Meningomyelocele Reconstruction: Comparison of Repair Methods via Systematic Review.

PURPOSE: The purpose of this article was to appraise the various methods of reconstruction for meningomyelocele (MMC) defects. METHODS: A systematic review of the literature was performed to evaluate all reconstructions for MMC. The method of reconstruction was categorized by: primary closure with and without fascial flaps, random pattern flaps, VY advancement flaps (VY), perforator flaps, and myocutaneous flaps. Perforator flaps were subsequently subcategorized based on the type of flap. RESULTS: Upon systematic review, 567 articles were screened with 104 articles assessed for eligibility. Twenty-nine articles were further reviewed and included for qualitative synthesis. Two hundred seventy patients underwent MMC repair. The lowest rates of major wound complications (MWC) were associated with myocutaneous and random pattern flaps. A majority of MWC was in the lumbrosacral/sacral region (87.5% of MWC). In this region, random patterns and perforator flaps demonstrated the lowest rate of MWC (4.5, 8.1%). CONCLUSIONS: Plastic surgery consultation should be strongly considered for MMC with defects in the lumbosacral/sacral region. Perforator flaps are excellent options for the reconstruction of these defects.

Preoperative Frontal and Parietal Bone Thickness Assessment to Predict Blood Loss and Transfusion During Extended Suturectomy for Isolated Sagittal Craniosynostosis.

OBJECTIVE: To predict the morbidity of sagittal suturectomy using preoperative computer tomographic measurement of frontal and parietal bone thickness in osteotomy sites. DESIGN: Retrospective analysis. SETTING: Tertiary children's hospital. PATIENTS: Fifty infants with nonsyndromic, isolated sagittal craniosynostosis who underwent extended sagittal suturectomy from 2015-2022. METHODS: Mean thickness of the frontal and parietal bone in regions of osteotomies were determined for each patient from preoperative CT images obtained within 30 days prior to suturectomy. The relationship between bone thickness (mm) and estimated blood loss (mL) was evaluated using Spearman's correlation and a multivariable model that adjusted for patient weight and surgery duration. The association between bone thickness and perioperative blood transfusion was evaluated using a multivariable logistic model controlling for patient weight and surgery duration. MAIN OUTCOME MEASURES: Estimated blood loss, perioperative blood transfusion. RESULTS: Frontal and parietal bone thickness in the region of osteotomies were positively correlated with estimated blood loss (p < 0.01). After adjusting for patient weight and duration of operation, both parietal and frontal bone thickness were associated with intraoperative blood loss (R2 = 0.292, p = 0.002 and R2 = 0.216, p = 0.026). Thicker frontal and parietal bone in the line of osteotomies resulted in significantly higher odds of blood transfusion. Bone thickness in the line of parietal osteotomies was 76% accurate at identifying patients who would require blood transfusion (p = 0.004). CONCLUSIONS: Frontal and parietal bone thickness in the line of osteotomies is associated with blood loss and perioperative blood transfusion for sagittal suturectomy operations.

De Novo Variants Disrupting the HX Repeat Motif of ATN1 Cause a Recognizable Non-Progressive Neurocognitive Syndrome.

Polyglutamine expansions in the transcriptional co-repressor Atrophin-1, encoded by ATN1, cause the neurodegenerative condition dentatorubral-pallidoluysian atrophy (DRPLA) via a proposed novel toxic gain of function. We present detailed phenotypic information on eight unrelated individuals who have de novo missense and insertion variants within a conserved 16-amino-acid "HX repeat" motif of ATN1. Each of the affected individuals has severe cognitive impairment and hypotonia, a recognizable facial gestalt, and variable congenital anomalies. However, they lack the progressive symptoms typical of DRPLA neurodegeneration. To distinguish this subset of affected individuals from the DRPLA diagnosis, we suggest using the term CHEDDA (congenital hypotonia, epilepsy, developmental delay, digit abnormalities) to classify the condition. CHEDDA-related variants alter the particular structural features of the HX repeat motif, suggesting that CHEDDA results from perturbation of the structural and functional integrity of the HX repeat. We found several non-homologous human genes containing similar motifs of eight to 10 HX repeat sequences, including RERE, where disruptive variants in this motif have also been linked to a separate condition that causes neurocognitive and congenital anomalies. These findings suggest that perturbation of the HX motif might explain other Mendelian human conditions.

