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Samer K. Elbabaa, Angela D. Riggs and Ali G. Saad

Tuberous sclerosis complex (TSC) is a genetic neurocutaneous disorder that commonly affects the CNS. The most commonly associated brain tumors include cortical tubers, subependymal nodules, and subependymal giant cell astrocytomas (SEGAs). The authors report an unusual case of recurrent meningitis due to a tuber-containing encephalocele via the posterior wall of the frontal sinus.

An 11-year-old girl presented with a history of TSC and previous SEGA resection via interhemispheric approach. She presented twice within 4 months with classic bacterial meningitis. Cerebrospinal fluid cultures revealed Streptococcus pneumoniae. Computed tomography and MR imaging of the brain showed a right frontal sinus encephalocele via a posterior frontal sinus wall defect. Both episodes of meningitis were treated successfully with standard regimens of intravenous antibiotics. The neurosurgical service was consulted to discuss surgical options.

Via a bicoronal incision, a right basal frontal craniotomy was performed. A large frontal encephalocele was encountered in the frontal sinus. The encephalocele was herniating through a bony defect of the posterior sinus wall. The encephalocele was ligated and resected followed by removing frontal sinus mucosa and complete cranialization of frontal sinus. Repair of the sinus floor was conducted with fat and pericranial grafts followed by CSF diversion via lumbar drain. Histopathology of the resected encephalocele showed a TSC tuber covered with respiratory (frontal sinus) mucosa. Tuber cells were diffusely positive for GFAP. The patient underwent follow-up for 2 years without evidence of recurrent meningitis or CSF rhinorrhea.

This report demonstrates that frontal tubers of TSC can protrude into the frontal sinus as acquired encephaloceles and present with recurrent meningitis. To the authors' knowledge, recurrent meningitis is not known to coincide with TSC. Careful clinical and radiographic follow-up for frontal tubers in patients with TSC is recommended.

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Nathan R. Selden

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Brian A. O'Shaughnessy, Sean A. Salehi, Saad Ali and John C. Liu

✓ Chiari I malformation, a congenital disorder involving downward displacement of the cerebellar tonsils through the foramen magnum, is often treated surgically by performing suboccipital craniectomy and C-1 laminectomy. The authors report two cases in which fracture of the anterior atlantal arch occurred during the postoperative period following Chiari I decompression and C-1 laminectomy causing significant neck pain. The findings indicate that interruption of the integrity of the posterior arch of C-1, iatrogenically or otherwise, confers increased risk of anterior arch fracture. A C-1 fracture should therefore be considered in the differential diagnosis of posterior cervical pain in patients who have previously undergone decompression for Chiari I malformation.

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Melissa M. Stamates, David M. Frim, Carina W. Yang, Gregory L. Katzman and Saad Ali


Tethered cord syndrome (TCS) is a neurosurgical disorder with varied clinical manifestations believed to result from vascular compromise due to stretch forces on the spinal cord. Conventional supine MRI findings may include a low-lying conus medullaris, thickened or fat-infiltrated filum terminale, or lipoma; however, imaging sensitivity and specificity for tethered cord can be low. The purpose of this study was to evaluate the utility of prone MRI in the diagnosis of tethered and retethered spinal cord.


Medical records were reviewed in 41 patients who underwent surgical release of tethered cord and in whom preoperative prone MRI sequences were available. Patients were divided into Group 1 (new TCS diagnosis) and Group 2 (recurrent TCS after previous untethering). Absolute conus ventral motion and motion as a percentage of canal width between supine and prone positions was measured in these 2 groups via sagittal T2-weighted sequences; these groups were compared with 30 consecutive patients (Group 3) who were classified as the normal control group.


The mean ventral motion was as follows: Group 1 (absolute: 0.5 ± 0.5 mm [range 0–2.4 mm]; canal percentage: 3.7% ± 3.9% [range 0%–16.3%]); Group 2 (absolute: 0.4 ± 0.7 mm [range 0–2.6 mm]; canal percentage: 2.2% ± 3.7% [range 0%–14.0%]); and Group 3 (absolute: 3.4 ± 1.3 mm [range 1.4–5.6 mm]; canal percentage: 22.0% ± 7.2% [range 10.5%–36.1%]). Whereas 38/41 surgically treated patients with TCS had diminished (< 10% canal width) ventral motion on preoperative MRI, 30/30 controls had > 10% canal width motion. Sensitivity and specificity were thereby calculated as 92.7% and 100%, respectively.


