- Last edited on June 1, 2023
Psychiatric Manifestations of Paraneoplastic Disorders
Primer
Paraneoplastic disorders can lead to severe psychiatric and behavioural symptoms. Rapid identification is required to ensure correct treatment and management to avoid misdiagnosis of a paraneoplastic neurologic disorder. Paraneoplastic neurological syndromes (PNS) are the immune-mediated effects of a remote cancer and are characterized by an autoantibody response against the antigens expressed by the tumour.
Autoantibodies
The autoantibody response can be psychiatric in nature, and includes:
- NMDAR-antibody encephalitis, associated with ovarian teratomas in younger women
- Ophelia syndrome, associated with surface-directed mGluR5-antibodies, seen in patients with Hodgkin’s lymphoma
- Anti-neuronal nuclear antibody-1 (ANNA-1), also known as Hu paraneoplastic encephalomyelitis, associated with small cell lung cancer in 75% of cases (other tumours include lung, prostate, breast, bladder, GI tract, ovary, neuroendocrine, unknown origin), most commonly in men.
- AMPA receptor antibodies, associated with lung, breast, thymus, ovarian tumours.
Paraneoplastic Limbic Encephalitis
Paraneoplastic limbic encephalitis (PLE) is a rare neurological syndrome associated with cancer, and selectively affects limbic system structures, including the hippocampus, hypothalamus, and amygdala.[1] It is usually associated with small cell lung cancer. The encephalitis is caused by an altered immunologic response to a malignancy that has antigens that resemble limbic antigens. The inflammatory response, however, occurs away from the original neoplasm site. [2]
Diagnosis
- Individuals with a personal or family cancer history, smoking history, should be worked up for paraneoplastic involvement.
- The most common tumours associated with paraneoplastic limbic encephalopathy are small cell lung cancer (SCLC) (about 75% of cases), germ-cell tumours (ovarian or testicular), thymoma, Hodgkin's lymphoma, and breast cancer.
- The most common symptoms are a subacute cognitive (primarily amnestic) syndrome.
- Depression, anxiety, personality changes, and emotional lability can often precede the cognitive impairment.
Investigations
- CSF evidence of inflammation
- Elevated tumor markers (e.g. - CEA, CA-125, PSA)