Our patient is a 31-year-old male who presented with complaints of rapidly progressive lower extremity weakness, gait abnormality and diarrhea. He was referred to our center for possible diagnosis of amyotrophic lateral sclerosis (ALS). By the time of our initial evaluation, he was wheelchair bound with chronic diarrhea, and he was beginning to show signs of cognitive decline. Examination showed cognitive slowing, lower extremity weakness, diffuse hyperreflexia, and both axial and appendicular cerebellar signs. There was no corneal clouding or xanthomas. EDX exam showed diffusely slowed velocities at non-entrapment sites and prolonged F-wave latencies. EMG showed no evidence of active or chronic neurogenic changes. MRI of the brain was revealing for FLAIR hyperintensities in the bilateral dentate nuclei and posterior limbs of the internal capsule with extension into the corticospinal tracts and cerebral peduncles concerning for ALS or metabolic disorder. Given chronic diarrhea and MRI findings with dentate nucleus hyper-intensities, CTX was suspected and was confirmed by biochemical testing. We subsequently started Chenodeoxycholic Acid.