Management of Chiari I malformations: a paradigm in evolution.

PURPOSE: Despite decades of experience and research, the etiology and management of Chiari I malformations (CM-I) continue to raise more questions than answers. Controversy abounds in every aspect of management, including the indications, timing, and type of surgery, as well as clinical and radiographic outcomes. This review aims to outline past experiences, consolidate current evidence, and recommend directions for the future management of the Chiari I malformation. METHODS: A review of recent literature on the management of CM-I in pediatric patients is presented, along with our experience in managing 1073 patients who were diagnosed with CM-I over the past two decades (1998-2018) at Children's National Medical Center (CNMC) in Washington DC. RESULTS: The general trend reveals an increase in the diagnosis of CM-I at younger ages with a significant proportion of these being incidental findings (0.5-3.6%) in asymptomatic patients as well as a rise in the number of patients undergoing Chiari posterior fossa decompression surgery (PFD). The type of surgical intervention varies widely. At our institution, 104 (37%) Chiari surgeries were bone-only PFD with/without outer leaf durectomy, whereas 177 (63%) were PFD with duraplasty. We did not find a significant difference in outcomes between the PFD and PFDD groups (p = 0.59). An analysis of failures revealed a significant difference between patients who underwent tonsillar coagulation versus those whose tonsils were not manipulated (p = 0.02). CONCLUSION: While the optimal surgical intervention continues to remain elusive, there is a shift away from intradural techniques in favor of a simple, extradural approach (including dural delamination) in pediatric patients due to high rates of clinical and radiographic success, along with a lower complication rate. The efficacy, safety, and necessity of tonsillar manipulation continue to be heavily contested, as evidence increasingly supports the efficacy and safety of less tonsillar manipulation, including our own experience.

CNS germ cell tumor (CNSGCT) of childhood: presentation and delayed diagnosis.

OBJECTIVE: To describe the relationship between symptomatology and time to diagnosis of an institutional series of patients with CNS germ cell tumor (CNSGCT) over a 16-year period. METHODS: Thirty consecutive patients newly diagnosed with CNSGCT (mean age 10.9 years; range 6 to 17 years; 70% boys) were evaluated at our institution between 1990 and 2006. RESULTS: Duration of symptoms prior to diagnosis ranged from 5 days to 3 years (mean 8.4 months). Tumor location included pineal (14), suprasellar (8), pineal/suprasellar (3), pineal/thalamic (4), and basal ganglionic/thalamic (3). Five patients had disseminated disease at the time of diagnosis. Features including headache, nausea, vomiting, and visual changes led to earlier diagnosis. Symptoms including movement disorders, enuresis, anorexia, and psychiatric complaints delayed diagnosis in 9 of 30 patients, diagnosed 7 months to 3 years (mean 22.3 months) from symptom onset. In 7 of 9 patients with delayed diagnosis, enuresis was present. Seventeen of 30 patients had signs of endocrine dysfunction at presentation that included diabetes insipidus (4), hypothyroidism (8), and growth hormone deficiency (4). Ophthalmologic findings of decreased visual acuity, visual field deficits, or ocular abnormalities were present in 13 patients. Duration of symptoms did not correlate with tumor subtype or event-free survival. In three patients with basal ganglionic/temporal lobe, thalamic, or pineal/suprasellar signal abnormalities on MRI, neuroradiographic diagnosis was difficult. CONCLUSIONS: Diagnosis of CNS germ cell tumor is often delayed, and presentation may include movement disorders or mimic psychiatric disease. MRI interpretation can be challenging and may require serum/CSF markers and biopsy for diagnosis.

Functional magnetic resonance imaging in pediatrics.

Functional magnetic resonance imaging (fMRI) allows non-invasive assessment of human brain function in vivo by detecting blood flow differences. In this review, we want to illustrate the background and different aspects of performing functional magnetic resonance imaging (fMRI) in the pediatric age group. An overview over current and future applications of fMRI will be given, and typical problems, pitfalls, and benefits of doing fMRI in the pediatric age group are discussed. We conclude that fMRI can successfully be applied in children and holds great promise for both research and clinical purposes.

Endoscopic access to the infratemporal fossa and skull base: a cadaveric study.

OBJECTIVES: To demonstrate that the regions of the infratemporal fossa and skull base at the level of the foramen ovale can be visualized endoscopically and that structures can be manipulated within these regions using endoscopic instruments. METHODS: Cadaveric dissection of 3 human cadavers using an endoscopic optical dissector. In all, 6 endoscopic infratemporal fossa and skull base approaches were performed. SETTING: Human temporal bone laboratory. RESULTS: A Gillies incision was coupled with a lateral brow incision, and then subperiosteal planes were developed. Endoscopic visualization and instrumentation was then performed. The infratemporal fossa was readily identified. The skull base at the level of the foramen ovale and the branches of the third division of the trigeminal nerve were seen distinctly. A probe was placed with ease within the foramen ovale itself. CONCLUSIONS: Endoscopic access to the infratemporal fossa is readily accomplished, with excellent visualization and instrumentation ability. This novel technique provides access to this remote region for evaluation, possible biopsy, and potential treatment of infratemporal fossa lesions.

True fungal mycotic aneurysm of the basilar artery: a clinical and surgical dilemma.

