Time-dependent structural changes of the dentatothalamic pathway in children treated for posterior fossa tumor.
OBJECTIVE
Injury to the dentatothalamic pathway that originates in the cerebellum has been suggested as a mechanism for neurologic complications in children treated for posterior fossa tumors. We hypothesized that time-dependent changes occur in the dentatothalamic pathway.


METHODS
Diffusion tensor evaluation was performed in 14 children (median age, 4.1 years; age range, 1-20 years) who underwent serial MR imaging at 3T as part of routine follow-up after posterior fossa tumor resection with or without adjuvant therapy. Tensor metrics were obtained in the acute (≤1 week), subacute (1 to <6 months), and chronic (≥6 months) periods after surgery. We evaluated the following dentatothalamic constituents: bilateral dentate nuclei, cerebellar white matter, and superior cerebellar peduncles. Serial dentate nuclei volumes were also obtained and compared with the patient's baseline.


RESULTS
The most significant tensor changes to the superior cerebellar peduncles and cerebellar white matter occurred in the subacute period, regardless of the tumor pathology or therapy regimen, with signs of recovery in the chronic period. However, chronic volume loss and reduced mean diffusivity were observed in the dentate nuclei and did not reverse. This atrophy was associated with radiation therapy and symptoms of ataxia.


CONCLUSIONS
Longitudinal diffusion MR imaging in children treated for posterior fossa tumors showed time-dependent tensor changes in components of the dentatothalamic pathway that suggest evolution of structural damage with inflammation and recovery of tissue directionality. However, the dentate nuclei did not show tensor or volumetric recovery, suggesting that the injury may be chronic.
From the Departments of Neurology (S. Perreault, S. Partap).
S
S
Perreault
R M
RM
Lober
S
S
Cheshier
S
S
Partap
M S
MS
Edwards
K W
KW
Yeom
D000293:Adolescent; D001254:Astrocytoma / Q000601:surgery*; D002529:Cerebellar Nuclei / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D056324:Diffusion Tensor Imaging; D004806:Ependymoma / Q000601:surgery; D005260:Female; D006801:Humans; D007223:Infant; D015192:Infratentorial Neoplasms / Q000601:surgery*; D008137:Longitudinal Studies; D008297:Male; D008527:Medulloblastoma / Q000601:surgery; D009434:Neural Pathways / Q000473:pathology; D011183:Postoperative Complications / Q000473:pathology*; D012680:Sensitivity and Specificity; D013788:Thalamus / Q000473:pathology*; D013997:Time Factors; D055815:Young Adult