Effect of Fluid Therapy on Acid-Base Balance in Patients Undergoing Clipping for Ruptured Intracranial Aneurysm: A Prospective Randomized Controlled Trial.

Objectives Neurosurgical patients often receive 0.9% normal saline (NS) during the perioperative period. Theoretically, a balanced salt solution (BSS) is better than 0.9% saline. We compared the effects of two different fluids on acid-base balance, renal function, and neurological outcome in patients who underwent clipping following subarachnoid hemorrhage from a ruptured intracranial aneurysm. Materials and Methods Patients in group NS ( n = 30) received 0.9% saline and group BSS ( N = 30) received BSS (Plasmalyte-A) in the perioperative period for 48 hours. Comparison of arterial pH, bicarbonate, and base deficit measured preoperatively, intraoperatively (first and second hour), and postoperatively (at 24 and 48 hours) was the primary outcome of the study. The secondary outcome compared serum electrolytes, renal function tests, urine neutrophil gelatinase-associated lipocalin (NGAL), serum cystatin C, and the neurological outcome using modified Rankin score (MRS) at discharge, 1, and 3 months. Results In group NS, significantly low pH at 1-hour intraoperative period was seen compared with group BSS (7.37 ± 0.06 vs. 7.40 ± 0.05, p = 0.024). The bicarbonate level in group NS was significantly lower and the base deficit was higher at second intraoperative hour (bicarbonate: 17.49 vs. 21.99 mEq/L, p = 0.001; base deficit: 6.41 mmol/L vs. 1.89 mmol/L, p = 0.003) and at 24 hours post-surgery (bicarbonate: 20.38 vs. 21.96 mEq/L, p = 0.012; base deficit: 3.56 mmol/L vs. 2.12 mmol/L, p = 0.034)). Serum creatinine was higher in group NS at 24 hours (0.66 vs. 0.52 mg/dL, p = 0.013) and 48 hours (0.62 vs. 0.53 mg/dL, p = 0.047). Serum urea, electrolytes, cystatin, urine NGAL, and MRS were comparable. Conclusion In neurosurgical patients undergoing clipping for ruptured intracranial aneurysm, using a BSS during the perioperative period is associated with a better acid-base and renal profile. However, the biomarkers of kidney injury and long-term outcomes were comparable.

Interdural extra-arachnoidal resection of fifth nerve schwannomas with tailored petrous drilling: Eliminating the blind spot.

BACKGROUND AND OBJECTIVES: Around 20-40% of trigeminal schwannomas (TS) are dumbbell shaped, spanning the middle and posterior cranial fossa The petrous apex is often truncated in these patients, aiding surgical resection of both compartments through the middle fossa approach. However, a less eroded petrous creates a blind spot, making total resection difficult. This study describes the feasibility of an approach combining expanded Meckel cave access with tailored petrous bone drilling to optimize tumor visualization and resection. METHODS: Eleven patients with dumbbell TS and minimal petrous apex erosion underwent the described surgery. Surgical steps included temporo-orbito-zygomatic craniotomy, middle fossa floor drilling, navigation aided (tailored) extradural petrous bone drilling and extra-arachnoidal tumor excision. Extent of resection and postoperative outcomes were recorded. RESULTS: Patients presented with trigeminal nerve dysfunction (n = 9; sensory -9 and motor - 5), headache(8/11), ataxia (7/11) and pseudobulbar palsy (3/11). Complete tumor resection was achieved in all patients. Postoperatively, 8 out of 9 patients had transient increase in facial hypoesthesia with conjunctival injection in 3. It improved within 3-6 months, except in four cases wherein mild hypoesthesia persisted. Motor symptoms improved in 2 of 5 patients. Two developed transient 6th nerve paresis, that resolved in 2 months. Cerebellar and brainstem pressure symptoms resolved in all. No patients developed new onset permanent neurological deficit. Two patients reported mild post-craniotomy masticatory difficulty. CONCLUSIONS: The additional tailored petrous bony drilling enhances the surgeon's view, allowing a higher chance of total resection with no major operative morbidity.

