Article
Impact of cerebellar nuclei on recovery of cerebellar symptoms after cerebellar surgery or cerebellar ischemia
Bedeutung der Kleinhirnkerne für die Rückbildung zerebellärer Symptome nach Operationen oder Ischämien des Kleinhirnes
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Published: | May 30, 2008 |
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Objective: The aim of the study was to examine somatotopy in the cerebellum and to evaluate a possible differential role of the cerebellar cortex and cerebellar nuclei in functional outcome.
Methods: Clinical findings and 3D MRI-based cerebellar lesion sites were compared in a group of 90 patients with acute and chronic focal cerebellar lesion caused by cerebellar tumours (47 patients) or by ischemic lesions (43 patients). Voxel-based lesion-symptom mapping (VLSM) was used to evaluate the relationship between regions of cerebellar injury and behavioural data gained by semi-quantitative clinical examination according to the International Cerebellar Ataxia Rating Scale (ICARS). The VLSM method is valuable for analyzing the relationship between brain lesion and behaviour performance on a voxel-by-voxel basis using individual but spatially normalized MRI.
Results: Only in patients with acute focal cerebellar lesions did VLSM analysis reveal a somatotopic representation in the superior cerebellar cortex. Lesions of vermal and paravermal lobules III-IV were correlated with lower limb ataxia, lesions of vermal, paravermal and hemispheral lobules IV - VI with upper limb ataxia, lesions of paravermal and hemispheral lobules V and VI with dysarthria and lesions of superior vermis with ataxia of posture and gait.
In patients with a chronic state of a disease, the strongest lesion-symptom correlations were found between cerebellar symptoms and lesions including the cerebellar nuclei: disorders in trunkal ataxia were correlated with lesions in the fastigial nucleus (NF), gait and posture with lesions in the NF and interposed nucleus (NI), upper and lower limb ataxia were correlated with lesions in the dentate nucleus (ND) and NI, speech disturbances with lesions in the ND. In patients with chronic focal lesions, no correlation was found between symptoms and cortical lesions.
Conclusions: These findings suggest that motor recovery following focal cerebellar lesions depends on the lesion site. Furthermore, it appears that permanent motor dysfunction is related to lesions affecting the cerebellar nuclei but not the cerebellar cortex, irrespective of the age of injury and the pathology.