Microsurgical anatomy and approaches to thalamic gliomas. Part 2: Maximal safe resection of thalamic gliomas improves outcomes. A single-center experience.

OBJECTIVE: As presented in Part 1 of this series, thalamic gliomas (TGs) are deep-seated, difficult-to-access tumors surrounded by vital neurovascular structures. Given their high operative morbidity, TGs have historically been considered inoperable lesions. Although maximal safe resection (MSR) has become the treatment standard for lobar and even deep-seated mediobasal temporal and insular gliomas, the eloquent location of TGs has precluded this management strategy, with biopsy and adjuvant treatment being the mainstay. The authors hypothesized that MSR can be achieved with low morbidity and mortality for TGs, thus resulting in improved outcomes. METHODS: A retrospective single-center study was performed on all TG patients from 2006 to 2020. Clinical, imaging, and pathology reports were obtained. Univariate and multivariate analyses were performed to determine prognostic variables. Case examples illustrate various approaches and the rationale for staging resections of more complex TGs. RESULTS: A total of 42 patients (26 males, 16 females), among them 12 pediatric (29%) cases, were included. Their mean age was 36.0 ± 21.4 (median 30, range 3-73) years. The median maximal tumor diameter was 45 (range 19-70) mm. Eighteen patients (43%) had a prior stereotactic needle tumor biopsy, with the ultimate diagnosis changed for 7 patients (39%) following microsurgical resection. The most common surgical approaches were transtemporal (29%), anterior interhemispheric transcallosal (29%), and superior parietal lobule (25%). Overall, the combined subtotal and gross-total resection rate was 95% (n = 40). Low-grade gliomas (LGGs; grades I and II) comprised one-third of the group, whereas half of the patients had glioblastoma multiforme. There were no operative mortalities. Although temporary postoperative motor deficits were observed in 12 patients (28.6%), all improved during the early postoperative period except 1 (2.4%), who had mild residual hemiparesis. Two patients required CSF diversion for hydrocephalus. The 2-year overall survival rate was 90% for LGG patients and 15% for high-grade glioma (HGG) patients. Multivariate analysis revealed that histological grade, age, and extent of resection were independent prognostic factors associated with survival. CONCLUSIONS: Management of TGs is challenging, with resection avoided by many, if not most, neurosurgeons, especially for HGGs. The results reported here demonstrate improved outcomes with resection, particularly in younger LGG patients. The authors therefore advocate for MSR for a select cohort of TG patients using carefully planned surgical approaches, contemporary intraoperative adjuncts, and meticulous microsurgical techniques.

Microsurgical anatomy and approaches to thalamic gliomas. Part 1: A cartography guide for navigating to the thalamus. Integrating 3D model rendering with anatomical dissections.

OBJECTIVE: The selection of appropriate microsurgical approaches to treat thalamic pathologies is currently largely subjective. The objective of this study was to provide a structured cartography map for surgical navigation to treat gliomas involving different surfaces of the thalamus. METHODS: Fifteen formalin-fixed, silicone-injected cadavers (30 sides) were dissected, and 10 adult brain specimens (20 sides) were used to illustrate thalamic microsurgical anatomy using the Klingler fiber dissection technique. Exposures and trajectories for the six most common microsurgical approaches were depicted using MR data from healthy subjects converted into surface-rendered 3D virtual brain models. Additionally, thalamic surfaces exposed with all six approaches were color mapped on the virtual 3D model and compared side-by-side in 360° views with previously reported microsurgical approaches. These 3D models were then used in conjunction with topographic data to guide cadaveric dissection steps. RESULTS: There are two general surgical routes to thalamic lesions: the subarachnoid transcisternal and transcortical routes. The transcisternal route consists of the following three approaches: 1) anterior interhemispheric transcallosal approach, which exposes the anterior and superior thalamus; 2) posterior interhemispheric transcallosal approach, which exposes the posterosuperior thalamus; and 3) supracerebellar infratentorial approach, which exposes the posteromedial cisternal thalamus and can be extended laterally to approach the posterolateral thalamus by cutting the tentorium. The three transcortical approaches are the 1) superior parietal lobule approach, which exposes the posterosuperior thalamus and is particularly advantageous in the setting of hydrocephalus; 2) transtemporal gyrus approach, which exposes the inferolateral thalamus; and 3) transsylvian transinsular approach, which exposes the lateral thalamus (slightly more superiorly and posteriorly) and is advantageous for pathologies extending laterally into the peduncle, lenticular nucleus, or insula. CONCLUSIONS: Microsurgical approaches to thalamic gliomas continue to be challenging. Nonetheless, safe and effective cisternal, ventricular, and cortical corridors can be developed with thoughtful planning, anatomical understanding, and knowledge of the advantages, risks, and limitations of each approach. In some cases, it is wise to combine these approaches with staged procedures, as the authors demonstrate in Part 2. In Part 1 of this two-part series, they discuss thalamic microsurgical anatomy and illustrate the trajectory and exposures of all six approaches to guide decision-making. Part 2 discusses their thalamic glioma microsurgical case series, which utilizes these microsurgical approaches.

