Dermatome variations in patients with transitional vertebrae.

OBJECTIVES To test whether the position of lumbosacral dermatomes varies in the presence of transitional vertebrae. MATERIAL AND METHODS Fifty consecutive male patients were tested for thoracolumbar and lumbosacral transitional vertebrae by radiography and for the position of the dermatome gap between the lumbar dermatomes L1, L2, L3, and the sacral dermatomes S2 and S3. The dermatome gap was documented with the use of the cremasteric reflex, the receptive field of which ends sharply at the gap which allows its delineation. RESULTS Thirty two of 50 patients had a normal thoracolumbosacral spinal configuration, 10 patients had transitional vertebrae. The patients with a cranial displacement of the thoracolumbar or lumbosacral vertebral transition showed a dermatome gap which lay significantly more ventrally than in the patients with a normal spinal configuration. CONCLUSION The finding supports the notion of a variant position of lumbosacral dermatomes in the presence of transitional vertebrae in males.