Injury of the lateral vestibulospinal tract in a patient with the lateral medullary syndrome: Case report.

RATIONALE: Lateral medullary syndrome is a central vestibular disorder characterized by vertigo and ataxia. We report on a patient with injury of the lateral vestibulospinal tract (VST) following lateral medullary syndrome, detected on diffusion tensor tractography (DTT). PATIENT CONCERNS: A 56-year-old male patient was diagnosed with lateral medullary syndrome due to an infarction in the posterior inferior cerebellar artery area. DIAGNOSES: Two weeks following the infarction, he was transferred to the rehabilitation department of the same university hospital with severe vertigo, ataxia (Berg balance scale: 16 point), and dysphasia. In contrast, he maintained good motor power and cognitive function (Mini-mental state test: 26 points). INTERVENTIONS: N/A OUTCOMES:: Both the patient's medial VSTs and left lateral VST were well-reconstructed. In contrast, the right lateral VST was not reconstructed. On DTT parameters of the VST, the patient's medial VSTs and left lateral VST did not differ significantly from the control subjects. LESSONS: An injury of the right lateral VST was demonstrated in a patient with lateral medullary syndrome. We believe that the result will be helpful in clinical management and research for patients with lateral medullary syndrome.

Cerebellar tract alterations in PLS and ALS.

The cerebellum shows neuropathological change in a number of neurodegenerative conditions where clinical involvement is not the primary feature, including amyotrophic lateral sclerosis (ALS). Whether these changes are associated with disruption to the direct cerebellar tract pathways to the motor cortex and spinal cord in ALS is uncertain. Diffusion tensor imaging was used to examine the integrity of two primary cerebellar pathways, the dentato-rubro-thalamo-cortical (DRTC) and spino-cerebellar (SC) tracts. ALS patients with an upper motor neuron (UMN)-predominant phenotype (n = 9), were matched to a group with the UMN-only condition primary lateral sclerosis (PLS, n = 10) and healthy controls (n = 17). Significant alterations across diffusion metrics in the DRTC proximal to the motor cortex were found in both patient groups. PLS patients were found to have an independent diffusion abnormality in the cerebellar region of the DRTC and SC tracts. Disruption to primary cerebellar tracts in PLS is therefore postulated, adding to other markers of its divergent pathogenesis from ALS.

The cerebellum and parietal cortex play a specific role in coordination: a PET study.

The synthesis of complex, coordinated movements from simple actions is an important aspect of motor control. Lesion studies have revealed specific brain areas, particularly the cerebellum, to be essential for a variety of coordinated movements, and lend support to the view that the cerebellum is engaged in the integration of simple movements into compound ones. A PET study was therefore conducted to show which brain areas were active specifically during the coordinated execution of an arm and finger movement to visual targets. A two-by-two factorial design was employed, in which subjects either made arm or finger movements alone, made coordinated arm-finger movements, or made no movements. Voxels were identified where activity was significantly greater during the execution of coordinated movements than when movements were made alone and in which this increased activity could not be accounted for simply by the additive effects of the activations for each movement in isolation. The behavioral results showed that subjects coordinated arm and finger movements well during coordination scans. Coordination-specific activations were found in left anterior lobe and bilaterally in the paramedian lobules of the cerebellum. These are known to receive forelimb-specific spinocerebellar proprioceptive inputs that may be related to multijoint movements. The same areas also receive corticocerebellar afference from motor areas that may convey efference copy information to the cerebellum. Coordination-specific activations were also seen in areas of the posterior parietal cortex. The results provide direct evidence in healthy human subjects of specific cerebellar engagement during the coordination of movement, over and above the control of constituent movements.