Outline of
Neurosurgery
E. R. Flotte, 2008
Cerebral abscess
·
Most common organisms: anerobic/
microaerophilic Strep.
o
Immunocompromised: Nocardia (disseminated with skin lesions), Toxo.
o
Neonates: GNR, Proteus, Citrobacter.
·
Predisposing factors: Sinus/dental infection,
pulmonary abscess/empyema, cyanotic cardiac disease (Tetralogy, kids), pulmonary AVF (Osler-Weber-Rendu,
hereditary hemorrhagic telangectasia), endocarditis (rare), AIDS
·
Symptoms: 50% have low-grade fever.
·
Lab: CXR, ESR/CRP, CBC (WBC >10K), BCx (10% positive), HIV, Toxo
testing. LP contraindicated.
·
Imaging
o
Cerebritis vs encapsulated abscess: On delayed CT capsule enhancement
decays, cerebritis doesn’t. Cerebritis
usually thicker
o
MR-Spect: ↑ lactate, acetate, pyruvate. May use to
follow response to treatment. Also WBC-tagged scans.
·
Treatment
o
Medical: antibiotics ± steroids
o
Indications: Cerebritis,
<3cm abscess, multiple, deep, eloquent cortex, <2 weeks of symptoms.
o
Steroids controversial: may delay encapsulation, but
most evidence argues against routine use. Usually used
only if significant edema present.
o
Antibiotics: 6 weeks IV then 6 weeks oral. Vanc/Rocephin/Flagyl
(empiric). Nocardia = Bactrim.
Toxo = Pyrimethamine +
Sulfadiazine. Anaerobic GNR (Bacteroidies) = Flagyl. Strep = PCN. Staph epi = Vanc ± Rifampin. Staphj aureus = nafcillin. Fungal
= Ampho B.
o
Surgical:
o
Indications: Encapsulated, periventricular
(>80% mortality w/rupture), >3cm, mass effect, diagnosis unclear,
difficult follow-up, medical failure (increased after 2wks or no change after
4wks)
o
Aspiration:
o
Excision: Aspirate first then corticectomy
& capsule excision (in noneloquent areas).
Preferred for penetrating trauma, fungal, multiloculated,
failure of repeated aspirations, posterior fossa, gas-containing.
o
Follow-up: Continue antibiotics for 6-8wks
(12wks if empiric) then may d/c even if CT abnormalities persist (may take
3-6mos to resolve). CT q2-4 wks until CT resolution, then q2-4mos for 1yr.
Subdural empyema
·
Usually secondary to sinusitis/otitis
in young people. Strep & Staph aureus are most common organisms. Causes
cortical vein thrombosis.
·
Treatment: emergent craniotomy (craniectomy?).
Do not remove membrane adherent to cortex.
Skull
Osteomyelitis
·
Give 3 months of antibiotics, replace bone in 6
months
AIDS
·
Focal lesions: most common are
o
Toxoplasmosis: most common (75%). Large hypodense area with edema and ring-enhancement. Common in
basal ganglia. Treatment: pyrimethamine and
sulfadiazine.
o
Progressive Multifocal Leukoencephalopathy (PML): due to JC papovavirus.
Demyelimation occurs. Hypodense,
hyperintense on T2, no edema or enhancement.
Invariably fatal – no effective treatment.
o
Primary CNS Lymphoma. Enhance strongly (may rim
enhance or are “target lesions” in AIDS lymphoma). Associated with Epstein-Barr
virus. Treatment: WBRT.
o
Also: cyrptococcal abscess
(more commonly meningitis)
·
Management:
o
PML can be differentiated by lack of enhancement.
o Obtain CSF
for cytology (lymphoma), PCR for EBV and serum toxo
titers.
o AAN guidelines for the
management of patients with AIDS state only
an isolated ring-enhancing lesion in the setting of negative
toxoplasmosis serology requires early biopsy. Otherwise, a trial of pyrimethamine and sulfadiazine is considered appropriate
for treatment of presumptive toxoplasmosis.
o
Single lesions are more likely lymphoma than toxo.
o
Biopsy role in non-enhancing lesions are unclear –
most are PML or non-specific.
·
Cryptococcus causes meningitis
·
Infection of larvae of pork tapeworm Taenia solium. Most
common CNS parasitic infection.
