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Introduction Up to 18% of spontaneous intracerebral hemorrhages are cryptogenic despite a thorough workup, usually noted in a lobar location. Although undetected on DSA, a significant proportion of these represent ruptured micro‐AVM/AVF or cavernous malformations that ultimately are amenable to surgical resection if detected on biopsy. However, occult cerebral amyloid angiopathy can also present similarly, and their management is markedly different. Methods We present a case of recurrent bilateral medial frontal hemorrhage in a patient without known cerebrovascular disease that evaded diagnosis despite hematologic evaluation, MRI, CTA, two DSAs, three clot evacuations with pathology, and brain biopsy. Results The patient is a 60‐year‐old previously healthy woman who presented with sudden onset right hemiparesis and speech arrest. CT revealed a left parasagittal hemorrhage. She was brought to the OR for clot evacuation. Pathology from the clot revealed blood vessels of multiple sizes consistent with meningeal vessels or underlying AVM/AVF. A 6‐vessel cerebral angiogram as unremarkable. The patient’s inpatient course was complicated by new onset Afib with RVR and asymptomatic DVT with PE, however no etiology of coagulopathy was detected. MRI brain showed no evidence of cerebral microbleed or other underlying pathology, noting only DWI + FLAIR hyperintensity in the left ACA territory. The patient was diagnosed with ACA territory stroke complicated by PH2‐type hemorrhagic conversion. She was initially placed on IV Heparin, before transition to apixaban uneventfully. She continued to recover in the hospital and was eventually discharged to rehab. She re‐presented 1 month later with worsening behavioral arrest and right hemiparesis. CT head revealed recurrence of left parasagittal ICH. She underwent clot evacuation in the OR again and repeat pathology was unrevealing. A repeat MRI showed only the evident bleed and a subtle hyperintensity in the right occipital cortex suspicious for an interval subacute occipital lobe stroke with laminar necrosis, ostensibly from Afib. She improved clinically and was discharged to rehab with a diagnosis of recurrent hemorrhage attributed to anticoagulant use and recent stroke. She was discharged this time on no anticoagulant or antiplatelets. She re‐presented 1 month later with sudden onset speech arrest, but now with left hemiparesis. CT revealed a right parasagittal hemorrhage. She was brought to the OR for emergent clot evacuation and parenchymal biopsy – which was initially normal. A repeat 6‐vessel DSA was again unremarkable as was repeat brain MRI. The patient’s parenchymal biopsy was sent for specific congo‐red and immunohistochemistry for beta‐amyloid. IHC revealed beta‐amyloid plaques in the parenchyma and vessel walls, confirming a diagnosis of CAA. Conclusion Apparently cryptogenic lobar hemorrhage may be caused by both occult micro‐AVM/fistula and CAA. As in this case, when a patient experiences recurrent DSA negative lobar hemorrhages, biopsy should be pursued. This case was particularly challenging given the anatomical plausibility of parasagittal AVM/fistula given its midline location and venous drainage, considering the patient’s evident predisposition to systemic venous thrombosis hemorrhagic venous infarction mimicking lobar ICH is also possible. We present this case to raise awareness of the potential need for early biopsy, especially in patients who may also require anticoagulation or antiplatelet medications.

Abstract Background Thrombolytic therapy with tissue plasminogen activator (tPA) benefits patients with acute ischemic stroke. However, tPA increases the risk for intracerebral bleeding and enhances post-ischemic neuronal injury if administered 3-4 hours after stroke. Therefore, combination therapies with tPA and neuroprotective agents have been considered to increase tPA's therapeutic window and reduce toxicity. The anticoagulant factor protein S (PS) protects neurons from hypoxic/ischemic injury. PS also inhibits N-methyl-D-aspartate (NMDA) excitotoxicity by phosphorylating Bad and Mdm2 which blocks the downstream steps in the intrinsic apoptotic cascade. To test whether PS can protect neurons from tPA toxicity we studied its effects on tPA/NMDA combined injury which in contrast to NMDA alone kills neurons by activating the extrinsic apoptotic pathway. Neither Bad nor Mdm2 which are PS's targets and control the intrinsic apoptotic pathway can influence the extrinsic cascade. Thus, based on published data one cannot predict whether PS can protect neurons from tPA/NMDA injury by blocking the extrinsic pathway. Neurons express all three TAM (Tyro3, Axl, Mer) receptors that can potentially interact with PS. Therefore, we studied whether PS can activate TAM receptors during a tPA/NMDA insult. Results We show that PS protects neurons from tPA/NMDA-induced apoptosis by suppressing Fas-ligand (FasL) production and FasL-dependent caspase-8 activation within the extrinsic apoptotic pathway. By transducing neurons with adenoviral vectors expressing the kinase-deficient Akt mutant AktK179A and a triple FKHRL1 Akt phosphorylation site mutant (FKHRL1-TM), we show that Akt activation and Akt-mediated phosphorylation of FKHRL1, a member of the Forkhead family of transcription factors, are critical for FasL down-regulation and caspase-8 inhibition. Using cultured neurons from Tyro3, Axl and Mer mutants, we show that Tyro3, but not Axl and Mer, mediates phosphorylation of FHKRL1 that is required for PS-mediated neuronal protection after tPA/NMDA-induced injury. Conclusions PS blocks the extrinsic apoptotic cascade through a novel mechanism mediated by Tyro3-dependent FKHRL1 phosphorylation which inhibits FasL-dependent caspase-8 activation and can control tPA-induced neurotoxicity associated with pathologic activation of NMDA receptors. The present findings should encourage future studies in animal stroke models to determine whether PS can increase the therapeutic window of tPA by reducing its post-ischemic neuronal toxicity.

Abstract Several myelin-associated factors that inhibit axon growth of mature neurons, including Nogo66, myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMgp), can associate with a common GPI-linked protein Nogo-66 receptor (NgR). Accumulating evidence suggests that myelin inhibitors also signal through unknown NgR-independent mechanisms. Here we show that MAG, a RGD tri-peptide containing protein, forms a complex with β1-integrin to mediate axonal growth cone turning responses of several neuronal types. Mutations that alter the RGD motif in MAG or inhibition of β1-integrin function, but not removal of NgRs, abolish these MAG-dependent events. In contrast, OMgp-induced repulsion is not affected by inhibition of b1-integrin function. We further show that MAG stimulates tyrosine phosphorylation of focal adhesion kinase (FAK), which in turn is required for MAG-induced growth cone turning. These studies identify β1-integrin as a specific mediator for MAG in growth cone turning responses, acting through FAK activation.