My Zebra for Your Horses: A Unique Case of Respiratory Failure in the Setting of Delayed Diagnosis of Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS)
Kennedy Gerber1, Reena Bastin1, Yaowaree Leavell2
1Oregon Health & Science University, 2Neurology, Oregon Health & Science University
Background:
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a rare progressive genetic disorder caused by homozygous SACS mutation. We present here a case remarkable for atypical severe respiratory failure and diagnostic momentum which resulted in a lifelong incorrect diagnosis of cerebral palsy (CP).
Design/Methods:
Case Description: A 49-year-old woman with a history of CP and spastic paraplegia was referred to neuromuscular clinic for functional decline and neuropathy. She reported childhood gait impairment with progressive decline to wheelchair use in her 20s. In her 40s she noted progressive numbness, ataxia, distal amyotrophy, dysarthria, and dyspnea. Magnetic resonance imaging (MRI) showed a classic ARSACS finding of superior cerebellar vermian atrophy misattributed by radiology to a chronic congenital infarct. Electromyography and nerve conduction studies (EMG/NCS) showed diffuse severe sensory neuropathy and mild distal neurogenic changes on the needle study. Pulmonary function testing revealed a functional vital capacity of 35 percent. Genetic testing revealed two pathogenic SACS mutations including a frameshift (c.10468dup) and a nonsense mutation (c.4298G>A).
Conclusions:
This case highlights two key points. First, diagnostic momentum and failure to apply Occam’s razor resulted in missed opportunities for a correct diagnosis. She was presumed to have baseline static CP, a cerebellar stroke, and an acute progressive sensory neuronopathy in lieu of a unifying hereditary disorder. The second is that respiratory failure in ARSACS is either rare or underreported. To our knowledge, this is only the second case of reported respiratory failure in ARSACS. Though reported lifespan is 50-60 years, the primary cause of death is not well described. We conclude first that it behooves providers to consider multisystem genetic syndromes as a unifying diagnosis in adults with multiple progressive complaints, and second that further research on prevalence of respiratory failure in ARSACS is needed to better understand potential contribution to demise and inform care.
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