Periodic alternating nystagmus (PAN) is defined as abnormal horizontal eye movements in periodically alternating directions, and the condition could be both congenital and acquired. Acquired PAN refers to a spontaneous horizontal nystagmus, present in central gaze, reversing in direction periodically. Acquired PAN has been reported to occur in association with a number of conditions, many of which involve the cerebellum.
Paraneoplastic neurological syndrome (PNS) is a rare syndrome representing the remote effects of a cancer, that is often associated with the presence of specific serum antibodies. PNS can affect the central, peripheral, and autonomic nervous systems at various levels. Clinically, it is characterized by subacute progression of neurological dysfunction and substantial refractoriness to therapies.
We report a case of PNS that presented with dizziness and light headedness. A woman in her 60s visited our otolaryngology department complaining of dizziness and light-headedness. At the first visit, she showed PAN in the front view in the sitting position and in the positional nystagmus test. She was hospitalized for gait disturbance.
A central lesion was suspected and MRI was performed, but there were no abnormalities. PNS was also suspected and whole-body CT was performed, which revealed no abnormalities. Under the suspicion of autoimmune cerebellar ataxia and acute cerebellitis, we started the patient on steroid pulse therapy. Although the PAN persisted, her dizziness improved, and she became able to walk and was discharged from the hospital. Three months after discharge from the hospital, she visited another hospital complaining of breathlessness on exertion, and a chest CT revealed an abnormal opacity with atelectasis in the right middle lobe of the lung. Detailed clinical examination and transbronchial lung biopsy at the respiratory department led to a diagnosis of small cell lung cancer, and the PAN was thought to be caused by paraneoplastic syndrome.
