Baylor University Medical Center Proceedings April 2014, Volume 27, Number 2 | Page 36

granular neurons in the dorsal vermis of the cerebellum. Because
the antibodies can vary widely and sometimes are not found at
all, the exact mechanism is not entirely clear (10).
OMS has horizontal and vertical saccades. Horizontal saccades are generated by burst neurons in the paramedian pons,
and vertical saccades are caused by burst neurons in the rostral
midbrain. The activity of these burst neurons is controlled by
omnipause neurons in the pontine raphe. It is suggested that
OMS is caused by the failure of omnipause neurons to control burst neurons (8). The omnipause neurons are affected in
brainstem encephalitis and also when there is impaired control
of the brainstem saccade generating network by the cerebellum.
Patients with OMS should undergo a complete evaluation for
cancer and infection. Abnormal immunoglobulin analysis and
other laboratory findings may be nonspecific, since there are
no diagnostic biomarkers for paraneoplastic OMS. Blood or
CSF analysis may assist in identifying an infectious etiology.
While they neither diagnose nor exclude a paraneoplastic or
autoimmune etiology, CSF studies often document paraneoplastic antibodies, mild increases in proteins, and a lymphocytic
pleocytosis consistent with inflammatory changes (10).
The exact role of IVIG and high-dose steroids in the treatment of WNV has not been studied. However, improvements
have been reported in several instances for severe cases of human enteroviral encephalitis. Sequelae such as hearing loss of
infectious aseptic meningitides in general have been shown to
be reduced in children with steroid treatment. IVIG products
prepared in areas where WNV is endemic such as Texas have
been shown to have high titer levels to WNV. The timing and
route of administration of IVIG also appears to be important
(9). In the case presented, IVIG was administered 5 days after
onset of OMS (12 days after the rash and fever), along with
high-dose intravenous steroids and antivirals with initial rapid
improvement followed by very slow improvement and plateauing. It is impossible to determine the exact role of acute use of
IVIG and steroids in the recovery of our patient.

110

In general, neuroinvasive WNV infections can have
numerous presentations. Patients who present with OMS
with signs of an infective process should be checked for WNV
infection especially if they live in endemic areas. Patients
surviving WNV neuroinvasive disease often suffer long-term
neurological sequelae (4), and it is unclear if therapies offered
for other aseptic meningitides would apply. As is the case with
meningitis in general, it may be reasonable to consider steroids
or other immunomodulatory therapies to limit neuronal injury
in WNV neuroinvasive disease as well.
1.

Asnis DS, Conetta R, Teixeira AA, Waldman G, Sampson BA. The West
Nile virus outbreak of 1999 in New York: the Flushing Hospital experience.
Clin Infect Dis 2000;30(3):413–418.
2. Beckhan J, Tyler K. Encephalitis. In Mandell GL, Bennett JE, Dolin R,
eds. Principles and Practice of Infectious Diseases (7th ed. ). Philadelphia:
Elsevier Churchill Livingstone, 2009: 1243–1264.
3. Steinman A, Banet-Noach C, Tal S, Levi O, Simanov L, Perk S, Malkinson
M, Shpigel N. West Nile virus infection in crocodiles. Emerg Infect Dis
2003;9(7):887–889.
4. Murray KO, Mertens E, Despres P. West Nile virus and i ts emergence in
the United States of America. Vet Res 2010;41(6):67.
5. Bleck T. Arthropod-borne viruses affecting the central nervous system.
In Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine (24th ed.).
Philadelphia: Saunders Elsevier, 2011: chapter 391.
6. Montgomery SP Chow CC, Smith SW, Marfin AA, O’Leary DR, Campbell
,
GL. Rhabdomyolysis in patients with West Nile encephalitis and meningitis.
Vector Borne Zoonotic Dis 2005;5(3):252–257.
7. Smith RD, Konoplev S, DeCourten-Myers G, Brown T. West Nile
virus encephalitis with myositis and orchitis. Hum Pathol 2004;35(2):
254–258.
8. Anninger WV, Lomeo MD, Dingle J, Epstein AD, Lubow M. West
Nile virus-associated optic neuritis and chorioretinitis. Am J Ophthalmol
2003;136(6):1183–1185.
9. Shaikh S, Trese MT. West Nile virus chorioretinitis. Br J Ophthalmol
2004;88(12):1599–1600.
10. Alshekhlee A, Sultan B, Chandar K. Opsoclonus persisting during sleep
in West Nile encephalitis. Arch Neurol 2006;63(9):1324–1326.
11. Ramat S, Leigh RJ, Zee DS, Optican LM. Ocular oscillations generated
by coupling of brainstem excitatory and inhibitory saccadic burst neurons.
Exp Brain Res 2005;160(1):89–106.

Baylor University Medical Center Proceedings

Volume 27, Number 2