Development of shunt valves used for treating hydrocephalus: comparison with endoscopy treatment.

The pathophysiology of hydrocephalus is not clearly defined. Thus, treatment will remain empirical until a fuller understanding of the various forms of hydrocephalus is achieved. Valve-controlled shunting has been the mainstay of therapy since the late 1950s. Initially, shunting occurred from the ventricular system to the atrium. In the 1970s, VA shunts were replaced by ventriculoperitoneal shunts as the primary location for the distal end. Multiple types of one-way valve systems have been developed in the pursuit of draining the appropriate amount of CSF that avoids either overdrainage or underdrainage while preserving normal brain development and cognition. These valves are reviewed and compared as to their function. Other locations for the distal end of the shunting system are reviewed to include pleural space and gallbladder. The lumbar subarachnoid space as the proximal location for a shunt is also reviewed. The only other surgical alternative for treating hydrocephalus is endoscopic third ventriculostomy. Since 2000, approximately 50% of children with hydrocephalus have been shown to be candidates for ETV. The benefits are the lack of need for an artificial shunt system and thus lower rates of infection and over time fewer reoperations. Future progress is dependent on improved shunt valve systems that are affordable worldwide and ready availability of ETV in developing countries. Anatomic and molecular causes of hydrocephalus need to be defined so that medications or genetic modifications become available for potential cure of hydrocephalus.

The effect of shunt removal on the quality of life in patients with congenital hydrocephalus.

BACKGROUND: Although there have been reports investigating the quality of life of patients who underwent ventriculoperitoneal shunting or endoscopic third ventriculostomy (ETV) for congenital hydrocephalus, there have been no studies of the quality of life of patients after ventriculoperitoneal shunt (VPS) removal. In the present study, a survey of pediatric and congenital hydrocephalus patients was conducted to compare the quality of life of patients with a remaining VPS with that of patients who had the shunt removed. METHODS: Between February 2020 and November 2021, an outpatient survey was administered to patients 8 years of age and older who had undergone VPS due to a diagnosis of congenital hydrocephalus. The Hydrocephalus Outcome Questionnaire (HOQ) was used to assess the quality of life for this study. The HOQ scores (overall health score, physical health score, cognitive health score, and social-emotional health score) were compared among three groups: a VPS-remaining group, VPS-removed with endoscopic third ventriculostomy (ETV) group, and VPS-removed without ETV group. RESULTS: The total number of patients who underwent VPS for hydrocephalus was 71, with 47 in the VPS-remaining group, 14 in the shunt-removed with ETV group, and 10 in the shunt-removed without ETV group. The HOQ overall health score was 0.68 for the VPS-remaining group, 0.74 for the shunt-removed with ETV group, and 0.74 for the shunt-removed without ETV. There were no significant differences between the VPS-remaining group and the VPS-removed with or without ETV groups (p = 0.3255, 0.4178, respectively). CONCLUSION: There was no significant difference in the quality of life between patients with a remaining VPS and those who had their VPS removed with or without ETV.

Endovascular Management of a Basilar Artery Pseudoaneurysm After Iatrogenic Injury During Endoscopic Third Ventriculostomy: Case Report.

Endoscopic third ventriculostomy (ETV) is a well-established neurosurgical procedure. However, it carries risks of intraoperative complications, among which major vascular injury is the most dangerous. Reportedly, prominent bleeding during ETV has been noted in <1% of cases. Herein, we describe a case of a 34-year-old woman with occlusive hydrocephalus caused by a quadrigeminal cistern arachnoid cyst, who developed a pseudoaneurysm after injury of the basilar artery apex during ETV. Complete obliteration of the pseudoaneurysm with endovascular balloon-assisted coiling was done on the first postoperative day, and the patient demonstrated gradual recovery, but approximately 4 weeks later, she suffered massive rebleeding, seemingly due to rupture of the weak pseudoaneurysm wall, which resulted in her death. Careful evaluation of sagittal T2-weighted magnetic resonance images before ETV may be invaluable for assessment of the basilar artery position in relation to the third ventricle floor. In addition, use of a blunt surgical instrument (instead of a sharp one or cautery) for fenestration may be safer for prevention of arterial injury. Finally, special care should be applied in cases with an opaque third ventricle floor and inability to visualize the basilar artery during ETV.

Ventricular CSF proteomic profiles and predictors of surgical treatment outcome in chronic hydrocephalus.