Extended Unifrontal craniotomy for midline anterior cranial fossa meningiomas: A better shot at preservation of neurovascular structures.

Numerous surgical approaches have been described for the resection of anterior cranial fossa meningioma. The common problems associated with these approaches are excessive brain retraction, injury to neurovascular structures, transection of superior sagittal sinus (SSS), and a higher risk of new-onset anosmia. The authors describe a unilateral extended frontal approach with the aim to minimize brain handling without the need for SSS transection and possibly better olfaction preservation. METHODS: Thirteen patients with anterior cranial fossa meningioma were operated on using the novel technique of unilateral extended frontal skull base approach. The clinical presentation, radiological studies, intraoperative findings, and outcome at follow-up were recorded. RESULTS: Gross total tumor resection could be achieved in 12 out of 13 patients. At least one of the olfactory tracts could be anatomically preserved in all patients, and superior sagittal sinus was preserved in all patients. Functional olfaction preservation was achieved in 8 patients. No patient developed new-onset anosmia. CONCLUSIONS: The extended unilateral frontal approach is a viable and reliable alternative for extended bifrontal technique for the resection of large midline anterior cranial fossa meningiomas with avoidance of SSS ligation, decreased brain handling with better olfaction preservation while achieving comparable tumor resection and acceptable cosmetic outcomes.

Dysregulated Genes and Signaling Pathways in the Formation and Rupture of Intracranial Aneurysm.

Intracranial aneurysm (IA) has the potential to rupture. Despite scientific advances, we are still not in a position to screen patients for IA and identify those at risk of rupture. It is critical to comprehend the molecular basis of disease to facilitate the development of novel diagnostic strategies. We used transcriptomics to identify the dysregulated genes and understand their role in the disease biology. In particular, RNA-Seq was performed in tissue samples of controls, unruptured IA, and ruptured IA. Dysregulated genes (DGs) were identified and analyzed to understand the functional aspects of molecules. Subsequently, candidate genes were validated at both transcript and protein level. There were 314 DGs in patients with unruptured IA when compared to control samples. Out of these, SPARC and OSM were validated as candidate molecules in unruptured IA. PI3K-AKT signaling pathway was found to be an important pathway for the formation of IA. Similarly, 301 DGs were identified in the samples of ruptured IA when compared with unruptured IAs. CTSL was found to be a key candidate molecule which along with Hippo signaling pathway may be involved in the rupture of IA. We conclude that activation of PI3K-AKT signaling pathway by OSM along with up-regulation of SPARC is important for the formation of IA. Further, regulation of Hippo pathway through PI3K-AKT signaling results in the down-regulation of YAP1 gene. This along with up-regulation of CTSL leads to further weakening of aneurysm wall and its subsequent rupture.

Deceptive Appearances - Spastic Paretic Hemifacial Contractures in Cases of Seventh Nerve Involvement 'Inside' and 'Outside' the Brainstem.

Spastic paretic hemifacial contracture (SPHC) is a rare clinical phenomenon characterized by facial weakness and simultaneous well-sustained contraction of the unilateral half of the face, mimicking a paresis of the normal contralateral side on casual inspection. We present three cases with such phenomenon and have postulated the underlying mechanisms. One patient had intrinsic brainstem glioma, and the others were operated for extra-axial lesions compressing the pons. The former presented with SPHC, whereas the latter two gradually developed this phenomenon following postoperative facial paresis. This condition is possibly due to denervation hyper-excitability of the facial supranuclear pathway or an aberrant regeneration secondary to nerve injury leading to functional facial-nerve nuclear reorganization. SPHC occurrence is not limited to intra-axial lesions but can also be seen after partial injury to the facial nerve beyond its exit from the brainstem.

Ketofol as an Anesthetic Agent in Patients With Isolated Moderate to Severe Traumatic Brain Injury: A Prospective, Randomized Double-blind Controlled Trial.

