A mobile neurinoma arising from a redundant nerve root of the cauda equina is reported. The abnormal length of the nerve root allowed the neoplasm to move in the cranio-caudal direction along two segments of the spine.

The ultrastructural appearance of two chondroblastoma were examined by scanning and transmission electron microscopy. The polygonal basal cells, with a scanty pericellular matrix, show a poorly developed endoplasmic reticulum and many Golgi bodies. The highly differentiated chondroid cells are assembled in isogenous clusters and show intracytoplasmic inclusions of glycogen and lipids, numerous mitochondria and superficial secretion vesicles arising from a well developed rough endoplasmic reticulum. Clusters of crystals, in close contact with the matrix collagen fibres are found near to the tumour cells. These ultrastructural characteristics, together with the basal undifferentiated cells that proliferate and differentiate into cartilaginous tissue, distinguish this neoplasm from chondroma, mesenchymal chondrosarcoma and chondromyxoid fibroma and confirm its chondroid origin.

Notwithstanding the advent of magnetic resonance imaging (MRI), some etiologies of piriformis syndrome continue to remain obscure and elude this investigation. We report a case characterized by a long history and a clinical picture both typical of piriformis syndrome, caused by hypertrophy of the piriformis muscle clearly demonstrated at MRI. At surgery, we also found a likely neurovascular conflict not documented by MRI, consisting of an intimate relation between the sciatic nerve and the inferior gluteal artery.Following the surgical correction of both possible sources of pain, the patient experienced a slowly progressive relief of the sciatica.

Seven patients with redundant roots of the cauda equina were followed 2 1/2-10 years after surgical decompression. Improvement of signs and symptoms occurred in all patients. However, none of them was neurologically intact at the time of the last physical examination, although persistence of minimal neurological signs and/or occasional pain did not prevent a useful occupational activity.

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