The anatomical basis of upper limb dystonia: lesson from secondary cases

Abstract

Upper limb dystonia is a focal dystonia that may affect muscles in the arm, forearm and hand. The neuroanatomical substrates involved in upper limb dystonia are not fully understood. Traditionally, dysfunction of the basal ganglia is presumed to be the main cause of dystonia but a growing body of evidence suggests that a network of additional cortical and subcortical structures may be involved. To identify the brain regions that are affected in secondary upper limb dystonia may help to better understand the neuroanatomical basis of the condition. We considered only patients with focal upper limb dystonia associated with a single localized brain lesion. To identify these patients, we conducted a systematic review of the published literature as well as the medical records of 350 patients with adult-onset dystonia seen over past 15 years at our movement disorder clinic. The literature review revealed 36 articles describing 72 cases of focal upper limb dystonia associated with focal lesions. Among patients at our clinic, four had focal lesions on imaging studies. Lesions were found in multiple regions including thalamus (n = 39), basal ganglia (n = 17), cortex (n = 4), brainstem (n = 4), cerebellum (n = 1), and cervical spine (n = 7). Dystonic tremor was not associated with any particular site of lesion, whereas there was a trend for an inverse association between task specificity and thalamic involvement. These data in combination with functional imaging studies of idiopathic upper limb dystonia support a model in which a network of different regions plays a role in pathogenesis.

Cerebellum: An explanation for dystonia?

“…The relationship between cerebellar lesions and clinical manifestations of dystonia is supported by further observations in secondary BPS and OMD and in patients with upper-limb dystonia often ipsilateral to a focal cerebellar lesion [45–53]. Also, it has been recently observed patchy loss of cerebellar Purkinje cells in the cerebellum in a small sample patients with CD.…”

“…Several case series and case reports indicate a relationship between anatomical lesions of the cerebellum and dystonia [33–53], (Table 1). These studies indicate that majority of secondary cases of CD are associated structural lesions of the brainstem and cerebellum, with lesions in the cervical spinal cord and basal ganglia being observed less frequently [33–43].…”

The Anatomical Basis for Dystonia: The Motor Network Model

“… 79 , 80 In hemidystonia, the majority of lesions affected the basal ganglia, and particularly the putamen. Since then, multiple other studies have addressed cervical dystonia, 81 craniofacial dystonia, 82 limb dystonia, 83 and series with mixed populations. 84 , 85 A summary these studies indicates that the basal ganglia are not the only regions to be affected ( Table 2 ).…”

Idiopathic Non‐task‐Specific Upper Limb Dystonia, a Neglected Form of Dystonia

“…Non-task-specific ULD has often been considered to be secondary to lesions in the basal ganglia and other brain areas. 13 Knowledge about the clinical phenomenology of idiopathic non-task-specific ULD may be essential for design and implementation of future studies that aim to treat or modify disease course in those with idiopathic isolated ULD. We therefore performed a retrospective cross-sectional study to determine the frequency of nontask-specific ULD in a large cohort of Italian patients with adult-onset idiopathic dystonia and compared their main clinical and demographic features with those with a task-specific ULD (WC).…”