BACKGROUND: By applying an unbiased proteomic approach, we aimed to search for cerebrospinal fluid (CSF) protein biomarkers distinguishing between obstructive and communicating hydrocephalus in order to improve appropriate surgical selection for endoscopic third ventriculostomy vs. shunt implants. Our second study purpose was to look for potential CSF biomarkers distinguishing between patients with adult chronic hydrocephalus benefitting from surgery (responders) vs. those who did not (non-responders). METHODS: Ventricular CSF samples were collected from 62 patients with communicating hydrocephalus and 28 patients with obstructive hydrocephalus. CSF was collected in relation to the patients' surgical treatment. As a control group, CSF was collected from ten patients with unruptured aneurysm undergoing preventive surgery (vascular clipping). RESULTS: Mass spectrometry-based proteomic analysis of the samples identified 1251 unique proteins. No proteins differed significantly between the communicating hydrocephalus group and the obstructive hydrocephalus group. Four proteins were found to be significantly less abundant in CSF from communicating hydrocephalus patients compared to control subjects. A PCA plot revealed similar proteomic CSF profiles of obstructive and communicating hydrocephalus and control samples. For obstructive hydrocephalus, ten proteins were found to predict responders from non-responders. CONCLUSION: Here, we show that the proteomic profile of ventricular CSF from patients with hydrocephalus differs slightly from control subjects. Furthermore, we find ten predictors of response to surgical outcome (endoscopic third ventriculostomy or ventriculo-peritoneal shunt) in patients with obstructive hydrocephalus.

Mortality and complications 1 year after treatment of hydrocephalus with endoscopic third ventriculostomy and ventriculoperitoneal shunt in children at Queen Elizabeth Central Hospital, Malawi.

BACKGROUND: Over the past two decades, the management of hydrocephalus has witnessed the addition of endoscopic third ventriculostomy with or without choroid plexus cauterization (ETV ± CPC) to the traditional methods including ventriculoperitoneal shunt insertion (VPSI). We conducted this study to assess mortality and complications with surgical implications associated with the two procedures in children with hydrocephalus. METHODS: We reviewed our operating theater registry to identify children below 17 years old who underwent hydrocephalus surgery for the first time in 2016. The patients were followed for up to 1 year from the date of the initial operation. Their vital status was confirmed by follow-up visits by a community nurse. Descriptive analyses were used to describe the characteristics of the patients and evaluate the study outcomes (i.e., mortality and complications). RESULTS: One hundred fifty-three patients were eligible for the study; 56% were males and 73.2% had primary ETV ± CPC. Complete 1-year follow-up data was available for 79 patients, and 73.4% of these had ETV ± CPC. One-year success (event-free) rates for ETV and VPSI were similar at 67.4% and 66.7%, respectively. ETVs in infants under 6 months performed poorly; failing in half the infants, who were subsequently converted to VPS. Shunt sepsis was very high, 21.4% (95% CI 10.3-36.8). The majority of surgical complications (81.8%) occurred within 3 months of surgery. CONCLUSION: ETV ± CPC and VPSI carry a similar frequency of mortality and complications in our setting, and therefore, both should be considered as a treatment option for patients with hydrocephalus. As VP shunt is still used for managing most of the patients, there is still a need to prioritize measures to reduce shunt infections.

Neuronavigated foraminoplasty, shunt removal, and endoscopic third ventriculostomy in a 54-year-old patient with third shunt malfunction episode: how I do it.

BACKGROUND: The application of endoscopic third ventriculostomy (ETV) for the treatment of obstructive hydrocephalus in shunt malfunction represents a paradigm shift, as it allows hydrocephalus to be transformed from a chronic condition treated with an artificial device to a curable disease. METHODS: We present a 54-year-old male with a diagnosis of idiopathic Sylvian aqueduct stenosis treated with shunt. The patient presented to our institution with symptoms of shunt malfunction and an increase in ventricular size on imaging, which was his third episode throughout his life. Through a right precoronal approach, with prior informed consent from the patient, we performed foraminoplasty, endoscopic third ventriculostomy, and finally removal of the shunt system. CONCLUSION: ETV shows promise as a viable treatment option for shunt malfunction in noncommunicating obstructive hydrocephalic patients. Its potential to avoid VPS-related complications, preserve physiological CSF circulation, and provide an alternative drainage pathway warrants further investigation.

A rare case of intralesional haemorrhage of a benign aqueductal cyst after CSF diversion treatment. A case report and review of literature.

