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[Spondylolysis in the developmental stage: diagnostic contribution of MRI].

PURPOSE
To assess the value of MR imaging in demonstrating ongoing spondylolysis in adolescents.


METHODS
MRI was performed in 9 juvenile patients (3 female, 6 male aged 8-16 years; mean 12.5 y) with pain during hyperextension. In 6 patients a CT scan and in 5 a plain film was available.


RESULTS
In all patients bone marrow edema was found in the pars interarticularis and the pedicle, which was bilateral in 4 patients. In 7/9 cases the L5 vertebra was affected, in 2/9 cases spondylolysis was found in L4. In 3 cases the edema reached the middle third of the vertebral body and a tumor was suspected. In all CT scans a bilateral incomplete or complete cleft in the pars inter-articularis was found. In 4/6 CT-scans a sclerosis was seen in the area of the bone marrow edema. Only in 1/5 plain films was there a suspicion for a spondylolysis, four examinations were completely normal.


CONCLUSIONS
To eliminate underlying causal conditions of spondylolysis and to install specific therapy, early diagnosis is mandatory. MR imaging should be the first and only imaging modality in young patients with low back pain during and after exercise and pain with hyperextension. Bone scans and CT scans should be avoided due to irradiation, plain films usually do not reveal pathological findings in developing sponylolysis.