Thesis defense Renee Lustenhouwer (Donders series 596)

8 March 2023

Promotor: prof. dr. B.G.M. van Engelen
Copromotor: dr. J.T. Groothuis, dr. I.G.M. Cameron, dr. R.C.G. Helmich

Recovery in Neuralgic Amyotrophy: an interplay between peripheral nerve damage, motor dysfunction, and the brain

Neuralgic amyotrophy (NA) is a common, yet underrecognized peripheral nerve disorder. In NA, acute autoimmune inflammation damages peripheral nerves, which causes muscle weakness. This often leads to motor problems, especially in the shoulder and arm. Many patients experience prolonged motor problems and other related residual complaints, such as functional impairment, pain and fatigue, even when the nerves and muscle strength recover. It is unclear why these complaints persist, and how to treat them best. It has been suggested that the brain may play a role in the persistence of motor problems, but this has never been investigated. This thesis set out to change that by investigating the following research questions:

1. Is the way the brain controls movement different in patients with NA compared to healthy people?

2. Can specific rehabilitation, which targets motor control, aid recovery after NA?

We answered these questions with functional MRI, motor imagery (=imagined movement), a randomized controlled trial and clinical outcome measures. First, we showed that the brain is indeed involved in NA: motor control in the brain was different for NA patients with residual complaints as compared to healthy volunteers. More specifically, NA patients had reduced brain activity in visuomotor brain areas during motor imagery of their affected arm. Second, we found that specific rehabilitation can aid clinical recovery: patients had better clinical outcome after specific rehabilitation compared to standard treatment. There was no difference in brain activity between the two treatment groups. Interestingly, patients’ brain activity increased in the same visuomotor brain areas that previously showed decreases, after both specific rehabilitation and the standard treatment. This shows that the brain is able to recover from altered motor control in NA. Our results form an important step towards improved rehabilitation for patients with nerve and muscle disorders such as NA.