Spontaneous obliteration of brain arteriovenous malformations: illustrative cases.

BACKGROUND: Spontaneous angiographic obliteration of a brain arteriovenous malformation (AVM) is considered a rare outcome, with most cases in the literature related to prior hemorrhage in small brain AVMs. The authors present a prospective, single center, consecutive case series. The clinical course and radiographic features of four cases with spontaneous obliteration of brain AVM were analyzed. OBSERVATIONS: The median age of patients in this series was 47.6 years, with an equal gender split. The median maximum brain AVM diameter was 2 cm. The median time to spontaneous obliteration was 26 months, with hemorrhage preceding this in three out of four cases and a prolonged latency in the only case with a nidus size larger than 3 cm and no hemorrhage. LESSONS: The present study provides additional information to allow clinicians to counsel patients about the rare outcomes of conservative management. This work extends our understanding of when this phenomenon can occur by reporting on the differences associated with spontaneous obliteration of larger AVMs.

First reported case of hydrocephalus in jointly diagnosed bacterial meningitis and a colloid cyst: how Ockham's razor became Hickam's dictum.

We report the first case in the literature of acute hydrocephalus due to a simultaneous diagnosis of bacterial (not asceptic) meningitis and a colloid cyst. Diagnosing disease is the cornerstone skill of a medical practitioner. Both education and experience allow for sharpening of this skill throughout years of medical practice. Disease is fraught with nuances and inconsistencies which can render an accurate diagnosis a difficult task. Medical practitioners can be guilty of cognitive biases such as Ockham's razor. We present the case of a patient with an initial diagnosis of obstructive hydrocephalus secondary to a colloid cyst. However, pneumococcal meningitis blunted Ockham's razor in favour of Hickam's dictum.

Trans-Cranial Embolisation of a Complex Transverse Sigmoid Sinus Dural Arteriovenous Fistula by Direct Puncture of the Superior Sagittal Sinus.

This technical note describes a direct puncture of the superior sagittal sinus (SSS) to treat a complex dural arteriovenous fistula (dAVF). A 40-year-old female was admitted having a history of increasing confusion. Computer tomography revealed enlargement of the right superior ophthalmic vein and magnetic resonance imaging demonstrated extensive bilateral hemispheric venous engorgement. Digital subtraction angiography (DSA) demonstrated a high flow dAVF involving the right transverse sinus. There was extensive cortical venous rerouting with venous sinus occlusion at the right transverse and sigmoid junction. Under general anesthesia, the sinus was exposed and catheterized. The angiography catheter was fed over the guide wire into the sinus. The remaining right sigmoid and transverse sinus were obliterated using a combination of microcoils and Onyx®. She made a good postoperative recovery, and a repeat DSA at 30 days postoperatively showed evidence of the meningohypophyseal trunk but complete occlusion of the fistula. A check DSA 2 years later confirmed no evidence of a residual fistula. Our case demonstrates the potential use of the SSS as a novel conduit to treat distant targets.

Atypical adult medulloblastoma.

Medulloblastomas are malignant primitive neuro-ectodermal neoplasms of childhood. In adults, clinical manifestations, imaging and prognosis can be different from that observed in children. Three adult patients with confirmed diagnoses of medulloblastoma are discussed in this report. They presented with unusually prolonged clinical courses and with imaging more suggestive of L'hermitte-Duclos disease. Medulloblastoma should be considered in all adults with posterior fossa masses despite having clinical and radiological features suggestive of a low-grade tumour. Definitive diagnosis requires histological confirmation in all cases.

Stereotactic radiosurgery XVI: Isodosimetric comparison of photon stereotactic radiosurgery techniques (gamma knife vs. micromultileaf collimator linear accelerator) for acoustic neuroma--and potential clinical importance.

PURPOSE: Two stereotactic photon radiation therapy methods are currently in practice for the treatment of acoustic neuroma. In the 1990s, our data and those of others demonstrated isodosimetric advantages for gamma knife technology over linear accelerator methodology. Since then, the introduction of micromultileaf collimator technology has improved the conformity of the linear accelerator method such that the isodosimetric differences between the two techniques have narrowed. MATERIALS AND METHODS: In this study, modern gamma knife isodosimetry was compared to that of modern linac technology (conformal fixed fields and dynamic arcs) for the therapy of acoustic neuroma. This is an unusual target in that a special sensory nerve (holding the key to hearing preservation) frequently runs through the targeted volume, unlike the majority of other stereotactic radiation therapy targets. This was a single-dose prescription comparison; the perceived extra benefit of fractionation (a technique not routinely available to the gamma knife) was thereby abrogated. RESULTS: Although the gamma knife technique maintained a slight, but statistically significant, advantage with regard to dose conformity (p < 0.02) (at the debatable cost of a lower minimum target dose), the much higher internal dose gradient (high maximum dose to prescription dose [MD:PD] ratio) could be interpreted as a disadvantage with respect to hearing preservation, although advantageous with regard to tumor ablation. Of the two linac methods, the dynamic arc method gave a statistically significant advantage over the fixed-field method as regards conformity (p < 0.05), at the expense of a slightly higher brainstem dose (an average of 12.4 Gy, cf. 11.7 Gy for fixed fields), but this result was not statistically significant. No significant difference was seen in the MD:PD ratio for the two single-isocenter linac techniques. CONCLUSIONS: Gamma knife methodology remains well validated, with very good isodosimetry, but when hearing preservation is important, the improving linac technologies will compete with the gamma knife for optimal therapy. In these circumstances, the minor differences in isodosimetry between the two techniques will become important.