Paraneoplastic Encephalomyelitis Clinical Presentation

Updated: Nov 16, 2021
  • Author: David S Liebeskind, MD, FAAN, FAHA, FANA; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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The neurologic manifestations of paraneoplastic encephalomyelitis (PEM) precede the diagnosis of cancer in 80% of cases. Typically, a subacute onset of neurologic symptoms is followed by progression over weeks to months, finally reaching a plateau of neurologic impairment. The clinical presentation reflects the distribution of this multifocal inflammatory condition. Specific clinical syndromes have been described, although considerable overlap exists.

  • Paraneoplastic limbic encephalitis presents with memory loss, personality changes, anxiety or depression, neuropsychiatric disturbances, partial or generalized seizures including status epilepticus, olfactory and gustatory hallucinations, sleep disturbances, and abnormalities in other homeostatic functions. [11]

  • Focal encephalitis may affect nonlimbic cortical regions, presenting with seizures or epilepsia partialis continua and focal neurologic disturbances such as aphasia, weakness, or numbness.

  • Brainstem encephalitis is present in one third of patients, presenting with oscillopsia, diplopia, facial numbness, dysarthria, hearing loss, and dysphagia.

  • Motor neuron dysfunction occurs in 20% of cases, presenting with asymmetric proximal weakness and neck weakness. Subsequent symptoms may include distal limb weakness and fasciculations.

  • Subacute sensory neuronopathy accompanies most cases of PEM, with absence of clinical manifestations in only 20-30% of cases. Symptoms include asymmetric focal numbness or paresthesias, typically involving the face, trunk, and proximal extremities. Burning or lancinating dysesthesias of all extremities may be noted at later stages.

  • Autonomic dysfunction is noted in one fourth of cases, presenting with postural hypotension, gastrointestinal disturbances, sweating abnormalities, urinary difficulties, impotence, sluggish pupils, and cardiovascular instability.

  • Lambert-Eaton myasthenic syndrome occurs in 10-16% of cases. [12]



Physical examination findings in paraneoplastic encephalomyelitis (PEM) assist in the localization of clinical symptoms and anatomical classification of specific paraneoplastic syndromes.

  • Paraneoplastic limbic encephalitis: Anterograde or retrograde amnesia and neuropsychiatric disturbances predominate, with altered levels of consciousness at later stages. Focal neurologic deficits also may be noted.

  • Focal encephalitis: Focal neurologic deficits occur and include aphasia and motor or sensory abnormalities. Epilepsia partialis continua or seizures may be evident. [13]

  • Brainstem encephalitis: Patients experience oscillopsia, diplopia, vertical and horizontal gaze abnormalities, facial numbness, dysarthria, hearing loss, and dysphagia.

  • Motor neuron dysfunction: Patients have neck flexor/extensor weakness, asymmetric limb weakness, fasciculations, atrophy, and a combination of upper and lower motor neuron signs.

  • Subacute sensory neuronopathy: Asymmetric focal sensory loss occurs on the face, trunk, and proximal extremities. Prominent sensory ataxia with vibratory and proprioceptive loss, pseudoathetosis, diminished reflexes, and gait abnormalities are noted.

  • Autonomic neuropathy: Patients have abnormal pupillary responses, postural hypotension, sweating abnormalities, neurogenic bladder, and respiratory or cardiovascular disturbances.



Smoking is a potential risk factor for paraneoplastic encephalomyelitis (PEM), as most cases are associated with small-cell lung cancer.

Family history of cancer is another risk factor.



Complications of paraneoplastic encephalomyelitis (PEM) include:

  • Severe neurologic disability or death

  • Infections

  • Deep venous thrombosis