Mycotic aneurysms of the intracranial circulation of true fungal etiology are extremely rare and are associated with a very high mortality. We report a case of a fatal aneurysm of the basilar artery secondary to Scedosporium apiospermum infection. The medical and surgical treatments are presented to demonstrate the difficulties associated with these lesions.

The rationale for glutamate antagonists in the treatment of traumatic brain injury.

The recent development of potent antagonists for the most widespread neurotransmitter in the mammalian brain has opened up possibilities for many forms of therapy. The excitotoxic hypothesis implicates excessive release of excitatory amino acids (EAAs) as an important cause of brain damage, especially in acute ischemia, and chronic neurodegeneration. Focal ischemic damage and diffuse axonal injury are the major causes of brain damage after traumatic human brain injury. Evidence from animal models has shown that excitatory amino acid-induced events maybe responsible for a proportion of the posttraumatic sequelae and that these effects can be blocked by EAA antagonists. This evidence is reviewed, and the implications for human pathophysiology and treatment are discussed.

Coagulopathy with the use of hetastarch in the treatment of vasospasm.

The use of colloid agents to achieve hypervolemia in the prevention and treatment of postsubarachnoid hemorrhage (post-SAH) vasospasm is included in the standard of care at many institutions. Risk profiles are necessary to ensure appropriate use of these agents. In a series of 85 patients with recent aneurysmal SAH, 26 developed clinical symptoms of vasospasm. Fourteen of the 26 were treated with hetastarch for volume expansion while the other 12 received plasma protein fraction (PPF). Clinically significant bleeding pathologies were noted in six patients who received hetastarch as a continuous intravenous infusion. Hetastarch increased partial thromboplastin time from a mean of 23.9 seconds to a mean of 33.1 seconds (p < 0.001) in all patients who received infusions of this agent, while no effect was noted in the 12 patients who received PPF infusions. No other coagulation parameters were altered. This study shows an increase in coagulopathy with the use of hetastarch as compared with the use of PPF for the treatment of postaneurysmal vasospasm.

Symptomatic lumbar stenosis following fusion using sublaminar hooks. Case report.

A case of postfusion lumbar stenosis caused by the presence of sublaminar hooks is described. The patient was a 52-year-old man who 11 years previously had undergone lumbar fusion with Harrington rod instrumentation for a traumatic L-2 vertebral body fracture. Postoperatively, he developed progressive low-back pain, neurogenic claudication, and significant lower-extremity weakness and atrophy. Upon radiological examination, he was found to have high-grade lumbar stenosis at the level of the caudal sublaminar hooks. The instrumentation was removed and the area of radiological stenosis decompressed. Clinically, both the patient's pain and motor deficits resolved and, on postoperative imaging, the stenosis was relieved. Thus, despite other areas of persisting pathology, it is concluded that the stenosis occurring at the level of the caudal sublaminar hooks contributed to the patient's symptoms. Although not a common cause of postfusion stenosis, the presence of instrumentation in the proximity of neural elements must be considered as an etiology for neurological dysfunction.

Atlantooccipital subluxation in a neonate with Down's syndrome. Case report and review of the literature.

Atlantooccipital subluxation (AOS) occurs in up to 63% of patients with Down's syndrome. However, presenting symptoms and the age at which preoperative screening becomes necessary have not been clearly delineated. Recently, a 16-day-old female with Down's syndrome and AOS presented to our institution. Following patent ductus arteriosus ligation, her neurological examination revealed trace movement, few spontaneous respirations, and left lower extremity clonus. Cervical spine radiographs revealed significant AOS. She was reduced and underwent a fusion from the occiput to C2. She gradually regained full strength and sensation. This case is the youngest example of AOS related to Down's syndrome described. It emphasizes the need for preoperative screening of all patients with Down's syndrome.

Interstitial chemotherapy of the 9L gliosarcoma: controlled release polymers for drug delivery in the brain.

The administration of drugs directly into the central nervous system using polymers as drug carriers may improve the treatment of malignant brain tumors. In this study, the effect of the interstitial, localized delivery of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) incorporated into controlled release polymers implanted adjacent to the 9L gliosarcoma was assessed in s.c. and intracranial (i.c.) models. In the s.c. experiment, the 9L gliosarcoma was implanted in the flank of rats and subsequently treated with BCNU either (a) delivered in controlled release polymers inserted adjacent to the tumor or (b) administered systemically by i.p. injections or by controlled release polymers inserted at a site distant from the tumor. The interstitial release of BCNU adjacent to the tumor in the flank resulted in a significant tumor growth delay of 16.3 days, as compared to a growth delay of 9.3 and 11.2 days obtained with the systemic administration of BCNU. In the i.c. experiment, the 9L gliosarcoma was implanted in the brain of Fischer 344 rats and treated either (a) with controlled release polymers containing BCNU inserted into the brain or (b) with the systemic i.p. administration of BCNU. The interstitial release of BCNU in the brain resulted in a significant 5.4- to 7.3-fold increased survival, compared with a 2.4-fold increased survival after the systemic administration of the same dose of BCNU. The two groups with i.c. tumors treated interstitially had 17 and 42% cures, but no long-term cures were obtained in the group treated with systemic therapy. The localized, controlled delivery of chemotherapeutic agents in the s.c. tissues and in the brain via polymeric carriers may be more effective than standard systemic chemotherapy. This approach could be used to deliver a wide variety of agents into the central nervous system to treat diverse neuropathological conditions which remain refractory to systemic therapy.