Long-term outcomes for children with an incidentally discovered Chiari malformation type 1: what is the clinical significance?

OBJECTIVES: Chiari malformation type 1 (CM1) is an increasingly common incidental finding on magnetic resonance imaging (MRI). The proportion of children with an incidentally discovered CM1 who upon further evaluation require operative intervention for previously unrecognized signs and symptoms of neurological compromise or significant radiographic findings (syringomyelia) is unclear. An extensive long-term single-institution patient series was evaluated to better clarify the likelihood of surgery in patients who present with an incidentally discovered CM1. METHODS: This study was conducted using prospective data for patients up to 18 years old that were evaluated for a CM1 at a large tertiary pediatric neurosurgery clinic between February 2009 and June 2019. Patients were excluded if they did not have an incidentally discovered CM1 and at least 12 months of clinical follow-up. RESULTS: A total of 218 consecutive patients were included in this study. The mean age at the initial neurosurgical evaluation was 6.5 years (range 5 months to 18.4 years), and the mean duration of clinical follow-up was 40.6 months (range 12 to 114 months). Initial MR imaging was most commonly obtained for the evaluation of seizures (15.1%), nonspecific headaches (not occipital or tussive) (14.7%), trauma (9.6%), and developmental delay (7.8%). Of the patients studied that eventually required surgery, we identified two groups: those operated before 6 months since presentation and those operated after 6 months. A total of 36 patients (16.5%) underwent a decompression with 22 patients (61.1%) receiving surgery within 6 months and the remaining 14 patients (38.9%) beyond 6 months. Patients undergoing early surgery (10.1%) initially presented with a significant syrinx or were noted to have an occult neurological dysfunction, whereas a smaller subset of patients (6.4%) eventually required surgery over time due to the development of new symptoms or a de novo syrinx. Only the presence of syringomyelia was statistically significant for the need of a surgical intervention, while age, sex and degree of tonsillar herniation were not. CONCLUSION: Evaluation of a large group of patients with an incidentally discovered Chiari malformation demonstrated that most patients may be managed conservatively, especially in the absence of syringomyelia. However, there is a subset of patients who will go on to develop a de novo syrinx or neurological symptoms that are new or progressive during follow-up, which should be evaluated by imaging of the brain and spinal cord. The presence of syringomyelia was associated with need for early surgical intervention. However, for patients without syringomyelia, surgical intervention is uncommon but may be delayed up to several years after presentation; therefore, long-term clinical follow-up is recommended.

Long-term outcomes of posterior fossa decompression for Chiari malformation type 1: which patients are most prone to failure?

PURPOSE: The role of an osseous-only posterior fossa decompression (PFD) for Chiari malformation type 1 (CM1) remains controversial. We reviewed long-term outcomes for patients with CM1 undergoing a PFD to evaluate if there was any difference for failure when compared to patients undergoing a PFD with duraplasty (PFDD). METHODS: Consecutive patients surgically treated at a single tertiary pediatric neurosurgery clinic over a 25-year period with at least 5 years of follow-up were evaluated. PFD patients were compared to those that initially received a PFDD. Demographics, surgical indications, surgical approach, outcomes, and complications were reviewed. RESULTS: A total of 60 patients were included in this study of which 25 (41.67%) underwent PFD and 35 (58.33%) underwent PFDD. Mean age at surgery was 7.41 years (range 0.4 to 18 years) with a mean follow-up of 8.23 years (range 5 to 21 years). Those that received a PFD had a lower rate of radiographic syrinx improvement (p = 0.03), especially in the setting of holocord syringes. Failure rate was significantly higher in the PFD group (20% vs 2.90%, p = 0.03). However, complications were significantly higher in the PFDD group (17.14% vs 4.0%, p = 0.04). CONCLUSIONS: PFD provides a safe treatment option with similar clinical improvements and lower post-operative complication rate compared to PFDD, albeit at the cost of greater chance of reoperation, especially in the setting of a holocord syrinx. Patients with a holocord syrinx should be considered for a PFDD as their initial procedure.

Endoscopic management of pineal cyst-associated aqueductal stenosis.

