Bleeding patterns in ruptured posterior fossa aneurysms: a CT study

Computed tomography of the brains in 20 patients with acute rupture of posterior fossa aneurysms was reviewed and analyzed retrospectively. Findings were compared with those from 44 cases described in the literature and with the findings in ruptured supratentorial aneurysms. Extravasated blood was observed in 19 of 20 patients (95%); intraventricular hemorrhage (IVH) in 17 of 20 (85%); and subarachnoid hemorrhage (SAH) in 13 of 20 (65%). These values were significantly higher than those previously reported and suggest that, during the acute phase of rupture, extravasated blood may be detected with the same frequency in either infratentorial or supratentorial ruptured aneurysms. Subarachnoid hemorrhage was accompanied by IVH, prominent in the fourth ventricle and without intraparenchymal hematoma, in 11 patients (55%). This pattern is highly suggestive of ruptured posterior fossa aneurysms. Intraventricular hemorrhage without SAH was noted in five patients (25%) and specifically represented ruptured posterior inferior cerebellar artery aneurysms. Subarachnoid hemorrhage without IVH was noted in only two patients (10%).     

Traumatic carotid-cavernous fistula

Carotid-cavernous fistulas are uncommon, although not rare, complications of trauma to the base of the skull; they may result in cranial nerve palsies, blindness, and occasionally in devastating subarachnoid hemorrhage. We have presented a case of carotid-cavernous fistula in a 17-year-old boy, treated successfully with balloon embolization. Although surgical treatment was advocated in the past, the low morbidity and high success rate of percutaneous balloon embolization currently make this the procedure of choice.     

Medication adherence as a learning process: insights from cognitive psychology

Non-adherence to medications is one of the largest contributors to sub-optimal health outcomes. Many theories of adherence include a ‘value–expectancy’ component in which a patient decides to take a medication partly based on expectations about whether it is effective, necessary, and tolerable. We propose reconceptualising this common theme as a kind of ‘causal learning’ – the patient learns whether a medication is effective, necessary, and tolerable, from experience with the medication. We apply cognitive psychology theories of how people learn cause–effect relations to elaborate this causal-learning challenge. First, expectations and impressions about a medication and beliefs about how a medication works, such as delay of onset, can shape a patient’s perceived experience with the medication. Second, beliefs about medications propagate both ‘top-down’ and ‘bottom-up’, from experiences with specific medications to general beliefs about medications and vice versa. Third, non-adherence can interfere with learning about a medication, because beliefs, adherence, and experience with a medication are connected in a cyclic learning problem. We propose that by conceptualising non-adherence as a causal-learning process, clinicians can more effectively address a patient’s misconceptions and biases, helping the patient develop more accurate impressions of the medication.