Pathophysiology of akinetic movement disorders: a paradigm for studies in fibromyalgia?

Patients with fibromyalgia sometimes have sign of a movement disorder in addition to sensory disturbances sometimes similar as those found in akinetic syndromes. Akinesia is due to disturbances in the functions of the cortico-thalamo-nigro-striatal system and associated areas. The reason of this dysfunction in Parkinson's disease is a decreased nigral dopaminergic efferent innervation due to a neuronal degeneration in the pars compacta of the substantia nigra. Changes in other neurotransmitters, like GABA or serotonin, and in receptors and second messengers also occur, with additional modulation due to therapy. The aetiology of nigral malfunction is in only rarely known. Drugs and mutations of some genes are examples which give much insight in the pathogenesis of movement disorders in general. In other akinetic disorders, like multisystem atrophy, corticobasal ganglionic degeneration, and progressive supranuclear palsy, more complex patterns of degeneration have been found. This pathological anatomical disturbances have typical clinical effects which can be studied physiologically and with imaging in vivo. Since basal ganglia play also a role in pain, a comparative study of their involvement in movement disorders and nociception seems to be fruitful, especially in devising new therapeutic strategies.