In the present series, prone imaging is found to be a sensitive and specific tool, and the authors believe it may have a role as supportive evidence in the diagnosis of tethered and retethered spinal cord.

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Samer K. Elbabaa, Murat Gokden, John R. Crawford, Santosh Kesari and Ali G. Saad


Radiation-associated meningiomas (RAMs) arise after treatment with radiation to the cranium and are recognized as clinically separate from sporadic meningiomas. Compared with their sporadic counterparts, RAMs are often aggressive or malignant, likely to be multiple, and have a high recurrence rate. However, limited information exists about the clinical, pathological, and cytogenetic features of RAMs in pediatric patients. The authors report the findings in 9 children with meningiomas following therapeutic radiation to the cranium. In addition, they performed a critical review of the English language literature on pediatric RAMs.


Medical files were searched for patients who demonstrated meningiomas after a history of radiation to the brain. Only those patients in whom a meningioma occurred before the age of 18 years were included in this study. Clinical and demographic data along with the MIB-1 labeling index and cytogenetic studies were evaluated.


The patients consisted of 5 males and 4 females with a median age of 5 years (range 2–10 years) at radiation therapy. The latency period was a median of 10 years after radiation therapy (range 6–13 years). The MIB-1 labeling index was a median of 6.6% (range 4%–10%). Five patients (55.6%) displayed multiple meningiomas at the first presentation. Histological types included clear cell meningioma in 1 patient, fibroblastic meningioma in 2, chordoid meningioma in 2, meningothelial meningioma in 7 (atypical in 2 cases), xanthomatous meningioma in 1, and chordoid meningioma in 1. Cytogenetic studies showed that the loss of 22q12.2 was the most common abnormality (3 patients), followed by complex cytogenetic abnormalities (2 patients) and rearrangements between chromosomes 1 and 12 (1 patient) and a 1p deletion (1 patient).


In contrast to RAMs occurring in adults, those in pediatric patients show an increased incidence of multiplicity on first presentation and unusual histological variants, some of which are described here for the first time. There was no difference in the MIB-1 labeling index in children with RAMs as compared with that in children with non-RAMs.

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Brian V. Nahed, Aneela Darbar, Robert Doiron, Ali Saad, Caroline D. Robson and Edward R. Smith

✓Choroid plexus cysts are common and typically asymptomatic abnormal folds of the epithelial lining of the choroid plexus. Rarely, these cysts may gradually enlarge and cause outflow obstruction of cerebrospinal fluid. The authors present a case of a large choroid plexus cyst causing acute hydrocephalus in a previously healthy 2-year-old boy. The patient presented with markedly declining mental status, vomiting, and bradycardia over the course of several hours. Computed tomography scans demonstrated enlarged lateral and third ventricles with sulcal effacement, but no obvious mass lesions or hemorrhage. There was no antecedent illness or trauma. A right frontal external ventricular drain was placed in the patient, resulting in decompression of only the right lateral ventricle. Magnetic resonance (MR) imaging demonstrated a lobulated cyst arising from the choroid plexus of the left lateral ventricle and herniating through the foramen of Monro into the third ventricle, occluding both the foramen of Monro and the cerebral aqueduct. The patient underwent an endoscopic fenestration of the cyst, and histological results confirmed that it was a choroid plexus cyst. Postoperative MR imaging showed a marked reduction in the cyst size. The cyst was no longer in the third ventricle, the foramen of Monro and the aqueduct were patent, and the ventricles were decompressed. The patient was discharged home with no deficits. To the authors' knowledge, there are no previous reports of a choroid plexus cyst causing acute hydrocephalus due to herniation into the third ventricle. This case is illustrative because it describes this entity for the first time, and more importantly highlights the need to obtain a diagnosis when a patient presents with acute hydrocephalus without a clear cause.

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John K. Hopkins, Ali Shaibani, Saad Ali, Saquib Khawar, Richard Parkinson, Stephen Futterer, Eric J. Russell and Christopher Getch

✓The authors report a unique case of subarachnoid hemorrhage caused by a traumatic pseudoaneurysm of the ophthalmic artery, which was successfully treated with coil embolization. Clinical and imaging features, as well as the relevant literature, are described.