OBJECT: The purpose of this study was to evaluate whether endoscopic third ventriculostomy (ETV) and endoscopic cyst fenestration are effective minimally invasive alternatives to a craniotomy with cyst resection for the treatment of symptomatic pineal cyst-associated aqueductal stenosis. METHODS: Sixteen patients with symptomatic pineal cysts were operatively managed endoscopically and these cases were retrospectively reviewed. There were 12 females and 4 males. The median age at the time of surgery was 31 years (range 3 to 62 years). RESULTS: All patients presented with symptoms and imaging consistent with elevated intracranial pressure. The median maximum cyst diameter was 15 mm (range 10 mm to 27 mm). In all cases, there was mass effect on the tectum that resulted in effacement of the cerebral aqueduct and ventriculomegaly was present in 38% of cases. ETV was performed in 15 patients. Cyst fenestration was performed in 2 patients, one of which also had an ETV. Resolution of symptoms was achieved in 81% of patients with a median follow-up of 13 months. CONCLUSION: This study showed that ETV is effective for symptomatic pineal cyst-associated aqueductal stenosis. Patients can be symptomatic without overt ventriculomegaly and normal ventricular volume does not preclude safe endoscopic management. Endoscopic cyst fenestration is recommended if a Perinaud syndrome is present or if ETV is not feasible.

Multicenter comparison of Chiari malformation type I presentation in children versus adults.

OBJECTIVE: Treatment for Chiari malformation type I (CM-I) often includes surgical intervention in both pediatric and adult patients. The authors sought to investigate fundamental differences between these populations by analyzing data from pediatric and adult patients who required CM-I decompression. METHODS: To better understand the presentation and surgical outcomes of both groups of patients, retrospective data from 170 adults and 153 pediatric patients (2000-2019) at six institutions were analyzed. RESULTS: The adult CM-I patient population requiring surgical intervention had a greater proportion of female patients than the pediatric population (p < 0.0001). Radiographic findings at initial clinical presentation showed a significantly greater incidence of syringomyelia (p < 0.0001) and scoliosis (p < 0.0001) in pediatric patients compared with adult patients with CM-I. However, presenting signs and symptoms such as headaches (p < 0.0001), ocular findings (p = 0.0147), and bulbar symptoms (p = 0.0057) were more common in the adult group. After suboccipital decompression procedures, 94.4% of pediatric patients reported symptomatic relief compared with 75% of adults with CM-I (p < 0.0001). CONCLUSIONS: Here, the authors present the first retrospective evaluation comparing adult and pediatric patients who underwent CM-I decompression. Their analysis reveals that pediatric and adult patients significantly differ in terms of demographics, radiographic findings, presentation of symptoms, surgical indications, and outcomes. These findings may indicate different clinical conditions or a distinct progression of the natural history of this complex disease process within each population, which will require prospective studies to better elucidate.

The safety of the intraoperative sacrifice of the deep cerebral veins.

BACKGROUND: The effect of surgically ligating the deep cerebral veins is often thought to be of significant risk. That concern and the paucity of information on surgery of the deep venous system confound surgical decision making when operations involve manipulation of the deep cerebral veins. DISCUSSION: The authors review the human and animal literature on the selective sacrifice of the deep cerebral veins. Robust experimental studies and limited clinical experience indicate that occlusion of one or several deep cerebral veins is generally safe.

Facilitation of Pediatric Posterior Fossa Vascular Malformation Resection Using Virtual Reality Platform: 2-Dimensional Operative Video.

Pediatric posterior fossa arteriovenous malformations (AVMs) are rare entities that pose significant cumulative lifetime risk of rupture and require treatment. Microsurgical resection remains a good option for definitively treating posterior fossa AVMs in one setting. The drawback of endovascular embolization is the lower rates of nidus obliteration. Although stereotactic radiosurgery is a safe alternative, it takes several years to achieve the treatment goal all the while predisposing the patient to the risk of AVM rupture.1,2 Accurate localization and visualization remain challenging for microsurgical treatment of posterior fossa AVMs.3-5 Small size of a nidus, prone position, and proximity to eloquent areas make these lesions particularly difficult to localize and resect. We present the operative case of a 6-year-old boy with a small, ruptured posterior fossa AVM. After undergoing hematoma evacuation, the patient underwent microsurgical resection of a small right vermian AVM assisted by the virtual reality platform, Surgical Theater (Gates Mills, OH). Our video demonstrates the utility of a virtual augmented reality platform for addressing the challenges posed by a small posterior fossa AVM with respect to the need for precise three-dimensional localization of small lesions. The patient consented to the procedure. The participants and any identifiable individuals consented to publication of his/her image.

