Myopathy, Neuropathy, CNS InfectionsRachel Garvin, MDAssistant Professor, Neurocritical CareDepartment of Neurosurgery

ObjectivesDescribe critical care myopathy

and neuropathy, causes, diagnosis and management

Describe CNS infections, diagnosis and management

Critical Illness Polyneuropathy (CIP) and Myopathy (CIM)Seen in conjunction with severe

sepsis and prolonged use of neuromuscular blockade +/- steroids

Seen in up to 40% of ICU patients

CIM/CIPFirst sign is often inability to

wean from ventilatorNot usually noted until patient at

least 2 weeks on ventilatorSevere diffuse weakness and

muscle wasting

CIPDiagnosis by EMGAxonal degeneration of motor

and sensory fibersCK is normalMuscle biopsy shows denervation

atrohpy

CIMEMG shows myopathic muscle

unitsElevated serum CKBiopsy shows myopathy with loss

of myosin

Recovery/ManagementNo specific treatment –

supportive careRange of levels of recovery

CNS INFECTIONS

CNS InfectionsMeningitis/VentriculitisEncephalitisBrain Abscess

MeningitisBacterial (septic) vs Other infectious or

inflammatory (aseptic)Most often caused by bacteremia that

seeds meninges by crossing BBB and multiplying in CSF

Ventriculitis more common in those with ventricular drains/shunts

Cerebral edema can occur d/t inflammatory effects of infection leading to vasogenic and cytotoxic edema

MeningitisClassic signs of fever, HA and

meningismus may not always be present (esp. elderly)

Also seen with photophobia, N/V, altered consciousness

Pathogens dependent on:◦Adult in community: strep pneumo,

neisseria, listeria◦Hospitalized patient: gram negatives

Meningitis Dx: LPElevated opening pressure

(>20cmH2O)Increased protein (>100mg/dl)Decreased glucose (<40% serum

level)Elevated nucleated cell count

(usually >100)

ComplicationsSIADH (50% of cases)SeizuresElevated ICP risk of herniation

TreatmentAbx appropriate to pathogenEnsure appropriate CNS dosingDuration from 14-21 days

depending on pathogen

EncephalitisInfection of brain parenchymaMultiple modes of infectionMost are hematogenous spread

except for HSV and rabies which spread via neurons

Most are viral

Encephalitis: PresentationVaries as certain infections have

certain locations they affect:HSV: inf/medial temporal lobes

and orbito-frontal cortexArboviruses (West Nile, equine):

cortical gray matter, brainstem and thalamic nuclei

Japanese B virus: brainstem nuclei and basal ganglia

Encephalitis: DiagnosisHistory and physicalNeuroimaging: CT and MRILP: many present as

meningoencephalitisHSV PCR may be falsely negative

in first 48 hours and then again 10 days after infection

Other viruses: IgM in CSF, viral culture from blood, tissue or CSF

Encephalitis: Treatment and OutcomesOnly treatment for HSV with

Acyclovir for 14 daysOther viruses are supportive care

only

Brain AbscessEncapsulated collection of pus

within brain parenchymaRisk factors include: head and

neck infections, penetrating head injury, immunocompromised state

Presentation often non-specific but can have symptoms related to location of abscess

Brain Abscess: PathophysiologyBegins as a cerebritis, day 1-3

with surrounding inflammation and edema

1 week into infection, central necrosis develops

By 14 days, fibrous capsule apparent which becomes more established

Brain Abscess: DiagnosisHistory and PhysicalCT + contrastMRINeedle-guided aspiration

Braun Abscess: ComplicationsSeizures are most common

morbidity (up to 70%)Abscess rupture leading to

meningitis/ventriculitisFormation of subdural empyema,

epidural abscess, septic thrombophlebitis

Brain Abscess: TreatmentIV abx based on pathogen or

presumed source (otitis, odontogenic)

Surgical drainage

CNS Fungal InfectionsSeen mostly in

immunocompromised patientsCan present in any form

(meningitis abscess)Often difficult to grow in cultureTreatment with ampho B