Paraneoplastic Neurologic Syndromes: Rare But More Common Than Expected Nine Cases with a Literature Review

Paraneoplastic neurologic syndromes (PNS) are rare disorders, which are remote effects of cancer that are not caused by the tumor, its metastasis or side effects of treatment. We had nine patients with PNS; two of our patients had limbic encephalitis, but one had autoimmune limbic encephalitis with no malignancy; two patients had subacute cerebellar degeneration; three had Stiff-person syndrome; one had Lambert-Eaton myasthenic syndrome; and the remaining patient had sensory neuronopathy. In most patients, the neurologic disorder develops before the cancer becomes clinically overt and the patient is referred to a neurologist. Five of our patients’ malignancies had been diagnosed in our clinic after their neurologic symptoms became overt. PNS are more common than expected and neurologists should be aware of the variety of the clinical presentations of these syndromes. When physicians suspect PNS, cancer screening should be conducted. The screening must continue even if the results are negative.