, Georg Neuloh, Francesco Signorelli and Francesco Sala

There is increasing evidence that the extent of tumor removal in low-grade glioma surgery is related to patient survival time. Thus, the goal of resecting the largest amount of tumor possible without leading to permanent neurological sequelae is a challenge for the neurosurgeon. Electrical stimulation of the brain to detect cortical and axonal areas involved in motor, language, and cognitive function and located within the tumor or along its boundaries has become an essential tool in combination with awake craniotomy. Based on a literature review, discussions within the European Low-Grade Glioma Group, and illustrative clinical experience, the authors of this paper provide an overview for neurosurgeons, neurophysiologists, linguists, and anesthesiologists as well as those new to the field about the stimulation techniques currently being used for mapping sensorimotor, language, and cognitive function in awake surgery for low-grade glioma. The paper is intended to help the understanding of these techniques and facilitate a comparison of results between users.

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Marco Rossi, Luca Fornia, Guglielmo Puglisi, Antonella Leonetti, Gianmarco Zuccon, Enrica Fava, Daniela Milani, Alessandra Casarotti, Marco Riva, Federico Pessina, Gabriella Cerri and Lorenzo Bello

OBJECTIVE

Apraxia is a cognitive-motor deficit affecting the execution of skilled movements, termed praxis gestures, in the absence of primary sensory or motor disorders. In patients affected by stroke, apraxia is associated with lesions of the lateral parietofrontal stream, connecting the posterior parietal areas with the ventrolateral premotor area and subserving sensory-motor integration for the hand movements. In the neurosurgical literature to date, there are few reports regarding the incidence of apraxia after glioma surgery. A retrospective analysis of patients who harbored a glioma around the central sulcus and close to the parietofrontal circuits in depth showed a high incidence of long-term postoperative hand apraxia, impairing the patients’ quality of life. To avoid the occurrence of postoperative apraxia, the authors sought to develop an innovative intraoperative hand manipulation task (HMt) that can be used in association with the brain mapping technique to identify and preserve the cortical and subcortical structures belonging to the praxis network.

METHODS

The intraoperative efficacy of the HMt was investigated by comparing the incidence of postoperative ideomotor apraxia between patients undergoing mapping with (n = 79) and without (n = 41) the HMt. Patient groups were balanced for all demographic and clinical features.

RESULTS

In patients with lesions in the dominant hemisphere, the HMt dramatically reduced the incidence of apraxia, with a higher sensitivity for the ideomotor than for the constructional abilities; patients with lesions in the nondominant hemisphere benefitted from the HMt for both ideomotor and constructional abilities. The administration of the test did not reduce the extent of resection.

CONCLUSIONS

The HMt is a safe and feasible intraoperative tool that allowed surgeons to prevent the occurrence of long-term hand apraxia while attaining resection goals for the surgical treatment of glioma.

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Guglielmo Puglisi, Tommaso Sciortino, Marco Rossi, Antonella Leonetti, Luca Fornia, Marco Conti Nibali, Alessandra Casarotti, Federico Pessina, Marco Riva, Gabriella Cerri and Lorenzo Bello

OBJECTIVE

The goal of surgery for gliomas is maximal tumor removal while preserving the patient’s full functional integrity. At present during frontal tumor removal, this goal is mostly achieved, although the risk of impairing the executive functions (EFs), and thus the quality of life, remains significant. The authors investigated the accuracy of an intraoperative version of the Stroop task (iST), adapted for intraoperative mapping, to detect EF-related brain sites by evaluating the impact of the iST brain mapping on preserving functional integrity following a maximal tumor resection.

METHODS

Forty-five patients with nondominant frontal gliomas underwent awake surgery; brain mapping was used to establish the functional boundaries for the resection. In 18 patients language, praxis, and motor functions, but not EFs (control group), were mapped intraoperatively at the cortical-subcortical level. In 27 patients, in addition to language, praxis, and motor functions, EFs were mapped with the iST at the cortical-subcortical level (Stroop group). In both groups the EF performance was evaluated preoperatively, at 7 days and 3 months after surgery.

RESULTS

The iST was successfully administered in all patients. Consistent interferences, such as color-word inversion/latency, were obtained by stimulating precise white matter sites below the inferior and middle frontal gyri, anterior to the insula and over the putamen, and these were used to establish the posterior functional limit of the resection. Procedures implemented with iST dramatically reduced the EF deficits at 3 months. The EOR was similar in Stroop and control groups.

CONCLUSIONS

Brain mapping with the iST allows identification and preservation of the frontal lobe structures involved in inhibition of automatic responses, reducing the incidence of postoperative EF deficits and enhancing the further posterior and inferior margin of tumor resection.