F09 Huntington disease and amyotrophic lateral sclerosis: a case study

Background Huntington disease (HD) and amyotrophic lateral sclerosis (ALS) are clinically distinct neurodegenerative disorders; however, there are reports of the coexistence of the two conditions. This has led to a debate about whether these cases are a coincidental occurrence of both diseases or whether an expanded HD allele could be a risk factor for developing ALS in a rare subset of HD patients. Case history We report a male patient with onset of HD motor symptoms at 64 years of age who then developed ALS at 74 years of age. The patient has multiple family members with HD including his father who developed symptoms in his early 70’s. The patient had predictive testing for HD in 1998 which revealed an expanded HTT allele of 39 CAG repeats. He has no family history of ALS. The patient reported HD symptoms began about 8 years ago and recently some mild cognitive decline. A motor exam in 2014 found mild chorea in all extremities, head and neck. Swallowing difficulties, worsening chorea and balance were noted in 2016. By November 2017, the patient presented with rapidly progressing proximal weakness in the arms and legs, as well as, distal weakness and atrophy in the right hand intrinsics and weakness at both ankle dorsiflexors. The degree of weakness and wasting was higher than typically seen in HD. Further examination found fasciculation in the distal hands. Needle EMG examination showed mild denervation in the right C5/C6 myotome and severe denervation in the right tibialis anterior. In addition, there was evidence of wide spread denervation in the thoracic paraspinal muscles in keeping with active and chronic motor neuron disease. Conclusion We present a patient with early manifest HD who developed ALS to contribute to the literature in this area.