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Neuro Labs
Neurology
| Question | Answer |
|---|---|
| LP: indications: Dx | Obtain CSF for lab analysis; Determine spinal fluid pressure; administer radiopaque dyes into CNS for imaging |
| LP: indications: Tx | Administer drugs (Abx, CTx, anesthesia) into CNS; remove excess CSF |
| Diagnostic LP: | CNS infxn (meningitis, encephalitis); HA (SAH); Pseudotumor cerebri (idiopathic ICH); MS; Support dx of NPH & predict response to surgical shunting |
| LP: CI (1) | Suspected brain abscess (CSF study usu not helpful); Elevated ICP: esp if papilledema is present; Risk of brain damage / death from brain herniation |
| LP: CI (2) | Suspected mass lesion; Ventricular obstruction; Local infx at puncture site; Suspect epidural abscess; Anticoags/ coagulopathies/ low plt; Position-related cardioresp compromise; Acute spinal trauma or prior lumbar surgery |
| LP procedure | Informed consent; may sedate; pt on side, knees bent, chin to chest; antiseptic/ anesthetic |
| LP: insert needle into: | L3-L4 space |
| LP in kids: | spinal cord extends more caudally, do low LP |
| LP in extreme elderly: | may need to do cisternal procedure |
| LP Comorbidity | Local skin infection or disease, spinal deformity: cisternal procedure done if lumbar site not accessible |
| LP: Intrathecal variability | Higher conc pro & cells in lumbar sac than in ventricular or cisternal fluid (due to stagnation) |
| CSF collection: amount: | 1-2 mL CSF per tube |
| LP: Most common AE: | PDPH |
| PDPH: prevention: | small bore atraumatic spinal needle, needle bevel parallel to longitudinal fibers of dura, & reinsertion of stylet prior to needle removal |
| PDPH: Tx | time, bed rest, analgesics or epidural blood patch |
| Routine CSF analysis includes: | Opening pressure; Appearance/color; Consistency; Tendency to clot; Diff cell count; Protein; Glucose |
| Additional CSF analysis | Sediment stains (Gram, acid-fast); Culture (Bac, mycobac, yeasts/fungi); Serology (Syphilis, Ig (inc oligoclonal IgG in MS); Chem testing (Pro composition, bili, lactic a., urea, glutamine |
| CSF vs plasma: comp | Most constituents present in equal/lower levels than in plasma (BBB usu restricts lg molecules: pro, cells) |
| CSF cloudy: | Inc WBC or protein |
| CSF: Xanthochromia (yellow tinge): | hyperbilirubinemia, hypercarotenemia, melanoma |
| CSF: Red tinge | Blood from bleeding into SA space or traumatic tap |
| CSF: Cells | Normal 0-5 small lymphs/ml; PMNs, lg monos & RBCs are never normal |
| CSF: RBCs & WBCs: | only present via ruptured blood vessels or by meningeal response to inflammation or irritation |
| CSF Cell Count uses: | Detect CNS infection or malig; Monitor response to tx |
| WBC in CSF | Inc WBCs = inflam (>100, prob infxn); PMNs: bac infxn; Lymphs = viral or other (TB, fungal, ca); Eosinophils: shunt, parasitic infection & allergic rxn |
| CSF pressure | Normal 60-200 mm H2O (mean = 120); manometer (read after fluid stops rising); Position may increase P slightly (sitting, holding breath, mx tension); P usu drops 5-10 mm for each ml CSF removed |
| CSF pressure: Marked elevation: | consider purulent meningitis or intracranial tumors |
| CSF pressure: Moderate elevation: | consider mild inflammation, encephalitis, neurosyphilis |
| CSF pressure: Elevated pressure with normal CSF: | confirms pseudotumor cerebri (benign ICH): one instance where LP is done despite presence of papilledema |
| CSF protein: increased in: | inc permeability of blood-CSF barrier (tumor, trauma, inflam), or increased intrathecal synthesis of Igs |
| CSF protein: decreased in: | CSF protein leak, hyperthyroidism, water intoxication |
| CSF glucose | Cf to plasma/serum glu values; CSF glu 60-70% of plasma glu (50-80 mg/dl); Used to evaluate meningitis; Low levels: assoc w/ bacterial or TB infection |
| CSF lactate: | usu parallels blood levels; if markedly different from blood level = biochem abnormality in CSF |
| Increased CSF lactate associated with: | CVA, IC bleed, bacterial meningitis; Not altered in viral meningitis; lactate may differentiate btw viral & bacterial |
| Organism conc required for detection on CSF smear: | 10,000/ /ml (Gram & AFB stains may be neg despite org presence in CSF; cx on several media; consider empiric tx) |
| CSF antigen serology: | More rapid, but less specific, than cx; cryptococcal Ag test very specific/accurate |
| LP w/ decreased glucose, increased protein | Bacterial meningitis |
| LP w/ decreased protein, very few neutrophils | syphilitic meningitis |
| Emergent eval of stroke | CBC/plt; PT/ PTT; Lytes, glu, renal; ECG/ markers of cardiac ischemia; Brain CT or MRI |