Pediatric intracranial arterial injuries by penetrating gunshot wounds: an institutional experience.

PURPOSE: Pediatric intracranial injuries due to penetrating gunshot wounds are a rare entity that is often fatal. A subset of patients may experience an intracerebral arterial injury; however, literature on the pediatric population is limited. This study analyzes a large institution's experience with pediatric head gunshot wounds and intracranial arterial injuries. METHODS: All pediatric patients ≤ 18 years of age who presented to our institution with a penetrating gunshot wound from 2008 to 2018 were retrospectively analyzed. RESULTS: Thirty-seven patients presented with an intracerebral penetrating gunshot injury. There were 18 deaths (49%) in the cohort. A total of 20 patients (54%) had vascular imaging. Of the remaining 17 patients with no vascular imaging, 13 (35%) died before any vascular studies were obtained. Four (20%) of the 20 patients with vascular imaging experienced an intracerebral arterial injury. Three of these 4 patients died before treatment could be administered. One patient with a firearm injury underwent embolization of a distal middle cerebral artery pseudoaneurysm and was discharged home with a Glasgow Outcome Scale score of 5 on follow-up. CONCLUSION: Pediatric patients with penetrating intracranial gunshot wounds often die before vascular imaging can be obtained.

Accessory Cranial Suture Leading to Abnormal Head Shape.

ABSTRACT: Accessory cranial sutures have been described in the literature and are most commonly associated with the parietal bone. These sutures are typically identified incidentally and there have been no reported cases of accessory cranial sutures leading to abnormal head shape.The authors present the case of a 3-month-old patient with multiple congenital anomalies and an accessory parietal suture leading to abnormal head shape. The patient was successfully treated with cranial orthotic therapy. To our knowledge, this is the first reported case of an accessory cranial suture leading to abnormal head shape.

Outcomes of Titanium Mesh Cranioplasty in Pediatric Patients.

PURPOSE: Cranial defects in children have been repaired with various materials ranging from autologous bone to synthetic materials. There is little published literature on the outcomes of titanium mesh cranioplasty (TMC) in calvarial reconstruction in the pediatric population. This study evaluates a pediatric cohort who underwent calvarial defect reconstruction with titanium mesh and assesses the efficacy and outcomes of TMC. METHODS: An Institutional Review Board approved retrospective review of patients ≤18 years of age who underwent cranioplasty from 1999 to 2014 at 2 centers was performed. The cohort undergoing TMC was studied. RESULTS: A total of 159 cranioplasties were performed. Autologous reconstruction included 84 bone flap replacements and 36 split calvarial bone graft reconstructions. Six patients underwent PEEK implant reconstruction. Titanium mesh cranioplasty was performed on 33 patients. Two patients underwent 2 separate cranioplasties. The median age of patients was 6 years (19 months to 18 years). The most common underlying etiologies were congenital syndromes/craniosynostosis (13 patients), and trauma (11). The majority of patients had prior cranial surgeries (85%). Various types of titanium mesh were used with sizes ranging from 2×3 cm to 19×20 cm, with some patients requiring distinct areas of defect reconstruction. Perioperative complications were noted in 2 patients that subsequently improved. Two patients had late soft tissue problems with complications of wound infections requiring resection of a portion of the mesh. Patients were followed an average of 4 years (range 13 days to 6.8 years), with 2 patients lost to follow-up. Overall, all patients with follow-up achieved a cranial contour with good symmetry to the unaffected side, as well as effective protection to the brain. CONCLUSIONS: Titanium mesh cranioplasty is an effective option for correcting pediatric cranial defects when autologous bone availability is limited and soft tissue coverage allows placement of an implant. The interim outcome for these patients is favorable with few complications and no evidence of growth restriction in the authors' series. Follow-up will be ongoing for these patients.

