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Follow up

Follow up includes a clinical examination and completion of cranio-spinal MRI every four months during the the first two years, every six months the following two years, and then once a year till five years (69). It is particularly important for younger patients treated with chemotherapy alone, as relapses can be effectively treated with chemotherapy and radiation (see above). In older children, aimed at improving the prognosis of relapses by earlier treatments whose effectiveness should be evaluated.

Sequallae

1. Neuro cognitives Sequellae

The different factors influencing the neuro cognitives sequelae are: the age at diagnosis, primary tumor (metastastatic potential, hydrocephalus), especially if late diagnosis, surgery (vermian incision) in case of complications, radiotherapy (whose effects are dose-dependent), chemotherapy, parental and school environment, and the quality of care of these sequelae.

The intellectual sequelae are much more pronounced if the age at diagnosis is early (45). Before diagnosis, intellectual sequelae can result from brain damage due to hydrocephalus, and can be more significant with late diagnosis. They can also the result from:

• trauma due to the placement of a CSF diversion device, surgery, the possibility of postoperative complications such as meningitis or shunt infection as the cerebellum plays a vital rule in the development of cognitive function. (32, 33, 36)
• Chemotherapy affection of the senses (deafness due to the use of platinum compounds) or related encephalopathy especially when combined with radiation (16, 17)
• Radiotherapy (28, 29) which is the leading cause of intellectual sequelae. Batteries of the various tests used enable the identification of abnormalities of attention, memory, coordination, speed fine motor, visual motor process, mathematics and and spatial relations (35). The drop in IQ, though it does not fully reflect the intellectual adaptability, is the most commonly used parameter to report impaired intellectual performance (29).
• A decrease in IQ even if it does not fully reflect intellectual adaptability, is the most commonly used parameter to report impaired intellectual performance (29). It can occur in the first year following radiation therapy and continue over time, on average 5 to 10 years. Thus, in the study of Hoppe-Hirsh et al., as a result of radiotherapy at a prophylactic dose 35 Gy on the brain and a curative of 55 Gy for the posterior fossa, an IQ less than 80 is observed in 42 % and 85% respectively at 5 years and 10 years of diagnosis (32).
• - Intellectual impairment is more significant when irradiation occurs early in life (45) which led to postponement of irradiation in children aged less than five years. In a study on the longitudinal follow of IQ, children older than 7 years at the time of irradiation had a significantly lower IQ at the end of study than for younger children and children with initial IQ higher than 100 were those whose with the greatest drop in IQ falls (56). Intellectual impairment varies directly with the volume and dose of irradiation (whole posterior versus tumor bed ) (29, 33, 64). Thus, in the study by Mulhern et al., Children who received prophylactic irradiation at a dose of 35 Gy had a lower average IQ score respectively of 8 and 10 percentage points compared to those who received the dose of 24 Gy (45). No correlation has been observed between the evolution of the IQ and the lesions that may appear on MRI (21).

2. Endocrine Sequellae

An impairment in the endocrine fucntion is observed in more than 50% of cases. Impaired growth hormone secretion (GH) is the leading cause and the ealiest of endocrine sequelae. Following irradiation of the hypothalamic-pituitary axis growth retardation can be detected at the third month (17). Abnormal response to GH stimulation test and / or a decrease in the growth rate can be observed at doses of 29 Gy or 18 Gy in the case of craniospinal irradiation (26). Combined chemotherapy is also implicated in the severity of short stature (49).

The occurrence of early puberty may pose the diagnostic problem of a normal growth velocity due to secretion of gonadotropins in children with impaired GH secretion which leads to a final decrease in height due to premature epiphyseal fusion. Treatment with GH is indicated there exists a complete deficit objectified by provocation tests. However, this treatment does not achieve a total recovery of height in all cases. Also, spinal irradiation causes a decrease in the growth of the spinal column independent of any anomaly of the GH due to the irradiation of the vertebral growth cartilage. This abnormal vertebral growth is more significant if irradiation occured at an early age, and can lead to a deficit of 9 cm of height in the trunk (64). GH deficiency may also be responsible for changes in body composition and increased cardiovascular risk (30). The risk of increasing the incidence of tumor recurrence has so far not been reported (53).

Other neuroendocrine deficits may occur. The most common abnormality then is hypothyroidism which occurs in over half the cases related to the irradiation of the thyroid itself and the hypothalamic pituitary axis (30). Hypothyroidism is dose-dependent and can occur at a dose from 25 Gy to the neck. Due to the oncological risk of prolonged stimulation of the thyroid by TSH following thyroid irradiation, annual monitoring is necessary and an eventual treatment with thyroxine. Puberty may occur prematurely, due to prolonged hydrocephalus and especially from prophylactic brain irradiation (48); late occurrence is very rare and usually normally. Abnormalities of gonadotropins or cortico-adrenal axis are rare.

3. Neurosensorial Sequellae

The most common is a decrease in hearing related with the use of platinum compounds, but can also be due to radiotherapy. It is dose-dependent and is severe in about 10% of cases (39). Neurological sequelae are primarily cerebellar and tend to improve over time (52).

4. Quality of life

Very few studies have reported the quality of life of patients treated during their childhood for medulloblastoma. In the most documented study involving 342 adults treated during childhood between 1945 and 1974, having lived in more than 5 years from treatment till the age of 21, and compared with 479 members of their siblings, those treated for medulloblastoma had significantly more health problems, more physical and / or intellectual incapacity to work and drive (44). In addition, adults who had been treated for a brain tumor in childhood (especially a MB) had a greater risk of suicidal thoughts (7).

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