Cerebral arteriovenous malformations (AVMs) present a challenge to diagnose in children with developmental disability, because of the overlap in behavioral symptoms and neurologic manifestations. They have been very rarely reported in conjunction with autism spectrum disorder. This case involves a 13 year old male with a history of autism spectrum disorder and significant behavioral issues diagnosed with a thalamic AVM following lateralizing neurologic symptoms. Despite radiosurgical treatment, hemorrhage followed consequently causing extensive neurologic injury and death. This case emphasizes the need for close follow up and coordination within a medical home for children with developmental disabilities. A multidisciplinary team approach is ideal to allow detection of subtle neurologic changes over time that may be masked as behavioral difficulties.