Native Ureter Ventriculo-Ureteral Shunt Placement for Management of Refractory Hydrocephalus in a Child With a History of Renal Transplant: Case Report and Technical Note.

This report describes the case of a 5-year-old male with intractable hydrocephalus secondary to neonatal intraventricular hemorrhage who was ultimately managed with the placement of a ventriculo-ureteral (VU) shunt. He had previously failed numerous attempts at cerebrospinal fluid shunting, choroid plexus cauterization, and endoscopic third ventriculostomy. The patient had a history of end stage renal disease, and had previously undergone renal transplant. In an operation that involved Neurosurgeons, Pediatric Urologists, and Transplant surgeons, a Gibson incision was used to avoid the patient's multiple intra-abdominal adhesions, and his nonfunctioning renal unit was used to implant a VU shunt without early or late complications.

Innovative approach to the difficult ventricular shunt using pleural access device for maintenance drainage: case report.

Patients with complex medical problems and multiple failed ventricular shunts require continued innovation for hydrocephalus management. The authors report the case of a 4-year-old boy with refractory hydrocephalus and secondary reduced ability to absorb CSF in both the pleural and peritoneal cavities following renal transplantation. A novel management approach was devised with split shunting to pleural and peritoneal targets as well as prophylactic pleural port placement to provide a method for minimally invasive thoracentesis should symptomatic pleural effusions develop. Fluid was successfully aspirated via the pleural port with relief of symptoms over a period of 16 months without complication. The authors demonstrate that a previously undescribed approach to distal shunting can prevent neurological sequelae of shunt failure and permit noninvasive maintenance drainage for patients in whom symptomatic pleural effusion is a recurrent complication.

Delayed toxicity from gamma knife radiosurgery to lesions in and adjacent to the brainstem.

The aims of this study were to assess the incidence of, and risk factors for, delayed toxicity following gamma knife stereotactic radiosurgery (GKRS) to lesions in and adjacent to the brainstem. We retrospectively evaluated the delayed toxicity of GKRS following the treatment of 114 lesions in and adjacent to the brainstem in 107 patients. The median tumor volume was 6.2 cm(3) and the median dose to the tumor margin was 16Gy. The mean follow-up was 40 months. Thirteen patients (12%) demonstrated clinical evidence of delayed toxicity, with a median latency to the development of toxicity of 6 months. The actuarial incidence of toxicity at 1 year and 5 years was 10.2% and 13.8%. Larger tumor volume (p=0.02) and larger treatment volume (p=0.04) were associated with an increased incidence of delayed toxicity. Large lesions adjacent to the brainstem have a higher than previously suspected rate of delayed toxicity.

Completely intraosseous atretic meningocele.

Atretic meningoceles are infrequent congenital malformations resulting from the herniation of meninges through a skull defect. All prior reported cases have had a subcutaneous component with or without an underlying osseous defect. We report the unusual case of a completely intraosseous atretic meningocele.

Postoperative Gamma Knife surgery for benign meningiomas of the cranial base.

