A case of possible paraneoplastic neurological syndrome presenting as multiple cranial nerve palsies associated with gallbladder cancer.

We report the case of a patient who had developed multiple cranial nerve palsies in the course of possible paraneoplastic neurological syndrome (PNS) associated with gallbladder cancer. Twelve days prior to visiting our hospital, a 69-year-old man began experiencing neurological symptoms, beginning with diplopia and progressing to ptosis of the left palpebra and subsequent complete closure of the eye within 8 days. Results of the initial medical examination indicated paresis of left oculomotor (III) and abducens (VI) nerves. MRI of the brain revealed no focal lesion that could have resulted in compression of the affected nerves, while further examination ruled out diabetes mellitus, infection, vasculitis, and other systemic autoimmune diseases as potential causes. Gadolinium-enhanced MRI revealed high intensity located in the oculomotor nerves, and steroid pulse therapy was performed based on the assumption of inflammatory diseases. Although slight improvement was observed with respect to the left extraocular paresis, subsequent emergence of bilateral facial nerve (VII) palsy, right abducens nerve palsy, and right oculomotor nerve palsy occurred in succession. PET/CT performed under suspicion of PNS, confirmed the presence of gallbladder cancer. Surgical extirpation of the cancer occurred 3 months following the appearance of left oculomotor paralysis, after which the patient underwent postoperative chemotherapy. All cranial nerve palsies resolved within 2 months after the operation, and both cancer and PNS have shown no recurrence for over 5 years. Pathological examination of the resected tumor revealed well-differentiated tubular adenocarcinoma showing some signs of epithelial-mesenchymal transition, typically an indicator of a poor prognosis. Nevertheless, lymph node metastasis did not progress beyond N2, and the cancer was completely removed by lymph node dissection. Therefore, the presence of multiple cranial palsies in this patient led to early detection of the asymptomatic gallbladder cancer and immediate administration of life-saving treatment.