BACKGROUND: Cavernous malformations (CMs) are vascular malformations characterized by enlarged, thin-walled blood vessels composed of dysplastic endothelial cells and pericytes within a loose extracellular matrix. Endothelial cell dysplasia leads to increased permeability and portends an increased risk of hemorrhage within these malformations, and hemorrhage often manifests with acute-onset neurological deficits due to mass effect and irritation of surrounding neural tissue within the brain and spinal cord. OBSERVATIONS: A 5-month-old male presented with concern for possible tethered cord syndrome in the setting of forked gluteal cleft and lower extremity hyperreflexia. He was ultimately determined to have three intramedullary spinal CMs. These were resected with laminoplasty performed. Follow-up imaging demonstrated preservation of spinal alignment and no intraspinal lesion recurrence, with corresponding improvement in the patient's neurological strength examination despite some persistent motor developmental milestone delay. LESSONS: Hemorrhage and rehemorrhage rates of intramedullary spinal CMs are higher in the pediatric population than in the adult population. Hence, early resection of these lesions, when feasible, reduces the risk of long-term neurological deficit. Resection in infancy can be augmented by laminoplasty to preserve the posterior tension band within the spinal column, promote bony regrowth, and significantly reduce the risk of delayed deformity. https://thejns.org/doi/10.3171/CASE2557.