Tranexamic Acid Reduces Blood Loss in Craniosynostosis Surgery.

METHODS: The authors retrospectively reviewed 79 patients with craniosynostosis who underwent either bifrontal or biparietal-occipital calvarial vault remodeling before institution of tranexamic acid (TXA) administration (non-TXA group) and 35 patients after institution of TXA administration (TXA group). The patients were analyzed in 2 groups: all open calvarial vault remodeling patients (anterior and posterior) as a whole, and anterior vaults only as a subset analysis. Primary outcomes accessed were: total intraoperative blood transfused, postoperative blood transfused, and estimated blood loss (EBL). Secondary outcomes evaluated were length of stay in the pediatric intensive care unit and hospital length of stay. RESULTS: When comparing all open calvarial vault remodeling patients, patients who received TXA required significantly less total blood transfusion during their operation (264 cc TXA group versus 428 cc non-TXA, P < 0.0001). Patients who received TXA required no blood transfusions postoperatively, compared with the non-TXA group, in which 45% of patients required postoperative blood transfusion. Weight-based EBL was also significantly lower in those patients receiving TXA (25 cc/kg in the TXA group versus 34 cc/kg in the non-TXA group [P = 0.0143]). All patients required transfusion intraoperatively. Pediatric intensive care unit length of stay was shorter in the TXA group, but there was no significant difference in total hospital length of stay. These findings also reached statistical significance when comparing only the anterior vault patients. CONCLUSION: Intraoperative TXA administration has a correlation with reduced blood transfusion requirements, as well as EBL, in patients undergoing open calvarial vault remodeling. There were no adverse events related to TXA administration.

Long term outcome after surgical treatment for hypothalamic hamartoma.

PURPOSE: To determine long-term outcome for seizure control and clinical predictors for seizure freedom in patients undergoing surgical treatment for epilepsy associated with hypothalamic hamartoma (HH). METHODS: 155 patients underwent surgical treatment for HHs and treatment-resistant epilepsy at one center (Barrow Neurological Institute at St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA) between February 2003 and June 2010. Data collection included medical record review and direct follow-up interviews to determine seizure outcome. Statistical analysis included descriptive summaries of patient characteristics and time-to-event analysis for seizure freedom. RESULTS: Long-term survival with follow-up of at least five years since first surgical treatment was available for 108 patients (69.7% of the treatment cohort). The surgical approach for first HH intervention consisted of transventricular endoscopic resection (n = 57; 52.8%), transcallosal interforniceal resection (n = 35; 32.4%), pterional resection (n = 7; 6.5%), and gamma knife radiosurgery (n = 9; 8.3%). Multiple surgical procedures were required for 39 patients (36.1%). There were 10 known deaths from all causes in the treatment cohort (6.5%). Of these, one (0.6%) was related to immediate complications of HH surgery, three (1.9%) were attributed to Sudden Unexpected Death in Epileptic Persons (SUDEP), and one (0.6%) to complications of status epilepticus. For surviving patients with long-term follow-up, 55 (50.9%) were seizure-free for all seizure types. Univariable analysis showed that seizure-freedom was related to 1) absence of a pre-operative history for central precocious puberty (p = 0.01), and 2) higher percentage of HH lesion disconnection after surgery (p = 0.047). Kaplan-Meier survival analysis shows that long-term seizure outcome following HH surgery is comparable to short-term results. SUMMARY: These uncontrolled observational results show that long-term seizure control following HH surgical treatment is comparable to other forms of epilepsy surgery. Late relapse (at least one year after surgery) and SUDEP do occur, but in a relatively small number of treated patients. These results inform clinical practice and serve as a comparable benchmark for newer technologies for HH surgery, such as magnetic resonance imaging-guided laser interstitial thermal therapy, where long-term outcome results are not yet available.