BACKGROUND: The effects of ketofol (propofol and ketamine admixture) on systemic hemodynamics and outcomes in patients undergoing emergency decompressive craniectomy for traumatic brain injury (TBI) are unknown and explored in this study. METHODS: Fifty patients with moderate/severe TBI were randomized to receive ketofol (n=25) or propofol (n=25) for induction and maintenance of anesthesia during TBI surgery. Intraoperative hemodynamic stability was assessed by continuous measurement of mean arterial pressure (MAP) and need for rescue interventions to maintain MAP within 20% of baseline. Brain relaxation scores, serum biomarker-glial fibrillary acidic protein levels, and extended Glasgow Outcome Scale (GOSE) at 30 and 90 days after discharge were also explored. RESULTS: MAP was lower and hemodynamic fluctuations more frequent in patients receiving propofol compared with those receiving ketofol (P<0.05). MAP fell >20% below baseline in 22 (88%) patients receiving propofol and in 10 (40%) receiving ketofol (P=0.001), with a greater requirement for vasopressors (80% vs. 24%, respectively; P=0.02). Intraoperative brain relaxation scores and GOSE at 30 and 90 day were similar between groups. Glial fibrillary acidic protein was lower in the ketofol group (3.31±0.43 ng/mL) as compared with the propofol (3.41±0.17 ng/mL; P=0.01) group on the third postoperative day. CONCLUSION: Compared with propofol, ketofol for induction and maintenance of anesthesia during decompressive surgery in patients with moderate/severe TBI was associated with improved hemodynamic stability, lower vasopressor requirement, and similar brain relaxation.

A Novel Pedicle Screw Design with Variable Thread Geometry: Biomechanical Cadaveric Study with Finite Element Analysis.

BACKGROUND: Pedicle screw fixation provides one of the most stable spinal constructs. Their designs together with osseous characteristics have been known to influence the screw-bone interplay during surgical maneuvers and thereafter the fusion process. Various technical modifications to enhance screw performance have been suggested. This study evaluated the pull-out strength and axial stiffness of a novel pedicle screw design with variable thread geometry and pitch. METHODS: The newly designed triple threaded pedicle screw is tapered, and has unique out-turned flanges to hold the cancellous bone and a finer pitch at its distal and proximal end to engage the cortical bone. Five lumbar and 4 lower thoracic cadaveric vertebrae were divided into hemivertebrae. A standard cancellous pedicle screw and the newly designed pedicle screw were inserted into each hemivertebra. Axial stiffness and peak pull-out force between the screw types were compared; a finite element analysis was also performed to additionally compare the pull out under toggle forces. RESULTS: In cadaveric study, the axial stiffness of the new screw was significantly better than that of the standard screw. However, the peak load between the screws was not statistically different. Finite element analyses suggested lesser stress at bone-implant interface for the new screw along with better axial stiffness under both co-axial and toggle forces. CONCLUSIONS: Our novel pedicle screw design with variable thread geometry demonstrates greater axial stiffness compared with the standard screws, and therefore is likely to withstand a greater surgical manipulation.

Technique of C2 Nerve Root Preservation in the Presence of Anomalous Vertebral Artery in Atlantoaxial Operations.

