The cut flow index revisited: utility of intraoperative blood flow measurements in extracranial-intracranial bypass surgery for ischemic cerebrovascular disease.

OBJECTIVE: In extracranial-intracranial (EC-IC) bypass surgery, the cut flow index (CFI) is the ratio of bypass flow (ml/min) to donor vessel cut flow (ml/min), and a CFI ≥ 0.5 has been shown to correlate with bypass patency. The authors sought to validate this observation in a large cohort of EC-IC bypasses for ischemic cerebrovascular disease with long-term angiographic follow-up. METHODS: All intracranial bypass procedures performed at a single institution between 2003 and 2018 were reviewed. Demographic, clinical, angiographic, and operative data were recorded and analyzed according to bypass patency with univariate and multivariate statistical analyses. RESULTS: A total of 278 consecutive intracranial bypasses were performed during the study period, of which 157 (56.5%) were EC-IC bypasses for ischemic cerebrovascular disease. Intraoperative blood flow measurements were available in 146 patients, and angiographic follow-up was available at a mean of 2.1 ± 2.6 years after bypass. The mean CFI was significantly higher in patients with patent bypasses (0.92 vs 0.64, p = 0.003). The bypass patency rate was 83.1% in cases with a CFI ≥ 0.5 compared with 46.4% in cases with a CFI < 0.5 (p < 0.0001). Adjusting for age, sex, diagnosis, and single versus double anastomosis, the CFI remained a significant predictor of bypass patency (p = 0.001; OR 5.8, 95% CI 2.0-19.0). A low CFI was also associated with early versus late bypass nonpatency (p = 0.008). CONCLUSIONS: A favorable CFI portends long-term EC-IC bypass patency, while a poor CFI predicts eventual bypass nonpatency and can alert surgeons to potential problems with the donor vessel, anastomosis, or recipient bed during surgery.

Transtentorial herniation from tumefactive multiple sclerosis mimicking primary brain tumor.

BACKGROUND: Multiple sclerosis (MS) is a chronic central nervous system inflammatory demyelinating disease characterized by multiple lesions disseminated in time and space. The lesions often have characteristic imaging findings on magnetic resonance (MR) imaging and cerebrospinal fluid findings that lead to their diagnosis. At times, these lesions may resemble tumors due to their large size (>2 cm), significant vasogenic edema, and ring-enhancing MR imaging findings. Such lesions are described as tumefactive demyelinating lesions or tumefactive MS, and they are generally seen in aggressive forms of MS associated with rapid progression. CASE DESCRIPTION: We report an uncommon but clinically significant case of transtentorial brain herniation secondary to malignant cerebral edema from tumefactive MS in a 50-year-old woman. After the initial diagnosis of MS, the patient continued to have progression of her white matter lesions suggesting evolution of her MS despite treatment with intravenous (IV) steroids, IV immunoglobulin, and plasmapheresis. She was admitted to the hospital with a new, large, ring-enhancing lesion that displayed significant mass effect from vasogenic edema and progressed, necessitating a decompressive hemicraniectomy. CONCLUSION: Tumefactive MS presents a unique pathology that can often mimic primary brain tumors. Although these lesions affect white matter and infrequently cause a significant amount of mass effect, they can act like a tumor, causing edema that generates sufficient intracranial pressure to cause transtentorial herniation.

Thalamic cavernous malformations.

Cavernous malformations of the thalamus represent a particularly complex subset of cavernous malformations because of the highly eloquent nature of the involved tissue and their deep location. The decision about whether to operate on any individual lesion depends on the specific location of the lesion within the thalamus, the nature of the patient's symptoms, and the patient's history. When surgery is recommended, the approach must be chosen carefully. Each part of the thalamus is reached by a different surgical approach. These approaches include the orbitozygomatic approach to the anteroinferior thalamus, the anterior interhemispheric transcallosal approach to the medial thalamus, the anterior contralateral interhemispheric transcallosal approach to the lateral thalamus, the posterior interhemispheric transcallosal approach to the posterosuperior thalamus, the parieto-occipital transventricular approach to the lateral posteroinferior thalamus, and the suboccipital supracerebellar infratentorial/transtentorial approach to the medial posteroinferior thalamus. Careful attention to safe entry zones and image guidance can allow safe removal of these lesions when necessary.

Multimodality management of cerebral arteriovenous malformations.

Arteriovenous malformations (AVMs) of the brain are diverse lesions that vary widely in location, size, and complexity. Treatment options for AVMs are correspondingly complex. Complete elimination of an AVM is required to protect patients from future hemorrhage. Decisions about whether to treat and, if so, how to treat these lesions depend on the characteristics of the patient and the specific characteristics of the AVMs. The characteristics of AVMs are often summarized through grading systems. Some AVMs can be managed conservatively, whereas others can be managed with microsurgical resection, radiosurgical ablation, or endovascular embolization, either individually or in combination. Some AVMs may also be treated with partial therapy to reduce the risk of hemorrhage or to ameliorate symptoms. In this chapter, we review the key factors that influence whether and how to manage AVMs with multimodality treatment.

Effective Surgical Management of Competitive Venous Outflow Restriction After Radiosurgery for Cerebral AVMs: Report of 2 Cases.

BACKGROUND: Intracranial arteriovenous malformations (AVMs) are complex pathologies. For patients who do not present with hemorrhage, treatment strategies are often predicated on reducing the risk of hemorrhage and minimizing morbidity. Outcomes vary according to the efficacy of treatment selected. Radiosurgical treatment of certain AVMs can result in incomplete obliteration and may also have only a minimal effect on the presenting nonhemorrhagic symptoms. CASE DESCRIPTIONS: We present 2 cases of patients with AVMs who were initially treated with radiosurgery. Both patients' primary clinical symptoms were headaches, which persisted after radiosurgical treatment but abated after subsequent microsurgical resection with or without endovascular embolization. CONCLUSION: Venous outflow obstruction is likely a sizable contributive factor in occipital AVMs among patients who present with headaches and symptoms of intracranial hypertension. Because these high-flow lesions may be suboptimally responsive to stereotactic radiosurgery, microsurgical resection, with or without adjunctive endovascular embolization, should be considered as an initial and definitive treatment strategy. Optimal outcomes may be achieved in patients with a visual deficit that is anatomically correlated to their AVMs.