| Seizure: labs | Glucose; lytes; AED levels; LP if poss meningitis; EtOH/tox if susp; ABG if susp hypoxia; poss CXR, CT, MRI |
| MS: CSF findings | oligoclonal bands, increased IgG index, myelin prodn/fragments |
| When do LP? | suspect meningitis; not if suspect abscess |
| Glucose depressed: usually: | bac mening, or TB or fungal |
| Increased WBC in CSF indicates: | inflammation (not necessarily infection) |
| Tuberculous meningitis dx studies | active TB elsewhere in body; CSF inc WBC (100-150), mostly lymphs; abnormal CXR; acid-fast normal |
| Brain tumor: VEGF | higher the VEGF, worse the prognosis; anti-VEGF Ab’s effective in xenografts |
| CNS neoplasm CSF | xanthochromic; inc pro, normal cell count & glucose |
| Wilson: labs | Serum ceruloplasmin (Cu carrying pro) very low; urine Cu high |
| Use LP only after: | normal CT obtained & platelet count is normal |
| LP should be performed if: | Neuroimaging is normal or suggests dz that must be dx by measuring cerebrospinal fluid (CSF) pressure, cell count, and chem |
| Coma: labs | GLUCOSE, lytes, renal, Ca, PO4, ABG, CBC, tox screen; CXR, imaging (after stabilization) |
| Diagnostic LP: indications | CNS infxn (meningitis, encephalitis); HA (SAH); Pseudotumor cerebri (idiopathic ICH); MS; Support dx of NPH & predict response to surgical shunting |
| LP: CI | Suspected brain / epidural abscess; elevated ICP, esp if papilledema; suspect mass lesion; Ventricular obstn; |
| LP: insert needle into: | L3-L4 space (elderly: may need to do cisternal procedure) |
| LP in kids: | spinal cord extends more caudally, do low LP |
| CSF collection: amount: | 1-2 mL CSF per tube |
| Routine CSF analysis includes: | Opening pressure; Appearance/color; Consistency; Tendency to clot; Diff cell count; Protein; Glucose |
| CSF cloudy = | Inc WBC or protein |
| CSF: Xanthochromia (yellow tinge) = | hyperbilirubinemia, hypercarotenemia, melanoma |
| CSF: Red tinge = | Blood from bleeding into SA space or traumatic tap |
| CSF: Cells | Normal 0-5 small lymphs/ml; PMNs, lg monos & RBCs are never normal |
| CSF: RBCs & WBCs: | only present via ruptured blood vessels or by meningeal response to inflammation or irritation |
| WBC in CSF | Inc WBCs = inflam (>100, prob infxn); PMNs: bac infxn; Lymphs = viral or other (TB, fungal, ca); Eosinophils: shunt, parasitic infection & allergic rxn |
| CSF pressure | Normal 60-200 mm H2O (mean = 120); usu drops 5-10 mm for each ml CSF removed |
| CSF pressure: Marked elevation: | poss purulent meningitis or intracranial tumors |
| CSF pressure: Moderate elevation: | mild inflammation, encephalitis, neurosyphilis |
| CSF pressure: Elevated pressure with normal CSF: | confirms pseudotumor cerebri (benign ICH): one instance where LP is done despite presence of papilledema |
| CSF protein: increased in: | inc permeability of blood-CSF barrier (tumor, trauma, inflam), or increased intrathecal synthesis of Igs |
| CSF protein: decreased in: | CSF protein leak, hyperthyroidism, water intoxication |
| CSF glucose | Normal CSF glu 60-70% of plasma glu; Low levels assoc w/ bacterial or TB infection |
| CSF lactate: | usually parallels blood levels; if markedly different from blood level = biochem abnormality in CSF |
| Increased CSF lactate associated with: | CVA, IC bleed, bacterial meningitis; Not altered in viral meningitis; lactate may differentiate btw viral & bacterial |
| Organism concentration required for detection on CSF smear: | 10,000/ /ml (Gram & AFB stains may be neg despite org presence in CSF; cx on several media; consider empiric tx) |
| CSF antigen serology: | More rapid, but less specific, than cx; cryptococcal Ag test very specific/accurate |
| Primary lateral sclerosis: dx studies | EMG, MRI (br & spcord), LP, evoked potls; B12, Lyme, RPR, long chain fatty acids |
| Myasthenia gravis Dx studies | Tensilon test; Ach receptor & MuSK Abs; Repetitive nerve stim; Single fiber EMG; CT Chest to exclude thymoma |
| MD: labs/studies | ultrastructural protein abnormalities; mx bx: mx fiber necrosis |
| Duchenne/Becker: Dx studies | Mx bx; genetic testing (need complete sequencing); CK sometimes >10,000; FH |
| Wilson: dx | high ceruloplasmin & copper; low copper on liver bx; Kayser Fleischer rings |
| Duchenne/Becker Dx | genetic testing, elevated CK, EMG |
| Pathological hallmark of Parkinson: | Lewy body (alpha-synuclein is main component) |
| MELAS dx studies | Mitochondrial inheritance, labs: high pyruvate / lactate; stroke lesions (don’t conform to normal vasc distn) |
| oligoclonal bands in CSF = | MS |
Created by:
Abarnard
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