While accessing the C1-C2 joint during posterior atlantoaxial fixation, the C2 nerve root along with its perineural venous plexus remains an obstacle for a panoramic visualization of the entry point of the C1 lateral mass and joint preparation. Therefore, many surgeons frequently advocate its intentional sectioning during this approach, with no related major complications.1,2 However, this sectioning has at times been associated with symptoms such as hypoesthesia, numbness, dysesthesia, and neuropathic ulcers.3 Thus C2 nerve root preservation during posterior approach for atlantoaxial dislocation (AAD) could potentially avoid such consequences.4 Its preservation has been described for AAD cases with relatively normal C1-C2 joint anatomy with no osseovascular abnormalities.2 In contrast, attempt at C2 nerve root preservation in patients with congenital AAD harboring bony and vascular anomalies poses a greater challenge owing to a restricted operative space and the potential for perineural venous bleeding during dissection. This is more so for young neurosurgeons in the initial part of their learning curve. Video 1 details the technique of C2 nerve root dissection and preservation in a case of congenital AAD with an anomalous vertebral artery (VA). Computed tomography (CT) of this 30-year-old male patient with spastic quadriparesis showed AAD/basilar invagination with an assimilated C1-arch and right anomalous VA on CT angiography. He underwent C1-C2 joint manipulation and short-segment fixation. At 1-year follow-up, the patient's limb weakness had improved and CT showed good bony fusion. The salient operative steps involve gentle teasing and dissection of perineural soft tissues above and below the nerve root; the key to minimize venous bleeding is to dissect, coagulate, and divide them sequentially. A thorough release of the perineural soft tissues allows adequate nerve root mobilization, which in turn provides clear visualization of the C1-C2 joint space, preventing an undue nerve stretching during the C1-lateral mass screw insertion. The anomalous VA usually lies anterior to the C2 nerve root, and careful imaging evaluation allows its anticipation.3 We do not prefer the easy alternative of C2 nerve root sacrifice because of its inherent complications we noticed in our earlier clinical practice.3.

Evaluation of the changes in middle cerebral artery flow velocity related to different positions of patients during posterior fossa surgery.

Background: This is a prospective observational study to evaluate the changes in middle cerebral artery flow velocities and cerebral perfusion pressure in the various positions used for posterior cranial fossa surgery and to correlate these changes with postoperative recovery characteristics and complications. Methods: Sixty patients were included in the study - 33 patients with CPA tumors were placed in the supine with head tilt position and the rest 27 with tumors in other locations of posterior fossa were placed in the prone position. The primary aim was to study the changes in middle cerebral artery blood flow velocity related to various positions of the patients used during posterior fossa surgery. The secondary aim was to compare the changes in pulsatility index, resistance index, and effective cerebral perfusion pressure in different position and to correlate these findings with postoperative recovery and the complications associated with these positions. Results: The systolic and mean flow velocities were higher in the supine with head tilt group than the prone group after positioning and post repositioning, but these values were within normal limits, and the changes with positioning from baseline were comparable between the groups. Furthermore, these changes did not affect the effective cerebral perfusion pressure or the outcomes of the patients. Conclusion: The current results do not determine whether the supine with head tilt position is better than the prone position during posterior fossa surgery.

C1-C2 arthroplasty for craniovertebral junction instability: A preliminary proof of concept in human cadavers.

Background: The atlantoaxial complex contributes to significant neck movements, especially the axial rotation. Its instability is currently treated with various C1-C2 fusion techniques. This however, considerably hampers the neck movements and affects the quality of life; a C1-C2 motion preserving arthroplasty could potentially overcome this drawback. Objectives: We evaluate the range of motion (ROM) of lateral C1-C2 artificial joints in cadaveric models. Materials and Methods: This is an in vitro cadaveric biomechanical study. After C1-C2 arthroplasty through a posterior approach, the C1-C2 ROM was tested in 4 fresh-frozen human cadaveric specimens, before and after destabilization. Results: The mean axial rotation demonstrated after the placement of C1-C2 joint implants was 15.46 degrees on the right and 16.03 degrees on the left side; the prosthesis provided stability, with 46% of the baseline C1-C2 axial rotation on either side. The ROM achieved in the other axes was less compared with that of intact specimens. To initiate rotation, a higher moment of 1.5 Nm was required in the presence of joint implants compared to 0.5 NM in unimplanted specimens. Conclusions: In our preliminary ROM evaluation, the C1-C2 arthroplasty appears to be stable and provides about half of the range of atlantoaxial rotation. It has the potential for joint motion preservation in the treatment of atlantoaxial instability resulting from lateral C1-C2 joint pathologies.

IgG4-related Pachymeningitis as a Cause of Spinal Epidural Compression: Can Intraoperative Frozen Sections Predict the Underlying Pathology?

