Low cerebellar vermis volumes and impaired neuropsychologic performance in children treated for brain tumors and leukemia

Abstract

Background and purpose: Injury of the cerebellar vermis may occur in children with brain malignancies. Because the vermis is involved in motor and cognitive functioning, the goal of this prospective longitudinal study was to evaluate treatment-related changes in vermal volumes and neuropsychologic performance in children receiving brain radiation of the cerebellum.

Materials and methods: Ten patients (mean age, 11.6 years) and 10 healthy children (mean age, 12.1 years) were examined. Lobar vermal volumes and performance on neuropsychologic tests evaluating motor, visual, verbal, attention, memory, and executive functions were assessed at baseline and at 6-month follow-up visits.

Results: At baseline, lower mean vermal volumes and impaired performance on visual-spatial and fine-motor tasks were detected in patients. At 6-month follow-up, further decrease in vermal volumes was detected only in patients with medulloblastoma, who received the largest radiation doses to the entire vermis. The volume decrease was not associated with reduction in neuropsychologic performance compared with baseline. At 6-month follow-up, data from all subjects revealed an association between smaller vermal volumes and slower fine-motor speed and lower visual-spatial skills.

Conclusions: Reduced brain-tissue volumes following radiation have been reported previously in pediatric patients. In this study, lower vermal volumes were detected even earlier, before radiation treatment was initiated or completed. Six months postradiation, vermal volume decreases detected in patients with medulloblastoma were not accompanied by declines in already poor neuropsychologic performance. In addition to radiation, the presence of brain malignancies and preradiation treatment may be important factors affecting cerebellar vermis tissue.

Fig 1.

T1-weighted midsagittal images obtained at baseline visit in an 8.6-year old healthy girl (A), a 10.2-year old boy with ALL (B), and an 8.5-year old girl diagnosed with medulloblastoma (C, surgical resection included the posterior vermis).

Fig 2.

Relative lobar vermal volumes in healthy children and patients with brain malignancies. Patients tended to have lower relative vermal volumes even before the start of the radiation treatment. The volumes of the posterior vermis, lobules VIII-X, were the lowest in 3 patients with medulloblastoma treated by surgical resection, which involved removing parts of cerebellar tissue. The lines connect data from individual subjects; asterisks indicate patients with medulloblastoma.

Fig 3.

Relationship between percentage changes in relative lobar vermal volumes and corresponding radiation doses. Results of linear regression analyses are shown. The decrease in anterior and posterior vermal volumes was the highest in the patients with medulloblastoma (labeled with asterisks) who were treated with the highest radiation doses to the vermis (in addition to surgery and chemotherapy).

Fig 4.

Standard scores of the WJ-III Visual Matching test and z scores of the Purdue Pegboard both hands, right hand, and left hand tests in healthy children and patients with brain malignancies. Low test scores in patients indicate impairment in visual selective attention, processing speed, and manipulative dexterity. The lines connect data from individual subjects. Asterisks indicate patients with medulloblastoma.

Fig 5.

Relationship between z scores of the Purdue Pegboard Tests and total relative vermal volumes at the 6-month follow-up visit. Results of linear regression analyses are presented. Low vermal volumes in patients with medulloblastoma (labeled with asterisks) were associated with poor performance on the Purdue Pegboard Tests. Filled circles indicate patients; open circles indicate controls.