Brainstem encephalitis
Clinical features
Brainstem encephalitis may occur associated with different tumors in
all of them the common pathological hall mark is neuronal loss with
perivascular and intraparenquimatous inflammatory infiltrates. In patients
with small-cell lung cancer (SCLC) brainstem encephalitis usually present
with involvement of other areas of the nervous system (encephalomyelitis).
The symptoms of brainstem encephalitis reflect the
predominant involvement of the floor of the fourth ventricle and the
inferior olives and include vertigo, nystagmus, oscillopsia, ataxia,
diplopia, dysarthria, and dysphagia. Some patients develop respiratory
insufficiency that requires assisted ventilation. CSF studies may show
pleocytosis and elevated protein levels. MRI brain scans are normal.
A second brainstem encephalitis is associated with breast or gynecological
cancer. Opsoclonus is present in 75% of the patients. Patients without
opsoclonus may have other oculomotor abnormalities, including nystagmus,
abnormal visual tracking, blepharospasm, and abnormal vestibulo ocular
reflexes. Ataxia predominates in the trunk and may cause severe gait
difficulty and frequent falls. Limb ataxia is usually mild and most
patients retain the ability to write and feed themselves. Other symptoms
suggesting a more diffuse involvement of the brainstem include nausea,
dizziness, dysarthria, dysphagia, diplopia, rigidity, and parinsonism.
MRI studies are almost always normal.
The third type of brainstem encephalitis occurs with testicular cancer.
Patients developed brainstem encephalitis usually combined with limbic
encephalitis or diencephalic symptoms. A frequent finding is vertical
gaze paresis that may evolved to severe or total paralysis. Non-eye
movement abnormalities included, mild to moderate dysarthria, dysphagia,
facial weakness, and atypical parkinsonism with severe akynesia, facial
masking, rigidity, and tremor. MRI brain scans usually show hyperintense
T2-weighted images in the upper brainstem, hypothalamus, thalamus and
hippocampus (figure). The lesions rarely constrast enhance.
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Figure: MRI FLAIR sequences of a patient
with severe hypokinetic syndrome, non-aretic eye closure and reduction
verbal output, and anti-Ma2 antibodies showing abnormalities in
the mesial temporal lobes and dorsal mesencephalon |
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Associated antibodies
Most of the patients with brainstem encephalitis and SCLC present anti-Hu
antibodies. Other antibodies less frequently associated are anti-CV2(CRMP5)
and anti-amphiphysin. Anti-Ri antibodies
are usually present in patients with brainstem encephalitis and breast
cancer. Lastly anti-Ma2(Ta) antibodies
identify those patients with brainstem encephalitis and testicular cancer.
Treatment
As in other paraneoplastic neurological syndromes associated with neuronal
damage, brainstem encephalitis rarely improves with treatment. The best
chance to at least stabilize the syndrome is to induce a complete response
of the tumor. Immunotherapy rarely is effective but a trial with intravenous
immunoglobulins, steroids or plasmapheresis is indicated because there
are a few patient who improve. Patients with anti-Ma2 antibodies and
testicular cancer improve more frequently than those associated with
other onconeural antibodies.
Selected references
1. Ball JA, Warner T, Reid P, et al. Central alveolar hypoventilation
associated with paraneoplastic brai-stem encephalitis and anti-Hu antibodies,
J Neurol 1994;241:561-6.
2. Graus F, Keime-Guibert F, Reñé R, et al. Anti-Hu-associated
paraneoplastic encephalomyelitis: analysis of 200 patients. Brain 2001;124:1138-48.
3. Rosenfeld MR, Eichen JG, Wade DF, et al. Molecular and clinical diversity
in paraneoplastic immunity to Ma proteins. Ann Neurol 2001;50:339-48.
4. Sutton IJ, Barnett MH, Watson JDG, et al. Paraneoplastic brainstem
encephalitis and anti-Ri antibodies. J Neurol 2002;249:1597-8.
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