·
Tapeworm (intestinal) infection results from eating undercooked
pork. Cystercercosis results from eating tapeworm
eggs (ie through fecal contamination of food or
autoinoculation).
·
Endemic in
·
Incubation: months to >10years.
·
Seizures common
·
May be meningeal,
parenchymal, ventricular. Usually ring-enhancing
lesions with minimal edema. May have subcutaneous nodules.
·
Diagnosis: MRI – cyst, scolex
may appear as mural nodule.
o
Serum (25% sensitive) and CSF (50% sensitive)
antibody titers can be checked. CSF may show eosinophilia.
·
Treatment: Albendazole x 1
wk (more effective than Praziquantel) and steroids
(up to 30mg/d decadron and 10mg qod
chronically).
o
Biopsy may not be required when imaging and clinical
are suggestive according to some sources (SANS).
o
Ventricular cysts: surgical resection vs antihelminthics and shunting
(higher rate of malfunction). Consider endoscopic resection+- 3rd
ventriculostomy
o
Contacts: Single dose of praziquantel
·
Rarer parasities: echinococcus (hydatid cyst) – dog
tapeworm (may grow to be large, be careful not to rupture cyst –
Fungal
meningitis/abscess: Cryptococcus, candidiasis, mucorycosis (diabetics), aspergillosis (transplants)
Gradenigos Syndrome: osteomyelitis of petrous apex. CN6 palsy & retroorbital
pain, from otitis
Whipple disease: Caused by bacteria Tropheryma whippelii.
Symptoms: gastrointestinal symptoms and migratory arthralgias.
Path: perivascular macrophages with
diastase-resistant PAS (+) granules. Involves CNS in 25%: dementia, multifocal grey-matter lesions, especially temporal cortex,
thalamus, etc.
Herpes
Encephalitis
·
See Neurology:
Herpes Encephalitis
·
Preferentially affects temporal lobes. Diagnosis: PCR
on CSF.
·
Biopsy rarely needed unless diagnosis is unclear.
Open anterior temporal cortical/subcortical biopsy
with viral isolation.
·
Treatment: acyclovir (begin immediately empirically).
·
MRSA wound infection: IV Vancomycin
and po Rifampin x 6 weeks
·
Staph aureus most common organism.
·
Surgical debridement options: laminectomy; anterior
decompression with or without anterior and/or posterior instrumentation (staged
or simultaneous)
o
Cage with autograft preferred over allograft strut by
some
o
It is generally felt that instrumentation can be placed
in the setting of infection (during primary debridement)
o
See Neurosurg
Focus 12/04
Osteomyelitis
·
Cultures usually obtained by CT-guided needle biopsy.
Send Gram, fungal, and AFB stains, cultures for aerobic, anaerobic, fungal and
TB
·
Osteomyelitis involves the disc space (discitis),
spinal mets do not (Cancer = C-shape around the disc)
·
Can use ESR, CRP to follow treatment.
·
Treatment: Generally manage with antibiotics and
bracing if neurologically and mechanically stable
·
Indications for reconstruction and stabilization
controversial but include: instability, neurologic deficit, or significant
canal compromise
·
Pott’s disease:
Tuberculosis vertebral osteomyelitis. Psoas abscess (often calcified) common,
spares disc space (pathognomonic). Treatment usually medical – 12 months +.
Discitis
·
Discitis may occur
without osteomyelitis
·
Discitis can be postoperative or occur spontaneously
in adults (with same risk factors as spinal epidural abscess) or juveniles
(average 2-3 years-old – due to persistence of nutrient feeding arteries). In
children presents as refusal to walk.
·
Generally treated with antibiotics and bracing if the
organism can be identified by urine or blood cultures or needle aspirate
Spinal
epidural abscess
·
Symptoms: Similar to osteo:
back pain, fever, tenderness (with neurologic deficit).
·
Risk factors: immunocompromise, IV drug use,
diabetes, alcoholism.
·
Most common organisms: Staph aureus.
·
Treatment:
o
Extensive length (panspinal) or complete deficits for
>3 days: immobilization (TLSO) and antibiotics (4wks IV then 4wks oral). (If
no deficits & minimal compromise
require close monitoring and is controversial)
o
Neurologic Deficits or canal compromise (most cases):
emergent evacuation.
Revised 4/14/08
Text Copyright 2008