A 66-year-old right-handed lady was diagnosed with Huntington's disease (HD)-like 4 disorder due to SCA17 mutation (43 CAG/CAA-repeats in TBP gene) at the age of 54. Disease onset was characterised by gait imbalance, falls and fidgetiness. Over the years, a progressive mood decline and cognitive deterioration accompanied the motor symptomatology. Concerning her family history, three of her siblings were similarly affected by generalised involuntary movements.
On examination, she presented with motor impersistence on eye-movement assessment and tongue protrusion. Involuntary choreic movements affected the face and limbs. The gait was broad-based. Severity of ataxia was rated with the SARA scale (25/40). Gait (4/8), stance (4/6) and speech (4/6) were significantly impaired; finger-chase test, nose-finger test, fast alternating movements and heel-shin test were as well severely affected (3/4); on sitting, there were slight difficulties with intermittent sway (1/4).
Brain MRI disclosed a severe cerebellar volume loss. On the neuropsychological assessment, the most notable finding was a significant executive dysfunction. All the other domains assessed, including memory (MMSE 21/30), visual perceptual skills, reading, naming, praxis and speed of information processing, were equally impaired.
In the last 2 years, her husband reported the development of self-injurious behaviour, namely scratching of the skin resulting in severe excoriations of the chest, arms and lower limbs. She denied itchiness. According to the partner, the skin scratching seemed to be preceded by an urge of action followed by a subsequent relaxation.
This lady noticed for the first time a turning of the legs and curling of the hands at the age of 48. She had a family history of depression, anxiety and dementia, and reported to suffer from low mood too. On examination, she presented with generalised chorea and some difficulty with tandem gait. There were skin wounds in the upper limbs caused by repetitive self-injuring acts. Nevertheless, she was not able to report whether inner pressure or relief related to the skin scratching was experienced. Attention, concentration and memory were mildly impaired. She was admitted to hospital for further investigation. Brain MRI was normal, while the genetic screening revealed an abnormally expanded 50 CAG/CAA-repeats in TBP gene and a diagnosis of SCA17 was then confirmed.