Late recovery of stereotactic radiosurgery induced perilesional edema of an arteriovenous malformation after bevacizumab treatment.

MATERIALS AND METHODS: We present a 41-year old male patient who was admitted to our clinic with epileptic seizures, headaches and hemiparesis 14 months after SRS treatment for a left fronto-parietal Spetzler-Martin Grade III arteriovenous malformation (AVM). On his first-year follow-up perilesional edema was observed for which the patient received steroid treatment, but the patient did not show any benefit from it. In the cases of steroid resistant perilesional edemas, bevacizumab can be used for reducing symptoms and even radiological perilesional edema as well. RESULTS: In our case, we have seen the effect of bevacizumab for symptomatic perilesional edema in a AVM patient after SRS treatment after radiological / neurological recovery. Our patient's headaches decreased rapidly after 2 days after treatment and was able to mobilize himself after 2 months but total resolution of symptoms and radiological findings observed after 1,5 years. CONCLUSIONS: The duration and optimum dose of bevacizumab therapy needed to further investigation. Our study showed that bevacizumab was a long-term and effective treatment option for the cases with peritumoral edema resistant to glucocorticoid treatment, where the patient had conditions such as severe headache and neurological deficits.

A rare case report: Cervical subcutaneous and mediastinal emphysema due to mastoid fracture.

Subcutaneous emphysema occurs when air enters the soft tissue, which usually appears in the soft tissues of the chest wall or neck. It may also arise from pneumothorax or skin lacerations after trauma or other reasons. Mediastinal emphysema may be either associated with subcutaneous emphysema or seen alone. The air in the mastoid cells may spread from the retropharyngeal region or various neck compartments into the mediastinum. Usually, no severe neurological or clinical findings are observed except crepitation on palpation. We present a case report of a mastoid fracture as a rare cause of cervical subcutaneous and mediastinal emphysema.

Identification of Risk Factors for Postoperative Cerebrospinal Fluid Leakage and Comparison of Two Alternative Dural Augmentation Techniques in Posterior Fossa and Spinal Surgeries.

AIM: To investigate comparative efficacy of a novel absorbable adhesive membrane (TissuePatchDuralTM "TPD") and a fibrin glue (Tisseel "T") in reducing cerebrospinal fluid (CSF) leaks after posterior fossa and spinal procedures, and also to identify potential risk factors for CSF leakage. MATERIAL AND METHODS: This is a single-center, retrospective cohort study of 123 consecutive posterior fossa (n=77) and spinal (n=46) surgeries. Patients were grouped based on dural sealants used 2-group comparison: TPD (n=56) vs. no-TPD (n=67) and 3-group comparison: T only (n=43), TPD only (n=32) vs TPD+T (n=35). RESULTS: Mean age was 38.9 ± 22.2 years (62 males, 61 females). Baseline characteristics were similar between groups. Neither 2-group (TPD: 10.4% vs no-TPD: 8.9%; p=0.778) nor 3-group (T: 9.3% vs TPD: 6.3% vs TPD+T: 14.3%; p=0.539) comparisons revealed a significant difference in postoperative CSF leakage rates. Multivariate analysis showed that diagnosis (non-tumoral vs. tumor) (OR: 5.487; 95% CI: 1.118-26.937; p=0.036); previous surgery (OR: 9.268; 95% CI: 1.911-44.958; p=0.006), postoperative hydrocephalus (OR: 5.456; 95% CI: 1.250-23.821; p=0.024) were independent predictors of postoperative CSF leakage. CONCLUSION: TissuePatchDural < sup > TM < /sup > is a novel dural sealant patch which can be safely used to reinforce dural closure in posterior fossa and spinal surgeries, and its efficacy is comparable to widely used fibrin glue (Tisseel). Non-tumoral pathologies, previous surgery, and postoperative hydrocephalus appear to be independent risk factors for postoperative CSF leakage.

First emerging objective experimental evidence of hearing impairment following subarachnoid haemorrhage; Felix culpa, phonophobia, and elucidation of the role of trigeminal ganglion.