Hydrogel Check-Valves for the Treatment of Hydrocephalic Fluid Retention with Wireless Fully-Passive Sensor for the Intracranial Pressure Measurement.

Hydrocephalus (HCP) is a neurological disease resulting from the disruption of the cerebrospinal fluid (CSF) drainage mechanism in the brain. Reliable draining of CSF is necessary to treat hydrocephalus. The current standard of care is an implantable shunt system. However, shunts have a high failure rate caused by mechanical malfunctions, obstructions, infection, blockage, breakage, and over or under drainage. Such shunt failures can be difficult to diagnose due to nonspecific systems and the lack of long-term implantable pressure sensors. Herein, we present the evaluation of a fully realized and passive implantable valve made of hydrogel to restore CSF draining operations within the cranium. The valves are designed to achieve a non-zero cracking pressure and no reverse flow leakage by using hydrogel swelling. The valves were evaluated in a realistic fluidic environment with ex vivo CSF and brain tissue. They display a successful operation across a range of conditions, with negligible reverse flow leakage. Additionally, a novel wireless pressure sensor was incorporated alongside the valve for in situ intracranial pressure measurement. The wireless pressure sensor successfully replicated standard measurements. Those evaluations show the reproducibility of the valve and sensor functions and support the system's potential as a chronic implant to replace standard shunt systems.

Hydrocephalus surveillance following CSF diversion: a modified Delphi study.

OBJECTIVE: Long-term follow-up is often recommended for patients with hydrocephalus, but the frequency of clinical follow-up, timing and modality of imaging, and duration of surveillance have not been clearly defined. Here, the authors used the modified Delphi method to identify areas of consensus regarding the modality, frequency, and duration of hydrocephalus surveillance following surgical treatment. METHODS: Pediatric neurosurgeons serving as institutional liaisons to the Hydrocephalus Clinical Research Network (HCRN), or its implementation/quality improvement arm (HCRNq), were invited to participate in this modified Delphi study. Thirty-seven consensus statements were generated and distributed via an anonymous electronic survey, with responses structured as a 4-point Likert scale (strongly agree, agree, disagree, strongly disagree). A subsequent, virtual meeting offered the opportunity for open discussion and modification of the statements in an effort to reach consensus (defined as ≥ 80% agreement or disagreement). RESULTS: Nineteen pediatric neurosurgeons participated in the first round, after which 15 statements reached consensus. During the second round, 14 participants met virtually for review and discussion. Some statements were modified and 2 statements were combined, resulting in a total of 36 statements. At the conclusion of the session, consensus was achieved for 17 statements regarding the following: 1) the role of standardization; 2) preferred imaging modalities; 3) postoperative follow-up after shunt surgery (subdivided into immediate postoperative imaging, delayed postoperative imaging, routine clinical surveillance, and routine radiological surveillance); and 4) postoperative follow-up after an endoscopic third ventriculostomy. Consensus could not be achieved for 19 statements. CONCLUSIONS: Using the modified Delphi method, 17 consensus statements were developed with respect to both clinical and radiological follow-up after a shunt or endoscopic third ventriculostomy. The frequency, modality, and duration of surveillance were addressed, highlighting areas in which no clear data exist to guide clinical practice. Although further studies are needed to evaluate the clinical utility and cost-effectiveness of hydrocephalus surveillance, the current study provides a framework to guide future efforts to develop standardized clinical protocols for the postoperative surveillance of patients with hydrocephalus. Ultimately, the standardization of hydrocephalus surveillance has the potential to improve patient care as well as optimize the use of healthcare resources.

Normally shaped heads with no sutures, normally shaped heads with abnormal sutures, and abnormally shaped heads with normal sutures.