Benign cysts within the pure aqueductal region are a rare entity. Their critical location within the ventricular system presents a risk of potentially catastrophic outcomes. We present a case of a 68-year-old female who was transferred to our unit with an acute obstructive triventricular hydrocephalus caused by a benign cyst within the cerebral aqueduct. She became unconscious and had an urgent endoscopic third ventriculostomy (ETV). Post-operatively, the patient was recovering well but then developed a sudden onset severe headache accompanied by vomiting. Imaging revealed intracystic haemorrhage with expansion of lesion but there was no obstructive hydrocephalus due to CSF diversion performed 9 d prior. She was treated conservatively and continued to improve.

Agenesis of the right internal carotid artery and aqueductal stenosis in a child with hydrocephalus, the role of endoscopic third ventriculostomy: a case report.

Agenesis of the internal carotid artery (aICA) is a rare congenital vascular condition that can affect one or both sides of the patient. Most patients remain asymptomatic, but ischemic/hemorrhagic stroke, intracranial aneurysm, and other neurologic findings can occur. CT scan can demonstrate the absence of the bony carotid canal and helps to differentiate a complete aICA from aplasia or hypoplasia. The association of aICA and aqueductal stenosis (AS) has never been reported in the literature. We report the case of a 9-year-old with agenesis of the right ICA associated with AS and hydrocephalus, which was treated successfully with an endoscopic third ventriculostomy (ETV). We review the literature looking for the association of the clinical findings and the evolution of the patient.

Effect of a bundle approach on external ventricular drain-related infection.

BACKGROUND: Emergency placement of an external ventricular drain (EVD) is one of the most frequently performed neurosurgical procedures. EVD-related infection continues to be a major challenge causing significant morbidity and costs. Bundle approaches have been shown to reduce infection rates; however, they are still not widely used, and observation periods often were rather short. METHODS: The present study evaluated the effect of a multi-item bundle approach for EVD placement and care on the occurrence of EVD-related infection. A before/after approach was used to compare groups of consecutive patients over 5-year epochs to control for bias and secondary confounding variables. RESULTS: The number of patients in the group before implementation of the bundle approach was 141 and 208 thereafter. There were no statistical differences in demographic and other variables. While 41/141 patients (29.1%) had an EVD-related infection before, this was the case in only 10/208 patients (4.8%) thereafter (p < 0.0001). The EVD-related infection rate was reduced from 13.7/1000 catheter days to 3.2/1000, and the 50% probability of an EVD-related infection in correlation to the mean duration of EVD placement was significantly lower (p < 0.0001). Routine EVD replacement was not helpful to reduce EVD-related infection. EVD-related infection rates remained low also over the next 8 years after the study was finished. CONCLUSIONS: The introduction of a multi-item bundle approach for EVD insertion and care resulted in a marked reduction of EVD-related infection. Long observation periods over 5 years and beyond confirm that short-term changes are sustained with continued use of such protocols.

Implementation of cisternostomy as adjuvant to decompressive craniectomy for the management of severe brain trauma.

OBJECTIVE: To evaluate the value of an adjuvant cisternostomy (AC) to decompressive craniectomy (DC) for the management of patients with severe traumatic brain injury (sTBI). METHODS: A single-center retrospective quality control analysis of a consecutive series of sTBI patients surgically treated with AC or DC alone between 2013 and 2018. A subgroup analysis, "primary procedure" and "secondary procedure", was also performed. We examined the impact of AC vs. DC on clinical outcome, including long-term (6 months) extended Glasgow outcome scale (GOS-E), the duration of postoperative ventilation, and intensive care unit (ICU) stay, mortality, Glasgow coma scale at discharge, and time to cranioplasty. We also evaluated and analyzed the impact of AC vs. DC on post-procedural intracranial pressure (ICP) and brain tissue oxygen (PbO2) values as well as the need for additional osmotherapy and CSF drainage. RESULTS: Forty patients were examined, 22 patients in the DC group, and 18 in the AC group. Compared with DC alone, AC was associated with significant shorter duration of mechanical ventilation and ICU stay, as well as better Glasgow coma scale at discharge. Mortality rate was similar. At 6-month, the proportion of patients with favorable outcome (GOS-E ≥ 5) was higher in patients with AC vs. DC [10/18 patients (61%) vs. 7/20 (35%)]. The outcome difference was particularly relevant when AC was performed as primary procedure (61.5% vs. 18.2%; p = 0.04). Patients in the AC group also had significant lower average post-surgical ICP values, higher PbO2 values and required less osmotic treatments as compared with those treated with DC alone. CONCLUSION: Our preliminary single-center retrospective data indicate that AC may be beneficial for the management of severe TBI and is associated with better clinical outcome. These promising results need further confirmation by larger multicenter clinical studies. The potential benefits of cisternostomy should not encourage its universal implementation across trauma care centers by surgeons that do not have the expertise and instrumentation necessary for cisternal microsurgery. Training in skull base and vascular surgery techniques for trauma care surgeons would avoid the potential complications associated with this delicate procedure.

