Reperfusion injury following cerebral ischemia: pathophysiology, MR imaging, and potential therapies

INTRODUCTION: Restoration of blood flow following ischemic stroke can be achieved by means of thrombolysis or mechanical recanalization. However, for some patients, reperfusion may exacerbate the injury initially caused by ischemia, producing a so-called “cerebral reperfusion injury”. Multiple pathological processes are involved in this injury, including leukocyte infiltration, platelet and complement activation, postischemic hyperperfusion, and breakdown of the blood–brain barrier. METHODS/RESULTS AND CONCLUSIONS: Magnetic resonance imaging (MRI) can provide extensive information on this process of injury, and may have a role in the future in stratifying patients’ risk for reperfusion injury following recanalization. Moreover, different MRI modalities can be used to investigate the various mechanisms of reperfusion injury. Antileukocyte antibodies, brain cooling and conditioned blood reperfusion are potential therapeutic strategies for lessening or eliminating reperfusion injury, and interventionalists may play a role in the future in using some of these therapies in combination with thrombolysis or embolectomy. The present review summarizes the mechanisms of reperfusion injury and focuses on the way each of those mechanisms can be evaluated by different MRI modalities. The potential therapeutic strategies are also discussed

Palatal myoclonus: report of two cases Mioclonia palatal: relato de dois casos

We describe two cases of palatal myoclonus (PM), one essential and another secondary to a stroke. Case 1: a 64 years old female who developed clicking sounds in both ears after a stroke and three years later on noticed a progressive involuntary movement of the throat associated with rhythmic contractions of the soft palate, muscles of tongue and throat. MRI showed an ischemic area in brainstem. The patient had a partial response to the use of sumatriptan 6 mg subcutaneously. Case 2: a 66 years old female who began with ear clicking at left ear that worsed slowly associated with tinnitus and arrhythmic movements of soft palate and an audible click at left ear. Brain MRI was normal; audiometry showed bilateral neurosensory loss. She was prescribed clonazepan 1 mg daily with complete recovery. Primary and secondary palatal myoclonus share the same clinical features but probably have different pathophysiological underlying mechanisms.<br>Descrevemos dois casos de mioclonia palatal (MP), um essencial e o outro secundário a acidente vascular cerebral (AVC). Caso1: mulher de 64 anos que desenvolveu cliques audíveis em ambos os ouvidos após um AVC e que três anos depois começou a apresentar movimentos involuntários do pálato, músculos do língua e garganta. A ressonância magnética (RNM) mostrou áreas de isquemia no tronco cerebral. A paciente apresentou resposta parcial e não duradoura ao uso subcutâneo de 6 mg de sumatriptano. Caso 2: mulher de 66 anos, com cliques audíveis no ouvido esquerdo que pioraram progressiva e lentamente associados com tinitus e movimentos mais ou menos rítmicos do pálato mole. A RNM encefálica era normal. A audiometria mostrou perda neurossensorial bilateral. Foi medicada com 1,0 mg de clonazepan diariamente com completa recuperação. MP primária e secundária compartilham das mesmas características clínicas, mas evidências sugerem que se devam a diferentes mecanismos fisiopatológicos