At times, spinal lesions are part of systemic manifestations of autoimmune disease. Awareness regarding their clinicopathological spectrum, particularly the lesions which usually respond to steroids/immunotherapy, is essential to avoid unwanted surgical morbidity. We discuss a case of a young-man presenting with thoracic spinal epidural compressive lesion which was indeed a manifestation of IgG4-related hypertrophic pachymeningitis. The mass was firmly adherent to the dura and extended into left neural foramen/paravertebral space which precluded complete excision. Frozen sections suggested fibro-inflammatory stroma with large areas of fibrosis and lymphoplasmacytic infiltrate. After subtotal excision, the patient improved with medical therapy at 1-year follow-up. Although uncommon, the case highlights the need to consider spinal presentation of this rare entity, especially in the context of autoimmune disorders or even in isolation. In this regard, intraoperative frozen section can hint the underlying inflammatory/autoimmune pathology, guide further course of surgery as well as limit unwarranted operative morbidity.

Revisiting Surgery in the Current Era of Gamma Knife for Cavernous Sinus Lesions.

Background: The challenges associated with surgeries of cavernous sinus (CS) lesions have shifted the management trend towards upfront gamma knife radiosurgery (GKRS). Although GKRS is effective in arresting the progression of certain small residual/recurrent lesions, its efficacy in alleviating neurological deficits is less evident. Furthermore, GKRS without establishing the histopathological diagnosis, at times can be detrimental. Objective: We present our clinical experience to reemphasize the role of surgery for CS lesions in the current era of upfront GKRS. Materials and Methods: We reviewed our database of 32 patients with various CS lesions treated by surgery for progressive cranial nerve deficits. The follow-up data were analyzed for the extent of resection, and in particular for improvement in their symptoms. Results: The lesions were confirmed as hemangioma (CSH)-8, meningioma-8, trigeminal schwannoma-6, chordoma-3, residual pituitary with CS extension-3, fungal granuloma-3, and dysgerminoma-1. Symptoms improved in 23 (complete in 13) and remained at least static in six patients. Follow-up ranged from 4-36 months. Conclusions: The nature of pathology should determine the management modality in CS lesions. Excision of CS schwannomas and chordomas yields rapid clinical improvement and good long-term outcomes. Resection is preferred for large CSH and functioning pituitary tumors. Although the clinical improvement may be less dramatic, surgery debulks the meningiomas. Most importantly, surgery also establishes the histopathological diagnosis of CS lesions. Even with an easy alternative of upfront GKRS, resection has a definite role in the primary management of most CS pathologies.

Setting up a Neurosurgical Skills Laboratory and Designing Simulation Courses to Augment Resident Training Program.

Background: The surgical skill practice in neurosurgery is being compromised in the recent past owing to the duty time constraint, patient safety concerns, and medico-legal issues. Surgical practice outside the operating room is essential to enhance a resident's operative skills and to gain confidence. Objective: To discuss the experience of establishing an 'in-house neurosurgery skills laboratory' and various training sessions conducted with cadaveric and non-cadaveric simulation modules. Methods: A skills laboratory was set up in the existing resident teaching hall with nine workstations. Each station has been equipped with an operating table, surgeon's chair, basic microscope, endoscope, high-speed drill system, and a suction machine. Vascular anastomosis, high-speed drilling, and basic neuroendoscopy were planned on low-cost non-cadaveric modules. Craniotomy and various surgical approaches were designed on cadaveric modules obtained from the anatomy department. Result: A total of 18 residents in divided groups during their initial three semesters had participated in the non-cadaveric simulation courses. Twenty-six residents had participated and 12 sessions were conducted on the cadaveric modules. Three workshops were conducted and 20 residents and faculty members from five other institutions had participated in the cadaveric hands-on training session. Conclusion: A well-equipped skills laboratory provides an opportunity for the residents to acquire operative expertise in a similar atmosphere to that of the operating theater. A structured program comprising various operative practice sessions should be incorporated into the resident training program.