UNLABELLED: We present a series of children whose head shapes and suture status do not make sense. There were 3 patients with complete absence of sutures and normal head shapes. One patient was evaluated for microcephaly at 6 years of age. In the second, the absence of sutures was discovered on workup for headaches at 8 years of age. The third underwent x-ray imaging for parasagittal bony nodules at 1 month of age. The head circumferences fell at the 4th, 25th, and 50th percentiles, respectively. The 2 older children were in normal classes, and the youngest was meeting milestones appropriately. We encountered 3 patients with fusion of the sagittal suture and normal head shapes. One had a flattened occiput, the second patient was thought to be brachycephalic, and the third was macrocephalic. Head circumferences were at the fourth, 50th, and 75th percentiles. The patient with head circumference at the fourth percentile had fetal alcohol syndrome and speech delay. The other 2 were developing normally with follow-up of 14 months. Finally, 3 patients underwent surgery for characteristic craniosynostotic head shapes and were found to have patent sutures at surgery. One patient had classic unilateral coronal synostosis and a patent suture on the side of the defect. The second patient had Crouzon syndrome with characteristic head shape, but open coronal sutures. The third patient had the appearance of bicoronal synostosis, with a patent suture on one side. They have had good results from their craniofacial reconstructions at 24, 12, and 6 months' follow-up. CONCLUSIONS: We have no explanation for these interesting findings.

Three-Dimensionally Printed Microelectromechanical-System Hydrogel Valve for Communicating Hydrocephalus.

Hydrocephalus (HCP) is a chronic neurological brain disorder caused by a malfunction of the cerebrospinal fluid (CSF) drainage mechanism in the brain. The current standard method to treat HCP is a shunt system. Unfortunately, the shunt system suffers from complications including mechanical malfunctions, obstructions, infections, blockage, breakage, overdrainage, and/or underdrainage. Some of these complications may be attributed to the shunts' physically large and lengthy course making them susceptible to external forces, siphoning effects, and risks of infection. Additionally, intracranial catheters artificially traverse the brain and drain the ventricle rather than the subarachnoid space. We report a 3D-printed microelectromechanical system-based implantable valve to improve HCP treatment. This device provides an alternative approach targeting restoration of near-natural CSF dynamics by artificial arachnoid granulations (AGs), natural components for CSF drainage in the brain. The valve, made of hydrogel, aims to regulate the CSF flow between the subarachnoid space and the superior sagittal sinus, in essence, substituting for the obstructed arachnoid granulations. The valve, operating in a fully passive manner, utilizes the hydrogel swelling feature to create nonzero cracking pressure, PT ≈ 47.4 ± 6.8 mmH2O, as well as minimize reverse flow leakage, QO ≈ 0.7 µL/min on benchtop experiments. The additional measurements performed in realistic experimental setups using a fixed sheep brain also deliver comparable results, PT ≈ 113.0 ± 9.8 mmH2O and QO ≈ 3.7 µL/min. In automated loop functional tests, the valve maintains functionality for a maximum of 1536 cycles with the PT variance of 44.5 mmH2O < PT < 61.1 mmH2O and negligible average reverse flow leakage rates of ∼0.3 µL/min.

Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy for the Treatment of Hypothalamic Hamartomas: A Retrospective Review.

