Thoracic outlet syndrome (TOS) is a condition that results from the compression of neurovascular structures as they exit the thorax. Arterial ischemic stroke can occur in TOS due to retrograde embolism from the subclavian artery. We describe a 15-year-old girl who presented with left hemiplegia after 2 weeks of right arm numbness and tingling. Imaging showed an acute ischemic stroke due to a right middle cerebral artery occlusion. She was treated with intravenous tissue plasminogen activator at 1.3 h and mechanical thrombectomy at 2.4 h with successful recanalization. Review of her neck computed tomography angiogram suggested a right subclavian artery aneurysm, and upper-extremity imaging also demonstrated distal thrombosis and fusion of right first and second ribs, which was consistent with thoracic outlet syndrome. Three days later, she underwent a right subclavian artery aneurysm repair, right brachial and ulnar artery thrombectomy, and first rib resection. Three months later, she demonstrated good neurologic recovery. TOS is an uncommon cause of stroke in children, which may be heralded by upper-extremity symptoms. Interventionalists should be aware of the possibility of vascular anomalies in children; however, this finding does not exclude the possibility of acute stroke intervention.

ObjectiveIllustrate that some neuroinflammatory diseases may respond best to antiproliferative therapies rather than immunomodulatory therapies.BackgroundGenomics are increasingly employed in the diagnostic armamentarium of refractory neuro-inflammatory diseases. Metagenomic next-generation sequencing is used to detect pathogens and germline genetic testing is used to detect inborn errors of the immune system. Genetic testing of tissue can identify somatic mutations for targeted treatment. MEK-inhibitors are an emerging treatment for RAS/MAPK pathway mutated diseases which include some neuro-inflammatory mimics like neuro-histiocytoses.Design/MethodsNA.ResultsPreviously healthy 12-year-old girl presented with 1 month of diplopia and headaches. Her brother has clinically diagnosed NF1 (café-au-lait macules, cutaneous neurofibromas). Exam notable for right third nerve palsy. MRI showed T2/FLAIR hyperintense lesions of the right temporal lobe, basal ganglia, and cervical through thoracic cord, nodular leptomeningeal enhancement along the entire spinal cord, and right middle cerebral artery vessel wall enhancement. CSF: WBC 6/mm3(62% lymphocytes 37% monocytes), protein 133 mg/dL. She improved with pulse methylprednisolone and maintenance steroids. At 5 months, she developed malignant elevated intracranial pressure with CSF OP >50 cm water, bradycardia, and encephalopathy requiring weekly LPs. Brain biopsy showed astrocytic and microglial activation without significant inflammation. No histiocytes were noted. There was no evidence of neoplasia or infection. She was tried on anakinra. At 6 months, she developed left third nerve palsy and seizures. For weeks, she required daily LPs for intracranial hypertension despite placement of ventriculoperitoneal shunt. Additional treatments included infliximab, steroids, and siltuximab. NGS from brain biopsy identified 2 NF1 mutations (nonsense, splicing). Allele fractions: 6% and 9%. Her mental status and need for frequent LP improved dramatically with trametinib.ConclusionsThis case illustrates the importance of considering somatic genomic testing of neural tissue even when the neuropathology is not suggestive of a malignancy or histiocytosis as this can inform newer molecularly targeted therapeutic options.