Paraneoplastic neurologic syndromes are heterogenous disorders that can occur in the setting of various types of cancer (1). Paraneoplastic neurologic disorders are commonly caused by immune-mediated mechanisms triggered by an underlying tumor and have to be distinguished from neurological symptoms related to direct tumor invasion, infection, vasculopathy, ischemia, metabolic disturbances, or treatment-related toxicities.
Abnormal antibody or T-cell-mediated responses can target any part of the central, peripheral or autonomic nervous system to cause a diverse range of neurological symptoms. In general, the incidence of paraneoplastic syndromes is less than 1% in the general cancer population, but may be more frequently seen in specific types of cancer, such as small cell lung cancer (SCLC), cancers of the ovary and breast, and thymoma.
The diagnosis of a paraneoplastic neurologic syndrome is primarily clinical. Classical paraneoplastic syndromes (Table 65-1) may develop before the diagnosis of cancer, in a patient with known cancer, or in a patient considered to be in cancer remission. While an extensive search for an underlying tumor is warranted in classical paraneoplastic syndromes, such as paraneoplastic cerebellar degeneration (PCD) or Lambert-Eaton myasthenic syndrome, it may be noteworthy that several neurologic syndromes designated as "paraneoplastic" may also be seen in non-neoplastic autoimmune diseases.
TABLE 65-1CLASSICAL PARANEOPLASTIC SYNDROMES OF THE NERVOUS SYSTEM ||Download (.pdf) TABLE 65-1 CLASSICAL PARANEOPLASTIC SYNDROMES OF THE NERVOUS SYSTEM
|Syndrome ||Symptoms ||Common Antibodies |
|Paraneoplastic cerebellar degeneration ||Rapid onset (days to weeks) of truncal and appendicular ataxia, imbalance, dizziness, nausea, diplopia, dysphagia, nystagmus ||Anti-Yo, anti-Hu, anti-VGCC, anti-CV2/CRMP5, anti-Ma2, anti-Ri, anti-Tr, anti-GAD, anti-mGluR1 |
|Paraneoplastic encephalomyelitis/ limbic encephalitis ||Subacute onset of mental status changes, memory deficits, behavioral changes, emotional lability, insomnia, seizures ||Anti-Hu, anti-Ma2, anti-CV2/CRMP5, anti-VGKC, anti-Ri, anti-amphiphysin, anti-GABABR, anti-AMPAR, anti-GAD |
|Paraneoplastic opsoclonus-myoclonus ||Large amplitude ocular saccades (opsoclonus) and other abnormal eye movements alone or in combination with myoclonus; can be associated with hypotonia, irritability, ataxia and encephalopathy ||Anti-Hu, anti-Ri, anti-Ma2, anti-amphiphysin |
|Cancer associated retinopathy ||Photosensitivity and visual loss; may start in one eye and frequently progresses to involve both eyes; bilateral blindness may develop over the course of several months ||Anti-recoverin |
|Melanoma associated retinopathy ||Rapid onset of visual disturbances with flickering, night blindness and peripheral field visual loss; usually does not progress to full blindness ||Anti-bipolar cells of the retina |
|Stiff person syndrome ||Axial stiffness, spine deformities, painful muscle spasms triggered by sudden movements and noise or emotional upset ||Anti-amphiphysin, anti-GAD |
|Dorsal root ganglionitis (subacute sensory neuronopathy) ||Abnormal sensations affecting pain, temperature, touch and proprioception ||Anti-Hu, anti-CV2/CRMP5, anti-amphiphysin |
|Sensorimotor polyneuropathy ||Motor and sensory deficits, occasionally associated with tremors and gait disorder; may be acute or chronic ||Anti-MAG, anti-Hu, anti-CV2/CRMP5, anti-amphiphysin |
|Autonomic neuropathy ||Orthostatic hypotension, arrhythmias, impotence, intestinal pseudo-obstruction ||Anti-Hu, anti-gAChR |
|Neuromyotonia ||Fasciculations, delayed muscle relaxation, weakness ||Anti-VGKC |
|Lambert Eaton myasthenic syndrome ||Proximal muscle weakness, typically improving with repetitive action ||Anti-VGCC |
Since paraneoplastic syndromes often herald the ...