Cerebrospinal fluid cytology in a toddler with a posterior fossa space-occupying lesion.

An atypical teratoid rhabdoid tumour (AT/RT) is an extremely rare malignant neoplasm. Cerebrospinal fluid (CSF) involvement at presentation indicates intracranial dissemination and is associated with an aggressive course and worse outcomes. We present the characteristic cytomorphological features of AT/RT in the cerebrospinal fluid from a toddler presenting with a posterior fossa space-occupying lesion.

Extra-axial, dural-based atypical teratoid/rhabdoid tumor.

Atypical teratoid/rhabdoid tumors (ATRTs) are malignant central nervous system tumors that affect early childhood (< 3 years), and mostly located in the infratentorial space. Owing to an infrequent occurrence, their radiological features have not been completely defined. Nevertheless, these are characteristically intra-axial except for few instances in the cerebellopontine angle region. We describe a case of a 10-year-old boy who harbored an extra-axial, dural-based ATRT in the right parietal region. The lesion was totally excised followed by adjuvant chemo-radiotherapy. At 10-month follow-up, he was well with no recurrence. The report intends to highlight an atypical imaging presentation of ATRT in an older child, and adds to the radiological spectrum. This uncommon pathology should be borne in mind, even in a supratentorial dural-based location.

Multiple Fusarium brain abscesses in a young child.

Isolated intracranial fungal infection is infrequent and mostly seen in high-risk, immunocompromised patients. Fusarium, a primary plant fungus, rarely contributes to such disease. Amongst the very few cases of Fusarium brain abscess that have been reported, the infection has occurred mostly in adults. We present a case of a 6-year-old boy with tuberculous meningitis diagnosed with multiple Fusarium brain abscess caused by Fusarium falciforme during his clinical course. An immunocompromised state secondary to tuberculous meningitis presumably led to this infection. After tapping the abscesses, the child was treated with a combination of amphotericin B, voriconazole and terbinafine. Despite an aggressive therapy, he remained in poor neurological state. This is the second report of an isolated Fusarium abscess in pediatric age and the first one in a young child and provides pertinent review of this unusual central nervous system fungal infection. Such unusual infectious spectrum should be borne in mind in patients with co-existent immunosuppression.

C2 Nerve Root Preservation During Posterior Fixation for Instability Secondary to Congenital Craniovertebral Junction Anomalies: Feasibility Factors and Related Outcomes.

OBJECTIVE: Patients with instability because of congenital craniovertebral anomalies often have complex C1-C2 osseovascular anomalies. C2 nerve root sacrifice has been described to address such difficult anatomy during posterior C1-C2 fixation and has its own downsides. Its preservation as a recent alternative poses greater surgical challenge, and the considerations differ from other causes of craniovertebral junctional instability; the pertaining outcomes have been scarcely studied. The objective of this study was to prospectively determine the feasibility and outcomes related to C2 nerve root preservation in patients with congenital atlantoaxial dislocation (CAAD) after posterior C1-C2 fixation. METHODS: In this observational study, 63 patients (126 nerve roots) with CAAD after posterior fixation were prospectively assessed. Underlying osseovascular anomalies affecting the feasibility of C2 nerve root preservation, and C2 nerve-related dysfunction at 12 months follow-up were analyzed. RESULTS: The overall C2 nerve root preservation rate was 89.7%. Even in the presence of extreme joint obliquity/spondyloptosis and anomalous vertebral artery, it was feasible in about three fourths. After preservation, 28.3% patients developed new-onset C2 nerve root dysfunction: neuralgia in 2, dysesthesia in 6, and hypoesthesia/paresthesia in 9. The symptoms were not disabling in most patients. CONCLUSIONS: In most patients with CAAD, C2 nerve root preservation is feasible despite an aberrant bony and vascular anatomy. A few patients after nerve root preservation develop related symptoms that are conservatively manageable, with no significant adverse consequences. Given the controversy in the literature on C2 nerve sacrifice-related outcomes, we favor an attempt at C2 nerve root preservation.