A 69-year-old man presented with progressive nuchal pain and spastic gait 2 years after undergoing ventriculoperitoneal (VP) shunting for a pineal astrocytoma with obstructive hydrocephalus. The neurological manifestations were compatible with radiculomyelopathy caused by an upper cervical lesion. Magnetic resonance imaging showed an enhanced extramedullary mass lesion tightly constricting the upper cervical spinal cord. The pressure of the shunt system was 150 mmH₂O, and lumbar puncture revealed normal cerebrospinal fluid (CSF) pressure of 170 mmH₂O. After removal of the shunt system, the clinical symptoms and neuroradiological findings markedly improved. This symptomatic spinal mass lesion was thought to be formed secondary to chronic depletion of ventricular CSF through the VP shunt.