BACKGROUND: Hypothalamic hamartomas (HH) are rare lesions associated with treatment-resistant epilepsy. Open surgery results in modest seizure control (about 50%) but has a significant associated morbidity. Radiosurgery is limited to a subset of patients due to latent therapeutic effects. Magnetic resonance imaging-guided laser interstitial thermal therapy (LITT) offers a novel minimally invasive option. OBJECTIVE: To evaluate a single center's outcomes for the LITT treatment of HH. METHODS: We retrospectively reviewed our experience with LITT for the treatment of HH using our institution's prospectively maintained patient database. RESULTS: Eighteen patients (mean age, 21.1 yr; median age, 11 yr) underwent 21 total LITT treatments for HH. Mean follow-up was 17.4 mo. The length of stay was 1 night for 16 (89%) patients. At the end of follow-up, 11 of 18 patients (61%) had full disconnection of the HH, and 12 of 15 (80%) patients with gelastic seizures and 5 (56%) of 9 patients with nongelastic seizures were seizure free (International League Against Epilepsy Class 1). Immediate complications included a 39% (7/18) incidence of neurological deficits, including 1 case of hemiparesis. At the end of follow-up, 22% of patients (4/18) had persistent deficits. The hypothyroidism that occurred was delayed in 11% of patients (2/18), as was short-term memory loss (22%, 4/18) and weight gain (22%, 4/18). CONCLUSION: LITT therapy for HH can achieve excellent rates of seizure control with low morbidity and a short postoperative stay in a majority of patients. Additional research is needed to assess the durability of results and the full spectrum of cognitive outcomes.

Arachnoid cysts: spontaneous resolution distinct from traumatic rupture. Case report.

Although many arachnoid cysts are discovered incidentally and require no intervention, a small subset has been known to rupture. Note that rupture can occur either spontaneously or in association with trauma. Based on a review of the literature on ruptured arachnoid cysts, it appears that patients with middle fossa cysts are more likely to experience symptomatic traumatic rupture than those with cysts in other locations. Middle fossa cysts are more commonly associated with hemispheric subdural collections and hematomas than are any other cysts. The authors report on two representative cases illustrating the distinct presentation, imaging characteristics, and management of these cysts.

Surgical management of arteriovenous malformations in children.

OBJECT: Children compose 3 to 20% of the patients with arteriovenous malformations (AVMs); however, AVMs are responsible for 30 to 50% of intracranial hemorrhages in children. METHODS: The medical records of 82 children with 84 AVMs treated surgically between 1983 and 2005 were reviewed. Fifty-two patients (63%) presented with hemorrhage, 13.4% presented with seizures, and AVMs in 12% were found incidentally. Patients with brainstem lesions presented at a significantly younger age (p = 0.002) than those harboring lesions in other locations. Frontal lobe lesions were significantly smaller than those in other locations, and thalamic lesions were significantly larger (p = 0.012 and 0.005, respectively). Most patients with Spetzler-Martin Grades I to III lesions underwent craniotomy only. Half of the patients with Grade IV and V lesions underwent embolization, craniotomy, and radiosurgery. The mean follow-up period was 43 months. Postoperatively, the initial obliteration rate was 65%, with a long-term obliteration rate of 90%. The perioperative mortality rate was 3.7%. Altogether, 81% of patients had excellent outcomes, and patients with Grade I lesions had the best outcomes. Of the 52 patients who presented with hemorrhage, 17% had fair or poor outcomes. The recurrence rate was 5.6%. CONCLUSIONS: Children with AVMs may be more prone than adults to present with a hemorrhage and to experience recurrence of the lesion after treatment. The authors favor resection for most AVMs in children and use embolization as a preoperative strategy for Grades II to V lesions treated surgically. Prehemorrhagic Grade IV and V lesions may best be treated conservatively and observed carefully for the development of symptoms. Long-term follow up of all patients is essential.

Bedside twist drill craniostomy for chronic subdural hematoma: a comparative study.

