Multiple myeloma is a hematopoietic cancer that is multicentric and most commonly involves the spine. Multiple myeloma with extraosseous and intradural involvement is an extremely rare condition. Here we present a rare case of spinal multiple myeloma with intracranial and spinal intradural metastasis causing lumbar spinal nerve compression. We present a 60-year-old woman with progressive weakness of the lower limbs for several weeks. Spinal magnetic resonance imaging (MRI) showed a leptomeningeal tumor with nodularity spreading within the cauda equina. Examination of the brain using MRI showed a lytic skull bone lesion and leptomeningeal enhancement. The patient underwent L3-5 laminectomy. Immunohistological staining confirmed a diagnosis of multiple myeloma of the IgA kappa subtype. After surgery, the patient underwent chemotherapy and rehabilitation exercises. Multiple myeloma has a median survival of 2.5 years, while 75% of patients with spinal involvement die within 1 year of diagnosis. Unfortunately, our patient died 3 months after the diagnosis of multiple myeloma with spinal and intracranial involvement. Intracranial and spinal intradural multiple myeloma invasions are quitely rare. Spine biopsies and cerebrospinal fluid cytology can aid in the diagnosis. Early surgical decompression is necessary, especially when neurological deficits occur.