Dystonia Associated with pontomesencephalic lesions

Abstract

Secondary dystonia is well known subsequent to lesions of the basal ganglia or the thalamus. There is evidence that brainstem lesions may also be associated with dystonia, but little is known about pathoanatomical correlations. Here, we report on a series of four patients with acquired dystonia following brainstem lesions. There were no basal ganglia or thalamic lesions. Three patients suffered tegmental pontomesencephalic hemorrhage and one patient diffuse axonal injury secondary to severe craniocerebral trauma. Dystonia developed with a delay of 1 to 14 months, at a mean delay of 6 months. The patients' mean age at onset was 33 years (range 4-56 years). All patients presented with hemidystonia combined with cervical dystonia, and two patients had craniofacial dystonia in addition. Three patients had postural or kinetic tremors. Dystonia was persistent in three patients, and improved gradually in one. There was little response to medical treatment. One patient with hemidystonia combined with cervical dystonia improved after thalamotomy. Overall, the phenomenology of secondary dystonia due to pontomesencephalic lesions is similar to that caused by basal ganglia or thalamic lesions. Structures involved include the pontomesencephalic tegmentum and the superior cerebellar peduncles. Such lesions are often associated with fatal outcome. While delayed occurrence of severe brainstem dystonia appears to be rare, it is possible that mild manifestations of dystonia might be ignored or not be emphasized in the presence of other disabling deficits.

Current and emerging strategies for treatment of childhood dystonia

“…13–15 According to one model, dystonia arises from a net decrease in firing of inhibitory neurons projecting from the internal segment of globus pallidus to the ventral thalamus, causing an increase in the activity of excitatory thalamocortical projections to motor and premotor regions of the frontal cortex. 16 In some cases, however, no basal ganglia injury can be identified and recent evidence from both humans and animal models suggests that other brain areas including cerebellum, 17–20 brainstem, 21 or sensory cortex 22–23 can be causes of dystonia.…”

Evidence for Altered Basal Ganglia-Brainstem Connections in Cervical Dystonia

“…In addition to the basal ganglia, the pontine brainstem [1], [2], [3], [4], and cerebellum [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20] have been implicated in dystonia by numerous studies. As a synthesis of this literature and a number of other observations in dystonia, we recently hypothesized that the pallidal output neurons exhibiting extensive collateralization to the brainstem [21], [22], [23] are the neurons gating the functional system that is affected in dystonia.…”

Delayed hemiparkinsonism after closed head injury

“…In this patient, presynaptic dopaminergic imaging corroborated nigrostriatal denervation induced, presumably, by a previous traumatic hemorrhage. As a result, neuroimaging (Figures 1 and 2) showed specific features that validated the diagnosis of parkinsonism secondary to a traumatic etiology 2,3 . …”