BACKGROUND: Although the bedside twist drill craniostomy is used to treat chronic subdural hematomas, the efficacy of this technique has not been compared with that of standard treatments (operative bur hole or craniotomy). METHODS: Twist drill craniostomy was compared with operative bur hole or craniotomy in a prospective nonrandomized trial. The inclusion criteria were computed tomographic evidence of chronic subdural hematoma (isodense or hypodense compared with brain) and symptoms indicating the need for drainage. Selection of the procedure depended on the on-call surgeon's preference. Clinical success of the procedure, recurrence, length of hospitalization, complications, and neurologic outcome were compared. RESULTS: Between August 2001 and October 2002, 79 consecutive patients with 91 chronic subdural hematomas were treated (67 unilateral and 12 bilateral) at our institution. Fifty-five patients were treated with twist drill craniostomy and 24 with bur hole or craniotomy. There were no differences in the mean age of presentation, thickness of hematoma, length of hospitalization, reoperation rate, mortality rates, or ability to be discharged to home between the 2 groups. There was no difference in the neurologic outcomes in the 57 of the 79 patients available for follow-up. CONCLUSIONS: Twist drill craniostomy performed at the bedside is just as effective in treating chronic subdural hematomas as bur holes or craniotomy in the operating room. This procedure can most often be the first line of treatment in patients with symptomatic chronic subdural hematomas.

The evolution of endovascular treatment for intracranial arteriovenous malformations.

Endovascular therapy for arteriovenous malformations (AVMs) remains a relatively new approach. Beginning in the 1960s with the use of flow-directed techniques for selective embolization, hemodynamic alterations have been used to treat these lesions. In every aspect of treatment, technological advances, including catheters, embolic materials, angiography suites, and pharmacological agents, have improved outcomes while lowering the risk to patients. In this article, the authors review the technical evolution of endovascular AVM therapy. Developments in embolic materials, beginning with foreign bodies and autografts and continuing through to highly engineered contemporary substances, are discussed. Finally, changes in treatment paradigms that have occurred over the years are traced. Within neurosurgery, this specialty has shown some of the fastest growth and development in recent decades. As minimally invasive approaches are embraced in all areas of medicine, it is clear that this treatment modality will continue to be refined.

Spinal cord compression from traumatic anterior cervical pseudomeningoceles. Report of three cases.

Pseudomeningoceles rarely develop after cervical trauma; in all reported cases the lesions have extended outside the spinal canal. The authors report the first known cases of anterior cervical pseudomeningoceles contained entirely within the spinal canal and causing cord compression and neurological injury. The authors retrospectively reviewed the cases of three patients with traumatic cervical spine injuries and concomitant compressive anterior pseudomeningoceles. The lesion was recognized in the first case when the patient's neurological status declined after he sustained a severe atlantoaxial injury; the pseudomeningocele was identified intraoperatively and decompressed. After the decompressive surgery, the patient's severe tetraparesis partially resolved. In the other two patients diagnoses of similar pseudomeningoceles were established by magnetic resonance imaging. Both patients were treated conservatively, and their mild to moderate hemiparesis due to the pseudomeningocele-induced compression abated. The high incidence of anterior cervical pseudomeningoceles seen at the authors' institution within a relatively brief period suggests that this lesion is not rare. The authors believe that it is important to recognize the compressive nature of these lesions and their potential to cause devastating neurological injury.

De novo presentation of an arteriovenous malformation. Case report and review of the literature.

The authors report the case of a patient with a de novo arteriovenous malformation (AVM), indicating that the origin of these lesions may not always be congenital. A 3-year-old girl who was struck by a car suffered a mild head injury and experienced posttraumatic epilepsy. The initial magnetic resonance (MR) image obtained in this child revealed only a small contusion in the left frontal lobe. Intractable epilepsy subsequently developed. A second MR image obtained almost 4 years after the injury demonstrated an AVM in the right posterior temporal lobe that was verified using angiography. The lesion was classified as a Spetzler-Martin Grade III AVM. The patient underwent embolization of the feeding vessels followed by gamma knife surgery. Fourteen months after treatment she was asymptomatic. Follow-up MR images demonstrate no evidence of an AVM and no changes in the white matter. This case presents a de novo AVM that developed within approximately 4 years. The findings indicate that AVMs may not always be congenital and reinforce the concept that the natural history of AVMs is dynamic. Lesions may appear de novo, grow, and thrombose spontaneously.