Page 943 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

674 PART 5: Infectious Disorders

seizures, decreased cognition, delirium, motor and sensory deficits. A less common neurologic complication of measles infection is sub-
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Neurologic sequelae seen with IAE are impaired cognition, mutism, acute sclerosing panencephalitis (SSPE). It is a chronic, degenerative
behavioral changes, ataxia, paralysis, dystonia, and hand tremor. Along CNS disease from a defective viral production of membrane or envelope
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with the clinical syndrome, diagnosis is based on laboratory, neuroimag- proteins and occurs on an average of 6 years after the initial infection.
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ing, and EEG confirmation. Positive viral culture, viral antigen detec- The prevalence is estimated at 1 per 100,000 cases. The onset is insidi-
tion, and viral RNA PCR are used. Neuroimaging may show diffuse ous with subtle personality changes, prominent psychiatric manifesta-
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cerebral cortical involvement with edema in severe cases. The acute tions, myoclonic seizures, motor disturbances, and ultimate akinetic
necrotizing form shows multifocal, symmetric, necrotizing lesions in mutism. Often, coma and death follows. This condition occurs particu-
the brain. EEG abnormalities include focal diffuse slowing or sharp larly in those who had measles before the age of 2 years and it occurs
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waves in the frontal or temporal area and seizures. Other common despite a vigorous host immune response to the virus. The diagnosis is
encephalitides should be excluded. Antiviral therapy with amantadine clinical, supported by periodic complexes on electroencephalography,
and oseltamivir is used. Febrile seizures, Reye syndrome, postinfluenza brain imaging suggestive of demyelination, and increased levels of
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encephalitic Parkinson, encephalitis lethargica are some of the other globulin and measles antibody in CSF or detection of viral RNA. 102,103
neurologic manifestations of influenza. 93 Management is supportive with seizure control and prevention of sec-
ondary complications. Trials with ribavirin, interferon, and isoprinosine
PARAMYXOVIRIDAE have shown some benefit. 104,105 However, only 5% of SSPE patients
■ MUMPS VIRUS 5 years. Subacute measles encephalitis (SME) is a third form of
undergo spontaneous remission and 95% of them eventually die within
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Mumps virus is an enveloped RNA virus that belongs to the family measles encephalitis that occurs mainly in immunosuppressed children
in whom it acts like an opportunistic infection. Measles virus RNA can
Paramyxoviridae. The hallmark of infection is parotid gland swelling. be detected in the brain of SME patients and it follows a rapidly progres-
Aseptic meningitis, encephalitis, orchitis, oophoritis, pancreatitis, and sive course. 106
deafness are some of the complications. Mumps is a highly contagious
infection restricted to human beings and is transmitted by direct con- ■ NIPAH VIRUS
tact, droplet spread, or contaminated fomites. The virus enters the
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cerebrospinal fluid (CSF) via the choroid plexus or infected mononu- Nipah virus is a highly pathogenic paramyxovirus that first emerged in
clear cells during plasma viremia. Though CSF pleocytosis is common, Malaysia and Singapore in 1999. It was responsible for the outbreak of
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clinical meningitis occurs in only up to 10% of patients. Meningitis is a febrile encephalitis mostly in adult males in close contact with pigs.
common benign condition with no mortality or long-term sequelae. In Since its initial description it has subsequently caused fatal human
up to 50% of cases, mumps meningitis occurs in the absence of salivary encephalitis in India and Bangladesh. Nipah virus is closely related to
gland involvement. Encephalitis on the other hand is a rare but serious another zoonotic paramyxovirus, Hendra virus, which infects horses
entity seen in 0.1% of patients. The presence of seizures, pronounced and rarely humans. After an incubation period of 10 days, patients pres-
changes in the level of consciousness, and focal neurological symptoms ent with nonspecific symptoms such as fever, headache, myalgia, sore
are indicative of mumps encephalitis. There is bimodal distribution of throat, and altered mental state along with distinctive clinical signs like
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illness: an early onset illness that coincides with parotitis and represents segmental myoclonus, areflexia, hypertension, and tachycardia. Nipah
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damage to neurons directly due to viral invasion, and a more common virus specific ELISA is useful in diagnosing infection. Treatment with
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late onset illness that develops 7 to 10 days after the onset of parotitis, ribavirin was shown to reduce mortality. The mortality rate reported
which is a postinfectious demyelinating process (ADEM). The virus from the outbreak in Malaysia was 41%, while it was close to 70% in
may be isolated from CSF on tissue culture. Immunofluorescence and Bangladesh and India. 111
PCR also help in virus detection. Serology-like virus-specific IgM and
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IgG in CSF is useful in confirming the diagnosis. There is no specific ADENOVIRIDAE
antiviral treatment for mumps; management is supportive and symp-
tom based. Other neurologic syndromes rarely associated with mumps Adenovirus has been associated with meningitis and encephalitis in
include deafness, cerebellar ataxia, facial palsy, transverse myelitis, children and immunocompromised patients, and can present as the
ascending polyradiculitis, and a poliomyelitis-like syndrome. The best primary manifestation or as a complication of respiratory tract infec-
prevention is by a live attenuated mumps vaccine, but recent outbreak tion. CSF cell count, glucose and protein concentration are variable and
occurred in USA even in vaccinated people. The reason for this is not helpful in establishing the etiologic diagnosis. A definite diagnosis
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unclear and needs further research. can be made by viral culture or PCR of CSF or brain tissue. Treatment
is supportive.
■ MEASLES VIRUS
Measles is highly contagious RNA virus of the Paramyxoviridae family. BACTERIAL ENCEPHALITIS
tacts, especially unvaccinated children and adults. This virus is spread ■ BARTONELLA SPECIES
The secondary attack rate is at least 90% in susceptible household con-
through respiratory droplets; there have been recent increases in the Infections due to Bartonella species can involve the CNS and cause
incidence of measles. Acute encephalitis is the most common neu- encephalitis. Exposure to cats through bites and scratches can result
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rologic complication of measles, seen more commonly in adults than in infection with Bartonella henselae, the etiologic agent of cat scratch
in children with an incidence of 1 in 1000 to 2000 patients. It occurs disease (CSD). Cat fleas have also been implicated in the transmission
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during the convalescent phase, typically a week after the onset of rash, of the bacteria. CSD is a disease seen most often in young adults and
and presents as abrupt onset of fever, along with headaches, seizures, and children and in 90% of cases it manifests as an ulcer at the site of inocu-
altered consciousness. These manifestations may be mild or severe, but lation of B henselae, which appears within 7 to 10 days of exposure and
can lead to permanent neurologic sequelae in a substantial number of subsequently develops tender enlarged regional lymph nodes, which
patients. It is not clear whether this is due to direct invasion or a postin- may suppurate. CSD is often a self-limited illness, but in some the organ-
fectious process from a hypersensitivity reaction to the virus. The ism may disseminate to involve many organs including the CNS. CNS
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abrupt onset of the encephalomyelitis in the setting of the typical exan- involvement can present as encephalitis, which is the most common
them is a characteristic feature that helps differentiate this from other form of presentation. Onset of symptoms of encephalitis such as confu-
forms of viral encephalitis that have a more gradual onset. Treatment is sion and disorientation begins about 5 to 6 weeks after the initial ulcer-
supportive with fluids and antipyretics. 100 node syndrome and may progress to coma. Seizures, focal neurologic

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