Higher Failure of Endoscopic Third Ventriculostomy in Infants: The "Distensible" Skull Is the Culprit.

The efficacy of endoscopic third ventriculostomy (ETV) in childhood strongly correlates with age. Reasons for the higher failure rate in infants are under debate but the "distensible" head with its immature skull (which would prevent an adequate flow through the ETV and/or a sufficient pressure gradient between the cortical subarachnoid spaces and the venous sinuses) has been suggested as a possible cause. Our evidence of spontaneous conversion of a failed, but always patent, third ventriculostomy into an effective one occurring in a child after maturation of the skull supports this hypothesis.

Supraorbital subfrontal trans-laminar endoscope-assisted approach for tumors of the posterior third ventricle.

BACKGROUND: Different surgical approaches have been developed for dealing with third ventricle lesions, all aimed at obtaining a safe removal minimizing brain manipulation. The supraorbital subfrontal trans-lamina terminalis route, commonly employed only for the anterior third ventricle, could represent, in selected cases with endoscopic assistance, an alternative approach to posterior third ventricular lesions. METHODS: Seven patients underwent a supraorbital subfrontal trans-laminar endoscope-assisted approach to posterior third ventricle tumors (two craniopharyngiomas, one papillary tumor of the pineal region, one pineocytoma, two neurocytomas, one glioblastoma). Moreover, a conventional third ventriculostomy was performed via the same trans-laminar approach in four cases. RESULTS: Complete tumor removal was accomplished in four cases, subtotal removal in two cases, and a simple biopsy in one case. Adjuvant radiotherapy and/or chemotherapy was administered, if required, on the basis of the histologic diagnosis. No major complications occurred after surgery except for an intratumoral hemorrhage in a patient undergoing a biopsy for a glioblastoma, which simply delayed the beginning of adjuvant radiochemotherapy. No ventriculoperitoneal shunt placement was needed in these patients at the most recent clinical and radiologic session (average 39.57 months, range 13-85 months). Two illustrative cases are presented. CONCLUSIONS: The supraorbital subfrontal trans-laminar endoscope-assisted approach may provide, in selected cases, an efficient and safe route for dealing with posterior third ventricular tumors.

Ventricular volume and neurocognitive outcome after endoscopic third ventriculostomy: is shunting a better option? A review.

BACKGROUND: Shunts are generally associated with a smaller post-treatment ventricular size in comparison to endoscopic third ventriculostomy (ETV). METHODS: To determine whether such a difference in ventricular size has neurocognitive implications, we reviewed the current literature pertaining to the (1) neurocognitive sequelae of hydrocephalus, (2) neurocognitive outcome after ETV, (3) extent of reversal of neurocognitive changes associated with hydrocephalus after shunting, and (4) data on correlation between post-treatment ventricular volume and neurocognitive outcome after ETV. RESULTS: Collectively, the results of the available studies should call into question the correlation between the residual postoperative ventricular volume and neurocognitive outcome. CONCLUSION: The available literature is so far in support of ETV as a valid and effective treatment modality in hydrocephalic patients. No sufficient evidence is available to justify resorting to shunting on the premise that it is associated with a better neurocognitive outcome.

Risk of Ventriculostomy-Associated Hemorrhage in Patients with Aneurysmal Subarachnoid Hemorrhage Treated with Anticoagulant Thromboprophylaxis.