OBJECT: The standard treatment for meningiomas is complete resection, but the proximity of skull base meningiomas to important neurovascular structures makes complete excision of the lesion difficult or impossible. The authors analyzed the mid- and long-term results obtained in patients treated with postresection Gamma Knife surgery (GKS) for residual or recurrent benign meningiomas of the cranial base. METHODS: Thirty-six patients with residual or recurrent benign meningiomas of the skull base following one or more surgical procedures underwent GKS. There were 31 women and five men, ranging in age from 22 to 73 years. The median tumor volume was 4.1 ml (range 0.8-20 ml) and the median radiation dose to the tumor margin was 16 Gy (range 15-16 Gy). RESULTS: Patients were followed for a median of 81 months (range 30-141 months) after GKS. At the end of the follow-up period, overall neurological improvement was observed in 16 patients (44.4%), whereas the condition in 20 patients (55.6%) was unchanged. One patient suffered transient cerebral edema 6 months after GKS. Based on imaging documentation, a partial response was seen in five patients (13.9%), the disease remained stable in 30 patients (83.3%), and in one patient (2.8%) there was an increase in tumor size. The actuarial progression-free survival rate was 100% at 5 years and 94.7% at 10 years. CONCLUSIONS: Gamma Knife surgery was shown to be an excellent adjunct to resection because of its durable rate of tumor control and low toxicity. It should be initially considered along with surgery for the treatment of complex skull base meningiomas.

PIK3CA mutation in a mixed dysembryoplastic neuroepithelial tumor and rosette forming glioneuronal tumor, a case report and literature review.

BACKGROUND: Rosette forming glioneuronal tumors are rare, World Health Organization (WHO) grade I novel tumors frequently affecting the fourth ventricle or posterior fossa with typical neuronal pseudorosettes. RGNTs have been described as possessing additional histologic features of DNETs or pilocytic astrocytomas. Activating PIK3CA mutations have been identified as recurring genetic event in RGNTs. METHODS: We report a 35year old man who presented with binocular diplopia, headache, and was found to have a third ventricle tumor. Tumor pathology and oncogene evaluation were conducted. RESULTS: The tumor demonstrated histologic features consistent with mixed RGNT/DNET. Genetic studies revealed a PIK3CA mutation in exon 9 (E545K, C. 1633G>A) without IDH1, p53, 1p19q chromosomal co-deletion, or BRAF mutations. A literature search revealed six cases of PIK3CA mutations in RGNTs and seven cases of mixed RGNT/DNET. No cases of mixed RGNT/DNET with a PIK3CA mutation have been described. CONCLUSION: This is the first documented case of an RGNT/DNET with an activating PIK3CA mutation. The presence of a PIK3CA mutation aids histologic classification in the setting of mixed histology, and may have implications for targeting the PI3K/AKT/mTOR pathway in this tumor type.

Epidural-cutaneous fistula in association with the Pott puffy tumor in an adolescent. Case report.

The Pott puffy tumor is a subperiosteal abscess associated with underlying osteomyelitis, most often of the frontal bone in conjunction with frontal sinusitis. Intracranial sequelae can include epidural abscess, subdural empyema, intraparenchymal abscess, meningitis, and dural venous thrombophlebitis, all with resultant neurological deterioration. Although once common, this entity has become rare since the introduction of antibiotic agents. The authors present an unusual case of a 14-year-old girl suffering from the Pott puffy tumor whose condition was further complicated by a draining epidural-cutaneous fistula and an epidural abscess.

Case report: pseudotail with dermal sinus tract and tethered cord.

A pseudotail is a very rare, dermal appendage arising from the lumbosacral region with an association with spinal dysraphism. We report a case of a pseudotail in a healthy newborn female with sonographic imaging of a tethered cord and dermal sinus tract with MRI and surgical correlation.

Use of a Minimally Invasive Retractor System for Retrieval of Intracranial Fragments in Wartime Trauma.

OBJECTIVE: Wartime penetrating brain injury can result in deep-seated parenchymal and intraventicular shrapnel, bullets, and bone. Large fragments pose a risk of secondary injury from migration, infection, and metal toxicity. It has been recommended that aggressive removal of fragments be avoided. The goal of this study is to report our technique of minimally invasive removal of select deep-seated fragments using a tubular retractor system. METHODS: A retrospective review of our database of service members presenting with penetrating traumatic brain injuries incurred during Operations Iraqi Freedom and Enduring Freedom and treated at the Walter Reed Army Medical Center and the National Naval Medical Center was performed. Six individuals were identified in which the Vycor ViewSite retractor system (Vycor Medical, Boca Raton, Florida, USA) was used to remove a ventricular or deep intraparenchymal fragment. All patients were male and ranged in age from 21 to 29 years. Fragment location included the foramen of Monro; the atrium of the right lateral ventricle; parasagittally within the right occipital lobe; the occipital horn of the right lateral ventricle; the deep white matter of the dominant temporal lobe; and within the posterior right temporal lobe deep to the junction of the transverse and sigmoid dural venous sinuses. Fragments included in-driven bone, shrapnel from improvised explosive devices, and bullets. RESULTS: In all cases the fragment was successfully removed. No patient had worsening of their neurologic condition following surgery. CONCLUSION: Deep parenchymal and intraventricular fragments can be safely removed using a tubular retractor system.

