Abstract
Background. Malignant lung cancer tumors easily metastasize to the brain and cause carcinomatous meningitis. In cases of carcinomatous meningitis, disseminated intradural extramedullary spinal cord metastasis spreading via the cerebrospinal fluid (CSF) from a brain tumor is an important condition that is called drop metastasis. Drop metastasis involves the gravity and flow of the CSF and affects sensory nerves. It is typical for such a patient to present with back and buttock pain, in addition to bladder and rectal disturbance. Case. A 60-year-old male (cT2aN2M0, stage IIIA) with lung adenocarcinoma and multiple brain metastases presented with spinal cord symptoms of cauda equina syndrome. Gadolinium (Gd)-enhanced spinal magnetic resonance imaging (MRI) showed the presence of an enhanced nodule at the S1/2 level and enhancement of the cauda equina. We diagnosed the patient with drop metastasis originating from brain metastasis. The risk factors for drop metastasis include the presence of brain tumors in the posterior fossa. The type of cancer and histological tumor classification are unimportant. Gd-enhanced spinal MRI (T1-weighted image) is useful for diagnosing drop metastasis. Conclusion. When lung cancer patients with brain metastasis in the posterior fossa present with neurological symptoms unlike those of brain metastasis, then Gd-enhanced spinal MRI should be performed as soon as possible.