BACKGROUND: Patients with subarachnoid hemorrhage (SAH) frequently need a ventriculostomy for treatment of hydrocephalus. In some ICU practices, a ventriculostomy is considered a relative contraindication for subcutaneous heparin. We studied the risk of ventriculostomy-associated hemorrhage and deep venous thrombosis (DVT) in patients with anticoagulant prophylaxis. METHODS: This is a retrospective study of 241 consecutive patients with SAH and ventriculostomies treated at Mayo Clinic, Rochester from 2001 to 2014. DVT and pulmonary emboli (PE) prevention included subcutaneous or intravenous heparin, enoxaparin, dalteparin, and warfarin. The incidence of PE and DVT were noted within 30 days of hospital admission. Hemorrhages were classified as minor or major based on size and mass effect. RESULTS: Fifty-three (22 %) of the 241 patients were on prophylactic doses of anticoagulation while in the intensive care unit. Three of 53 patients on prophylactic anticoagulation had minor hemorrhages and none had major hemorrhages. Four (7.5 %) of 53 patients who received prophylactic anticoagulation versus 34 (18 %) of 188 patients who did not receive prophylactic anticoagulation developed DVT (p = 0.09). One of 10 patients on therapeutic anticoagulation had a major and fatal hemorrhage. CONCLUSION: In our cohort, the risk of VTE was reduced by more than half in patients receiving chemoprophylaxis. Ventriculostomy-associated hemorrhages were rare and minor. Anticoagulant thromboprophylaxis is mostly safe and required in aneurysmal SAH.

Endoscopic third ventriculostomy in obstructive hydrocephalus: surgical technique and pitfalls.

BACKGROUND: Reviewing our experience in the variety of pathological entities causing obstructive hydrocephalous, we evaluate the effectiveness of endoscopic treatment, with particular attention to surgical technique, nuances, and pitfalls. MATERIALS AND METHODS: We reviewed the cases of 57 consecutive patients with obstructive hydrocephalus of various origins in the last 9 years. They were treated by endoscopic third ventriculostomy (ETV). A septostomy was also performed in ten cases. Operative videos were reassessed, and surgical nuances reconsidered. RESULTS: ETV was accomplished in all but three cases. The overall rate of good results (shunt-independent patients with clinical remission or improvement) was 81.5% (44/54). From ten patients with ETV failure, five were re-ETVed successfully, and five were shunted. Patients with benign aqueductal stenosis and tumor compressing the aqueduct received the greatest benefit from the ETV. There were no permanent morbidities or any mortality. Fundamentals of preoperative planning, postoperative evaluation, and technical pitfalls have been considered. CONCLUSION: ETV for obstructive hydrocephalus of various origins is safe and effective, and should be considered as a first-line treatment. Familiarity with the ventricular anatomy and its variations in hydrocephalus is key to success. Preoperative planning is mandatory. Awareness of potential pitfalls minimizes the risk.

Hidden aqueductal stenosis associated to bilateral idiopathic foramina of Monro stenosis mimicking a Chiari I malformation? Case report.

A 39-year old man came to our outpatient clinic with long history of unspecific symptoms and signs. Cerebral MRI showed herniation of the cerebellar tonsils of more than 1 cm below the foramen magnum and a triventricular hydrocephalus. A diagnosis of Chiari I malformation was retained. After an osteo-dural decompression of the posterior fossa, post-operative MRI revealed an aqueductal stenosis with triventricular hydrocephalus. An endoscopic-third- ventriculostomy showed an idiopathic stenosis of the right foramen of Monro. Residual symptoms and persistence of biventricular hydrocephalus justified a ventriculo-peritoneal shunt. Aqueductal and foramina of Monro stenosis can mimick a Chiari I malformation.

[Spontaneous cerebrospinal fluid rhinorrhea associated with long-standing overt ventriculomegaly in adults (LOVA)].

OBJECTIVE: Spontaneous cerebrospinal fluid rhinorrhea associated with aqueductal stenosis is rare. CSF diversion is reported to be a failure in the majority of cases. The combination of the repair of the skull base and CSF diversion is reported to be successful. We describe a case successfully treated by intradural repair with ventricular drainage followed by endoscopic third ventriculostomy. CLINICAL PRESENTATION: A 28-year-old woman presented with rhinorrhea, and occasional attacks of headache, vomiting, and unconsciousness for two years. She had been diagnosed as arrested hydrocephalus for 10 years. Magnetic resonance imaging revealed triventriculomegaly with ballooning of the floor of the third ventricle, tonsilar herniation, right anterior horn herniation into the cribriform plate, and bilateral temporal lobe herniation into the temporal base. INTERVENTION: A ventricular drain was inserted followed by dissection of the herniated brain and repair of the enlarged cribriform foramen with periosteal flap. Make sure that the bacterial culture negative, endoscopic third ventriculostomy has been performed. There is no recurrence of hydrocephalus and rhinorrhea for two years. CONCLUSION: Direct communication between the lateral ventricle and the nasal/paranasal sinus is a rare complication of aqueductal stenosis and LOVA. Surgical repair of the skull base followed by cerebrospinal fluid diversion with endoscopic third ventriculostomy was a safe and reliable method.