Posterior interhemispheric retrocallosal approach to pineal region and posterior fossa lesions in a pediatric population.

OBJECT: The purpose of this study was to evaluate the posterior interhemispheric retrocallosal approach (PIRA) for its safety and efficacy in the resection of pineal region and posterior fossa lesions in children. METHODS: Twenty-nine PIRAs were performed in 26 children between March 1997 and March 2009, and these cases were retrospectively reviewed. There were 15 girls and 11 boys in the series. The median age at the time of surgery was 7 years (range 7 months-17 years). Twenty-seven cases were treated for tumor, 1 for loculated hydrocephalus, and 1 for an aneurysm. RESULTS: Of the 27 cases treated for tumor, there were 20 (74%) gross-total resections, 5 (19%) subtotal resections, and 2 (7%) biopsies. One bridging vein was sacrificed in 6 cases and 2 bridging veins were divided in 1 case, whereas in 3 cases there was sacrifice of a single deep cerebral vein. No patient developed radiographic evidence of venous infarction. Approach-related complications were low, and included 2 cases of transient homonymous hemianopia. There were no surgery-related deaths. CONCLUSIONS: This approach allows for ample access to pineal region and posterior fossa lesions, with low postoperative morbidity.

Nondysraphic pediatric intramedullary spinal cord lipomas: report of 5 cases.

OBJECT: Intramedullary spinal cord lipomas not associated with dysraphism are infrequently reported. When present, they typically occur in children and have a predilection for the cervical and thoracic spinal cord. The authors review the presentation, treatment, and disease course in 5 pediatric patients, and compare the outcomes with previously reported cases. METHODS: With institutional review board approval, a retrospective chart review was undertaken at Children's Hospital Los Angeles. RESULTS: Four patients with intramedullary spinal cord lipomas and 1 patient with a lipoblastoma, none associated with dysraphism, were retrospectively reviewed. There were 2 boys and 3 girls ranging in age from 2 months to 4 years. Four patients underwent a laminectomy or laminoplasty with one or more subtotal resections. One patient initially underwent a decompressive laminoplasty without debulking. The median follow-up was 8 years (range 12 months-11 years). Two patients had regrowth of their lipoma, necessitating a second surgery in one patient and 3 debulking surgeries in the other. Postoperatively, 3 patients developed mild kyphosis, none significant enough to require orthopedic intervention. One patient underwent a stabilization procedure at the time of the initial laminectomy and tumor debulking. No patient received chemotherapy or radiation. At the most recent follow-up visit, patients demonstrated improved neurological function when compared with preoperative status. CONCLUSIONS: In addition to a decompressive laminectomy, debulking of the lipoma provides the best long-term neurological outcome. Gross-total excision is not warranted and usually is not possible. Long-term follow-up is needed, and repeat debulking of the lipoma is indicated if there is an increase in tumor size due to hyperplasia of residual adipocytes, when tumor growth is associated with neurological deterioration.

Aggressive variant of a papillary glioneuronal tumor. Report of 2 cases.

Papillary glioneuronal tumors are a newly recognized type of brain neoplasm characterized by prominent pseudopapillary structures and glioneuronal elements. All prior cases have shown that these tumors have an indolent course. The authors present 2 patients with an aggressive variant of the tumor. The first patient had dissemination of her tumor and the second had local spreading. Therefore, the authors conclude that papillary glioneuronal tumors do not always behave in a strictly benign fashion.