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Background and Purpose-In acute stroke patients treated with intravenous tissue plasminogen activator (t-PA), early recanalization of occluded arteries can improve the clinical outcome. The magnetic susceptibility effect of deoxygenated hemoglobin in red thrombi can present as hypointense signals on T2*-weighted gradient echo imaging. We investigated whether the gradient echo imaging M1 susceptibility vessel sign (M1 SVS) can predict no early recanalization after t-PA infusion. Methods-Patients with internal carotid artery and M1 occlusion were prospectively studied. MRI studies, including DWI, T2*, and MRA, were performed before and within 30 minutes and 24 hours after t-PA infusion. The NIHSS score was obtained before and 7 days after t-PA administration. The relationship between the presence of the M1 SVS and no early recanalization and patient outcome was examined. Results-A total of 48 patients (29 men; mean age, 74.6Ϯ11.2 years) were enrolled. M1 SVS was present in 13 (27.1%) patients and absent in 35 (72.9%) patients. There were no significant differences in clinical characteristics between the 2 groups. Follow-up MRA within 30 minutes after t-PA infusion revealed that 20 (57.1%) of the 35 patients without the M1 SVS had early recanalization, but that none of the 13 patients with the M1 SVS had early recanalization (Pϭ0.0002). Seven days after t-PA infusion, dramatic improvement was more frequently observed in patients without the M1 SVS (51.4%) than in those with the M1 SVS (0%, Pϭ0.0007). Conclusion-The M1 SVS on T2* appears to be a strong predictor for no early recanalization after t-PA therapy.

Background and Purpose: Patients with unknown onset time would be able to receive intravenous thrombolysis when showing diffusion-weighted imaging (DWI)/fluid-attenuated inversion recovery (FLAIR) mismatch. Methods: Consecutive acute stroke patients with unknown onset time were prospectively enrolled. We defined patients as having unknown onset time when the last known normal time (LNT) was not consistent with the first found abnormal time (FAT). Only patients with anterior-circulation stroke and presence of arterial lesion were enrolled. Intravenous thrombolysis was conducted within 3 h from FAT if the patient showed DWI/FLAIR mismatch. Results: From June 2009 to May 2010, 10 patients [median age, 84 years (interquartile range, IQR, 64–90); National Institutes of Health Stroke Scale (NIHSS) score, 14 (IQR, 9–19)] were enrolled. Subjects included 4 patients who developed stroke during sleep, 5 with disturbance of consciousness, and 1 with aphasia. Median interval between LNT and thrombolysis was 5.6 h (IQR, 4.5–9.8) and median interval between FAT and thrombolysis was 2.5 h (IQR, 2.1–2.8). Three patients had internal carotid artery occlusion, 5 had M1 occlusion, and 2 had M2 occlusion. Early recanalization within 24 h was seen in 7 patients (complete recanalization, n = 4; partial recanalization, n = 3). No patients experienced symptomatic cerebral hemorrhage within 48 h. At day 7, 5 patients showed dramatic recovery (defined as ≧10-point reduction in total NIHSS score or score of 0 or 1). At 3 months, favorable outcome (modified Rankin scale score, 0–2) was seen in 4 patients. Conclusion: Acute stroke patients with DWI/FLAIR mismatch may be able to safely receive intravenous thrombolysis.

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ABSTRACT. A 3-month-old male Japanese cat with feline parvovirus infection, showing central and cervical nerve abnormalities, was diagnosed as hydrocephalus and syringomyelia by use of magnetic resonance imaging (MRI). The cat was maintained clinically by medical treatment even though he could not stand. The MRI scans obtained about 5 months later showed that the ventricles had increased in size and the cervical syrinx had extended into the thoracic spinal cord. Ventriculoperitoneal (VP) shunt was performed. One week after surgery, neurological conditions had improved. At the postoperative MR images, the ventricles had decreased in size and the syrinx in the cervical and thoracic spinal cord could no longer be seen. The cat was still alive and was able to walk well. KEY WORDS: feline, magnetic resonance imaging, syringomyelia.J. Vet. Med. Sci. 63(12): 1331-1334, 2001 Hydrocephalus is a term commonly used to describe a condition involving abnormal dilatation of the ventricular system within the cranium [11,15]. Viral infections such as feline infectious peritonitis (FIP) are a common cause of hydrocephalus in cats [15,18]. Syringomyelia has been defined as fluid-filled cavities in the substance of the spinal cord, with destruction of the nervous tissue [19]. Its cause is unknown, but it may be associated with or result from hydrocephalus [16,24]. Ventriculoperitoneal (VP) shunts are commonly used to divert the flow of cerebrospinal fluid (CSF) from the ventricles of the brain to the peritoneal cavity in human neurosurgery [11], and have proved to be an effective surgical treatment for hydrocephalus in dogs [15] and cats [23]. Several investigators [12,15,16,24] in the veterinary field have suggested magnetic resonance imaging (MRI) to be a useful technique for the antemortem diagnosis of several cranial and spinal disorders in animals. This article describes the clinical findings in, and management of, a cat with hydrocephalus and syringomyelia, together with temporal changes in MR images obtained before and after the insertion of a VP shunt.A 3-month-old male Japanese cat was referred because of severe ataxia following an inadvertent fall onto the floor from a height of about 2 m. The cat had not been vaccinated against any diseases. The owner stated that the cat had walked well until the event. Laboratory examination revealed neutrophilia (56,400/µl; Segmented neutrophils 99%, Lymphocytes 1%). Physical examination revealed severe muscular atrophy over the whole body and myotonus of all four limbs. Neurological examination revealed several cranial nerve abnormalities such as torticollis to the right, nystagmus and depression, and cervical nerve abnormalities such as clasp-knife rigidity of fore limbs. The menace response was absent, but the papillary light reflex and the palpebral reflex were normal. Asymmetry of the pupils was also observed. Patellar reflexes were exaggerated and flexor reflexes were detected in all four limbs. Elevated rectal temperatures (40.8, 40.6 and 39.6°C) were noted on days 7, 8 and 9, ...