Diagnosis and Surgical Management of Neonatal Hydrocephalus.

Neonatal hydrocephalus represents an important pathological condition with significant impact on medical care and neurocognitive development. This condition requires early recognition, appropriate medical and surgical management, and long-term surveillance by clinicians and pediatric neurosurgeons. Common etiologies of neonatal and infant hydrocephalus include intraventricular hemorrhage related to prematurity with subsequent post-hemorrhagic hydrocephalus, myelomeningocele, and obstructive hydrocephalus due to aqueductal stenosis. Clinical markers of elevated intracranial pressure include rapid increases in head circumference across percentiles, elevation and firmness of the anterior fontanelle, splitting or splaying of cranial sutures, upgaze palsy, lethargy, frequent emesis, or episodic bradycardia (unrelated to other comorbidities). Complementing these clinical markers, imaging modalities used for the diagnosis of neonatal hydrocephalus include head ultrasonography, brain magnetic resonance imaging, and head computed tomography in urgent or emergent situations. Following diagnosis, temporizing measures may be employed prior to definitive treatment and include ventricular access device or ventriculo-subgaleal shunt insertion. Definitive surgical management involves permanent cerebrospinal fluid (CSF) diversion via CSF shunt insertion, or endoscopic third ventriculostomy with or without choroid plexus cauterization. Surgical decision-making and approaches vary based on patient age, hydrocephalus etiology, neuroanatomy, imaging findings, and medical comorbidities. Indications, surgical techniques, and clinical outcomes of these procedures continue to evolve and elicit significant attention in the research environment. In this review we describe the epidemiology, pathophysiology, clinical markers, imaging findings, early management, definitive surgical management, and clinical outcomes of pediatric patients with neonatal hydrocephalus.

Endoscopic third ventriculostomy for hydrocephalus: a review of indications, outcomes, and complications.

Endoscopic third ventriculostomy (ETV) has been in vogue for the past two decades, as a tool in the armamentarium of the neurosurgeon, for the management of hydrocephalus. Its utility has been proven consistently in congenital / acquired aqueductal stenosis, although the outcomes in communicating hydrocephalus as well as hydrocephalus secondary to other etiologies have not been as impressive. It is a relatively safe procedure with the appropriate selection of patients with a low rate of permanent morbidity. This review aims to define the current indications, management outcomes, and complications of ETV.

Common Trajectories for Freehand Frontal Ventriculostomy: A Systematic Review.

BACKGROUND: Freehand ventriculostomy is one of the most commonly performed neurosurgical procedures. While a variety of approaches have been described, frontal via Kocher's point is the most common. Multiple trajectories have been described, but no consensus exists as to the most efficacious. Our objective was to assess the literature regarding trajectories for frontal ventriculostomy and their associated success rates and complications. METHODS: We performed a systematic review of the literature, querying the PubMed/MEDLINE database with the search term "(EVD OR extra-ventricular drain OR ventriculostomy OR external ventricular drain) AND (hand OR freehand OR bedside)" and reported the characteristics and findings of both simulation and clinical studies according to trajectory and catheter position. Final catheter tip position was graded on the Kakarla scale. RESULTS: A total of 198 abstracts were screened; 40 full papers were assessed. Sixteen were included, 11 of which were clinical studies and 5 of which were simulation studies. Six studies coronally targeted the ipsilateral medial epicanthus (IMC), 4 utilized an orthogonal trajectory (P), and 1 targeted the naison (N). Ideal placement (Kakarla grade 1) was achieved in 954 of 1391 (68.58%) procedures when the IMC was targeted versus 243 of 354 (70.43%) when P was targeted. Potentially harmful (Kakarla grade 3) placement was observed in 142 of 1391 (10.21%) procedures when the IMC was targeted and 20 of 345 (5.80%) when P was targeted. All 5 simulation studies found the IMC target to be inferior. CONCLUSIONS: The IMC is the most prevalent trajectory for frontal ventriculostomy but no target is demonstrably superior. More robust clinical research is required to determine the optimal trajectory.