Secondary paroxysmal dyskinesia in multiple sclerosis: Clinical-radiological features and treatment. Case report of seven patients.

Secondary paroxysmal dyskinesias (SPDs) are short, episodic, and recurrent movement disorders, classically related to multiple sclerosis (MS). Carbamazepine is effective, but with risk of adverse reactions. We identified 7 patients with SPD among 457 MS patients (1.53%). SPD occurred in face ( n = 1), leg ( n = 2), or arm +leg ( n = 4) several times during the day. Magnetic resonance imaging (MRI) showed new or enhancing lesions in thalamus ( n = 1), mesencephalic tegmentum ( n = 1), and cerebellar peduncles ( n = 5). Patients were treated with clonazepam and then acetazolamide ( n = 1), acetazolamide ( n = 5), or levetiracetam ( n = 1) with response within hours (acetazolamide) to days (levetiracetam). No recurrences or adverse events were reported after a median follow-up of 33 months.

Deep brain stimulation in cluster headache: hypothalamus or midbrain tegmentum?

Functional and structural neuroimaging studies have provided pivotal insights into the pathophysiology of trigeminal autonomic cephalalgias (TACs), particularly cluster headache (CH). Functional imaging studies using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) in TACs have reported activation of the posterior hypothalamus. A structural neuroimaging study using voxel-based morphometry in CH reported increased volume of the hypothalamic gray, although another larger study failed to reproduce this finding. These studies in CH prompted the use of stereotactic stimulation of the target point identified by functional and structural neuroimaging. The precise anatomical localization of the deep brain stimulation (DBS) target places it at the midbrain tegmentum rather than the posterior hypothalamus. A comparison of the PET and fMRI studies in TACs reveals that the diencephalic/mesencephalic activation is more posteroinferior in the PET studies, straddling the hypothalamus and midbrain tegmentum, whereas the activation is centered on the hypothalamus in the higher spatial resolution fMRI studies. To optimize the outcomes from DBS, it is likely that patients will need to be studied individually using functional imaging techniques that have high spatial and temporal resolution to enable targeting of the appropriate locus with stereotactic stimulation.

Dystonia associated with pontomesencephalic lesions.

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.

The metabolic topography of posthypoxic myoclonus.

Posthypoxic myoclonus (PHM) is a syndrome of action and intention myoclonus that occurs in some patients who survive a cardiac arrest. Using PET and statistical parametric mapping, the authors observed a significant bilateral increase in glucose metabolism in the ventrolateral thalamus and pontine tegmentum in patients relative to controls. Interventions such as deep brain stimulation that interrupt networks that involve these structures may be useful in patients with severe PHM.

Regional cerebral blood flow in fibromyalgia: single-photon-emission computed tomography evidence of reduction in the pontine tegmentum and thalami.

OBJECTIVE: To determine whether regional cerebral blood flow (rCBF) is abnormal in any cerebral structure of women with fibromyalgia (FM), following a report that rCBF is reduced in the thalami and heads of caudate nuclei in FM. METHODS: Seventeen women with FM and 22 healthy women had a resting single-photon-emission computed tomography (SPECT) brain scan to assess rCBF and a T1-weighted magnetic resonance imaging (MRI) scan to enable precise anatomic localization. Additionally, all participants underwent 2 manual tender point examinations and completed a set of questionnaires evaluating clinical features. SPECT scans were analyzed for differences in rCBF between groups using statistical parametric mapping (SPM) and regions of interest (ROIs) manually drawn on coregistered MRI. RESULTS: Compared with control subjects, the rCBF in FM patients was significantly reduced in the right thalamus (P = 0.006), but not in the left thalamus or head of either caudate nucleus. SPM analysis indicated a statistically significant reduction in rCBF in the inferior pontine tegmentum (corrected P = 0.006 at the cluster level and corrected P = 0.023 for voxel of maximal significance), with consistent findings from ROI analysis (P = 0.003). SPM also detected a reduction in rCBF on the perimeter of the right lentiform nucleus. No correlations were found with clinical features or indices of pain threshold. CONCLUSION: Our finding of a reduction in thalamic rCBF is consistent with findings of functional brain imaging studies of other chronic clinical pain syndromes, while our finding of reduced pontine tegmental rCBF is new. The pathophysiologic significance of these changes in FM remains to be elucidated.