Encephalitis in a Healthy Individual Flashcards
Most common causes of viral encephalitis
- HSV (or related herpesvirus)
- Enterovirus
- West Nile virus
- St. Louis virus
When viral encephalitis is on the differential, it is best to. . .
. . . treat empirically with acyclovir until the results of HSV PCR come back negative
This is the only treatable cause of viral encephalitis, and acyclovir is unlikely to make the situation worse.
Limbic encephalitis
-
Autoimmune encephalitis syndrome that may be idiopathic or triggered by malignancy
- Refers to a set of many autoimmune syndromes caused by type III hypersensitivity to an array of antigens (including anti-NDMA receptor)
- Often in cases of autoimmune encephalitis, no specific causative antigen is identified, but patients do respond to immunosuppression and plasma exchange
- Affects primarily the temproal lobes, limbic system, and orbitofrontal cortex
- Note that the distribution is very similar to HSV encephalitis, which is always on the differential
Empiric therapy for limbic encephalitis of suspected autoimmune etiology
- Only begin therapy ONCE VIRAL ETIOLOGIES HAVE BEEN RULED OUT
-
First-line:
- Plasma exchange
- IVIG
- High dose IV corticosteroids
-
Second-line:
- Rituximab
- Cyclophosphamide
-
Definitive:
- If due to a paraneoplastic syndrome from a teratoma, resection of the teratoma is often curative
If HSV is the etiology of viral encephalitis in a patient, what will you often see on lumbar puncture?
Xanthochromia
Anti-NDMA receptor encephalitis
- Common autoimmune or paraneoplastic etiology of limbic encephalitis
- Classical presentation:
- Occurs most frequently in young women
- Begins with flu-like prodrome
- Followed by acute-onset psychosis, memory deficit, and dyskinesias
- Subsequent development of depressed consciousness, seizures, dysautonomia, and coma
- Associated with ovarian teratomas
- Diagnosis:
- Antibody detection in CSF or serum
- MRI normal in 70% of cases
- CT chest/abd/pelvis to search for a teratoma
- EEG typically shows generalized slowing, which can help distinguish from schizophreni
Nature of the type III hypersensitivity effect in anti-NDMA receptor encephalitis
Blocking of the NDMA-glutamate receptors by these antibodies leads to disinhibition of the frontal cortex – from which most of the intitial neurologic symptoms of the presentation are derived
In this regard, it is similar to high levels of PCP or ketamine, which are both NDMA receptor antagonists
Classic malignant association of NDMA receptor encephalitis
Teratoma (often ovarian)
Chronic epilepsy after viral enephalitis
Most common following HSV encephalitis
50% of cases multifocal or generalized, but of those patients with an aura ~2/3 of them had limbic-mesial temporal auras
This is probably because HSV has a predeliction for infecting the mesial temporal lobes.
Anti-Hu
- Limbic encephalitis antibody
- Syndrome: Encephalomyelitis, cerebellar degneration, sensory ganglionopathy
- Associated cancers: SCLC
Anti-Yo
- Paraneoplastic antibody
- Syndrome: Cerebellar degeneration
- Associated cancers: Gynecologic, breast
Anti-Ri
- Paraneoplastic antibody
- Syndrome: Cerebellar degeneration, brainstem encephalitis, opsoclonus-myoclonus
- Associated cancers: Gynecologic, breast, SCLC
Anti-Ma
- Paraneoplastic antibody
- Syndrome: Limbic, hypothalamic, and brainstem encephalomyelitis
- Associated cancers: Testicular germ cell tumors, lung cancer
Anti-CV2/CRMP5
- Paraneoplastic antibody
- Syndrome: Encephalomyelitis, cerebellar degeneration, chorea, peripheral neuropathy
- Associated cancers: SCLC, thymoma
Anti-Caspr2
- Paraneoplastic antibody
- Syndrome: Morvan syndrome, limbic encephalitis, peripheral neuropathy, cerebellar ataxia, neuromyotonia
- Associated cancers: Thymoma
