You see focal dystonia a fair amount.
I wish your Uncle well Drew.
Read some of this.
https://jnnp.bmj.com/content/86/6/667
points of interest. Google some words if you don’t know them, I did:
Indeed, in early life, there may even be unrecognised biological advantages of mutations associated with neurodegenerative disease in the post-reproductive years.42
Lou Gehrig, an American baseball celebrity from the 1930s, is inextricably associated with the disease in the USA. Various lifestyles, including unusual exercise regimes as in athletes,19 leisure-time activity,20 exposure to heavy work,21 soldiers in training,22 professional football players23 and handedness24 have all provided seductive associations of uncertain significance.
The link between ALS and FTD represents an extension of ALS as a motor system disease to the frontal and temporal lobes, themselves parts of the brain concerned with the expression of thought, planning, personality and speech, all aspects of brain function that are strictly ‘motor’ in a wider sense. It lends support to the view that ALS pathogenesis is in some way linked to the neocortical evolutionary development of the anterior motor brain.38
At present, we cannot identify the onset of the disease other than by the patient’s observations of the onset of focal weakness and wasting, or mental change, but these onset features are vague in their timing, and must represent much earlier changes that exist subclinically for many months or even years.64 The study of presymptomatic individuals carrying highly-penetrant ALS gene mutations is an important emerging initiative.65 Continuing discussion as to whether ALS begins in the motor cortex, as suggested by the finding of increased excitability (decreased inhibition) of the motor cortex prior to the onset of symptoms,66 or simultaneously in various sites in the motor system67 is consistent with concepts of spreading pathology in other neurodegenerative diseases, such as Parkinson’s.68 ,69 Consistent patterns of preferential muscle involvement in ALS, such as the lateral hand muscle wasting known as the ‘split hand’, have been linked to cortical representations associated with the development of the opposable thumb.70 The fasciculation so characteristic of ALS is itself evidence of the increased excitability at a lower motor neuronal level.71