Neuropsychological consequences of cerebellar tumour resection in children: cerebellar cognitive affective syndrome in a paediatric population.

Acquired cerebellar lesions in adults have been shown to produce impairments in higher function as exemplified by the cerebellar cognitive affective syndrome. It is not yet known whether similar findings occur in children with acquired cerebellar lesions, and whether developmental factors influence their presentation. In studies to date, survivors of childhood cerebellar tumours who demonstrate long-term deficits in cognitive functions have undergone surgery as well as cranial irradiation or methotrexate treatment. Investigation of the effects of the cerebellar lesion independent of the known deleterious effects of these agents is important for understanding the role of the cerebellum in cognitive and affective development and for informing treatment and rehabilitation strategies. If the cerebellar contribution to cognition and affect is significant, then damage in childhood may influence a wide range of psychological processes, both as an immediate consequence and as these processes fail to develop normally later on. In this study we evaluated neuropsychological data in 19 children who underwent resection of cerebellar tumours but who received neither cranial irradiation nor methotrexate chemotherapy. Impairments were noted in executive function, including planning and sequencing, and in visual-spatial function, expressive language, verbal memory and modulation of affect. These deficits were common and in some cases could be dissociated from motor deficits. Lesions of the vermis in particular were associated with dysregulation of affect. Behavioural deficits were more apparent in older than younger children. These results reveal that clinically relevant neuropsychological changes may occur following cerebellar tumour resection in children. Age at the time of surgery and the site of the cerebellar lesion influence the neurobehavioural outcome. The results of the present study indicate that the cerebellar cognitive affective syndrome is evident in children as well as in adults, and they provide further clinical evidence that the cerebellum is an essential node in the distributed neural circuitry subserving higher-order behaviours.

In vivo proton magnetic resonance spectroscopy detection of human alcohol tolerance.

Alcohol tolerance was ascertained with in vivo proton magnetic resonance spectroscopy (MRS) in men who regularly consumed either large (10-20 drinks/week) or small (2-4 drinks/weeks) amounts of beverage alcohol. Brain ethanol concentrations were determined by MRS, and blood ethanol levels were measured by gas chromatography after controlled ethanol administration (0.8 g/kg). Brain-blood ethanol concentration ratios for heavy drinkers were significantly greater than ratios for occasional drinkers (P < 0.002). Inasmuch as ethanol tolerance covaries with the severity of dependence, MRS procedures may facilitate our understanding of alcohol tolerance and treatment of alcoholism.

Excitotoxic lesions of the rat entorhinal cortex. Effects of selective neuronal damage on acquisition and retention of a non-spatial reference memory task.

The neurotoxin N-methyl-D-aspartate was used to induce selective bilateral neuronal loss in the entorhinal cortex, in order to model one aspect of the neurodegeneration observed in Alzheimer's disease, Down's syndrome and aging. Lesioned, sham-lesioned and intact control rats learned a reference memory task involving a brightness discrimination for water reward. Rats were trained over 1 week until reaching criteria and tested for retention after a 10-day interval. Lesioned rats showed impaired retention compared to shams and controls, but were able to reacquire the task. Anatomical analysis confirmed excitotoxic lesions of the entorhinal cortex, and showed collateral sprouting of acetylcholinesterase-stained fibers into the outer molecular layer of the dentate gyrus, indicating denervation plasticity in the hippocampus. This functional anatomical study of the entorhinal cortex demonstrates the importance of the entorhinal cortex in memory retention, and raises the possibility that functional deficits in certain neurodegenerative diseases may be modeled by partial neuronal loss in the entorhinal cortex.