Objective: The exact mechanism of phonophobia induced by subarachnoid hemorrhage (SAH) has not been understood well. This subject was investigated. Material and methods: This study was conducted on 25 rabbits. They divided into three groups: Five as control, five as SHAM, 20 as SAH group. All animals objected to 85 dB impulse noise by daily periods, and their phonophobic score values were examined by daily periods for 20 days. Their brains, trigeminal ganglia were extracted bilaterally. The normal and degenerated neuron densities of trigeminal ganglia were examined by stereological methods and compared with phonophobia scores. Results: Phonophobic score was 19-17, mean live neuron density (LND) of the trigeminal ganglia was 16.321 ± 2.430/mm3, and degenerated neuron density (DND) was 1.15 ± 0.120/mm3 in animals of control groups (n = 5). The phonophobic score was 17-14, LND: 14.345 ± 1.913/mm3, DND of the trigeminal ganglia was 1.150 ± 0.110/mm3 in SHAM group (n = 5). The phonophobic score was 14-8, LND: 12.987 ± 1.966/mm3, mean DND of the trigeminal ganglia was 2.520 ± 510/mm3 in animals with high phonophobia scores (n = 6). The phonophobic score was 7-4, LND: 9.122 ± 1.006, mean DND of the trigeminal ganglia was 5.820 ± 1.610/mm3, in animals with fever phonophobia scores (n = 9). Conclusion: An inverse relationship between DND trigeminal ganglion (TGG) and phonopobic score was found. The paralysis of tensor tympani muscle owing to trigeminal ganglia ischemia may be responsible for phonophobic clinical state in animals with SAH. In addition, there seems to be an important concern for the verbal component of GCS in SAH. These two important findings have not been published previously.

Malignant Transformation of Vestibular Schwannoma After Stereotactic Radiosurgery.

Malignant transformation of vestibular schwannoma after stereotactic radiosurgery (SRS) is a fatal complication with a relatively less uncommon frequency over the past 5 years. Although SRS has been shown to be an alternative to microsurgical resection of vestibular schwannoma, this complication is disregarded most of the time. In this paper, we present a patient with left cerebellopontine angle vestibular schwannoma that was transformed into a malignant peripheral nerve sheath tumor after receiving SRS following microsurgical resection.

The Tonsillouvular Fissure Approach: Access to Dorsal and Lateral Aspects of the Fourth Ventricle.

OBJECTIVE: Although approaches to the fourth ventricle (FV) have been studied well, approaches to the lesions located in the dorsal and lateral aspects of the FV have not been shown in anatomic or clinical studies. The aim of this study is to show for the first time in the literature the tonsillouvular fissure approach (TUFA) in anatomic dissections and its use in surgical series. METHODS: For anatomic studies, 4 formalin-fixed human cadaveric heads infused with colored silicone and 10 cerebellar specimens were dissected in a stepwise manner. Records of 12 patients operated on via TUFA were also retrospectively reviewed. RESULTS: Neurosurgical anatomy and critical steps of TUFA were described in detail. Among 12 patients with lesions around the FV (4 cavernous malformation, 2 pilocytic astrocytoma, 2 hemangioblastoma, 1 B-cell lymphoma, 1 metastatic papillary carcinoma, 1 dermoid cyst, and 1 arteriovenous malformation), 11 gross total and 1 subtotal resection were achieved via TUFA without any mortality or morbidity. Comparative analyses of 4 surgical approaches to FV (TUFA, telovelar/cerebellomedullary fissure, supratonsillar/tonsillobiventral lobule fissure, and transvermian approaches) were also presented. CONCLUSIONS: TUFA provides a direct route and excellent surgical view to lesions around the FV, particularly on dorsal and lateral aspects, inferior vermis, and medial part of the dentate nucleus and cerebellar peduncles. It minimizes traversing the normal cerebellar tissue compared with a transvermian approach.

Calcifying Pseudoneoplasm of the Neuraxis (CAPNON) in Lateral Cerebellomedullary Junction: Clinical Image with Surgical Video.

Calcifying pseudoneoplasms of the neuraxis are rare, benign, slow-growing lesions, which occur anywhere in the central nervous system without any age or sex predilection. The lesion's clinical course is variable and poorly understood because a limited number of cases have been reported in the literature. In this report, we present a case of calcifying pseudoneoplasms of the neuraxis in the lateral cerebello-medullary junction, which was removed via a far-lateral approach. To best of our knowledge, this is the first report demonstrating actual lesions in a real-time surgical video, which may make the readers and viewers aware of such a pathology if they encounter this rare lesion.

Metastatic prostate adenocarcinoma to intradural foramen magnum.

Intradural metastatic tumors are rarely reported in foramen magnum (FM), including cases of melanoma, pituitary carcinoma, thyroid carcinoma, and prostate carcinoma metastases. We report a 68-year-old male who presented with right-sided headache, progressive swallowing difficulty requiring gastrostomy tube and hoarseness over the course of 1 year. Images revealed a heterogeneous, contrast-enhancing lesion in the FM that compressed the anterior aspect of the medulla and upper spinal cord. Although metastatic tumor was considered in differential diagnosis, presumptive diagnosis was FM meningioma due to lack of bone destruction or sclerosis on CT and T2W isointense and T1W hypointense appearance on MRI. The patient underwent gross total resection via right far-lateral transcondylar approach. Histopathological examination revealed prostate carcinoma metastasis. To the best of our knowledge this is the second case report of an intradural prostate carcinoma metastasis in the FM.