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PE27.1-14 | Central Nervous System — Graded Quiz
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A 2-year-old child presents with 2 days of fever, vomiting, and progressive obtundation. CSF shows 4200 cells/mm³ (85% PMNs), glucose 18 mg/dL, protein 220 mg/dL (simultaneous blood glucose 90 mg/dL). Gram stain: Gram-positive diplococci. Which treatment regimen is MOST appropriate?
Gram-positive diplococci = S. pneumoniae. Current recommendation is ceftriaxone + vancomycin (to cover penicillin/cephalosporin-resistant pneumococcus) + dexamethasone (given before or with first antibiotic dose to reduce inflammation and sequelae). CSF glucose ratio = 18/90 = 0.2 (severely low, bacterial). Duration for pneumococcal meningitis is 10-14 days.
Pneumococcal meningitis treatment: IV ceftriaxone + vancomycin (empirical, until sensitivities) + IV dexamethasone 0.15 mg/kg 6-hourly × 4 days (give with or before first antibiotic). Duration: 10-14 days for pneumococcal, 7 days for meningococcal, 21 days for GBS.
Ampicillin + gentamicin is for neonatal meningitis (GBS, E. coli, Listeria). Cefotaxime alone misses resistant pneumococcus. Oral antibiotics cannot achieve adequate CSF penetration for bacterial meningitis.
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A 5-year-old child is diagnosed with TBM Stage II (Bhatt classification). Which of the following combination is MOST important to include in management to reduce mortality and disability?
TBM requires 12 months of ATT (2HRZE intensive + 10HR continuation) per NTEP guidelines. Dexamethasone (or prednisolone) is recommended for ALL stages of TBM (Stages I, II, and III) as it reduces inflammation, cerebral oedema, and mortality. Ethambutol has good CNS penetration during meningeal inflammation.
TBM = 2HRZE + 10HR (total 12 months, NTEP) + adjuvant dexamethasone/prednisolone for ALL stages. Three stages (I: alert, no deficit; II: meningism + cranial nerve palsy/hemiplegia; III: deep coma/decerebrate). Cobweb clot in CSF is a characteristic but non-specific finding.
6 months of ATT (standard pulmonary TB regimen) is insufficient for TBM — CNS penetration requires the extended 12-month regimen. Streptomycin is not substituted for ethambutol in TBM per current NTEP guidelines. Steroids benefit ALL stages, not just Stage III.
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A lumbar puncture yields CSF with: appearance — water-clear; cells — 280/mm³ (95% lymphocytes); glucose 60 mg/dL (simultaneous blood glucose 90 mg/dL); protein 65 mg/dL; no organisms on Gram stain. What is the MOST likely diagnosis?
Viral meningitis: clear CSF, lymphocytic pleocytosis, glucose normal or mildly reduced (CSF:blood ratio = 60/90 = 0.67, which is normal [>0.5]), mildly elevated protein (50-100 mg/dL), no organisms on Gram stain. The benign picture with normal glucose strongly favours viral (enteroviruses most common in children).
CSF interpretation pearl: the CSF:blood glucose ratio is the most discriminating single value. >0.5 = viral/normal; 0.3-0.5 = indeterminate (may be TBM or early bacterial); <0.4 = bacterial; <0.3 = TBM/fungal. Always interpret with the cell differential and protein.
Bacterial: neutrophilic, glucose severely low (<0.4 ratio), protein >100 mg/dL, turbid. TBM: lymphocytic but glucose very low (often <0.3 ratio), protein very high (100-500 mg/dL), cobweb clot, subacute onset. Fungal: lymphocytic, very low glucose, India ink positive (cryptococcus).
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A 6-week-old infant presents with rapidly enlarging head, bulging fontanelle, and vomiting. Ultrasound shows dilated all four ventricles with dilated aqueduct of Sylvius. This is MOST consistent with which type of hydrocephalus?
Dilatation of all four ventricles WITH a dilated aqueduct of Sylvius indicates obstruction AT or BELOW the aqueduct — the classic finding of aqueductal stenosis. This is non-communicating (obstructive) hydrocephalus. In communicating hydrocephalus (post-meningitis, choroid plexus papilloma), the aqueduct is patent and CSF flows freely to subarachnoid space.
Hydrocephalus classification: obstructive (non-communicating) — aqueductal stenosis, tumour, Chiari; communicating — post-meningitis, post-haemorrhagic, choroid plexus papilloma. Treatment: VP shunt (most common) or endoscopic third ventriculostomy (ETV) for obstructive type in children >1 year.
Communicating hydrocephalus (post-meningitis): all ventricles dilated, patent aqueduct, obstruction at arachnoid granulations — ventricles all dilate but the aqueduct is NOT the obstruction site. Dandy-Walker: absent/hypoplastic vermis + large posterior fossa cyst — fourth ventricle is cystically dilated, not all ventricles proportionally.
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A 2-year-old girl has left-sided hemiplegia with increased tone, exaggerated reflexes, and fisting of the left hand following perinatal asphyxia. Her development is otherwise normal. Which cerebral palsy type does she MOST likely have?
Spastic hemiplegia involves one side of the body (arm > leg), with UMN signs (spasticity, hyperreflexia, Babinski). It typically results from unilateral cortical/subcortical lesions — often from perinatal stroke, arterial occlusion, or periventricular haemorrhage affecting one hemisphere. Cognitive function is often relatively preserved.
Cerebral palsy GMFCS grades I-V (Grade I = walks without restrictions; Grade V = cannot maintain posture). Spastic hemiplegia is associated with unilateral cortical lesions; spastic diplegia with PVL (premature); dyskinetic with basal ganglia injury (kernicterus). Management: physiotherapy, orthotics, botulinum toxin, surgical (selective dorsal rhizotomy).
Spastic diplegia: bilateral lower limbs > upper limbs (prematurity/PVL). Dyskinetic CP: involuntary movements (choreoathetosis/dystonia), associated with kernicterus or severe asphyxia involving basal ganglia. Ataxic CP: cerebellar involvement, hypotonia, intention tremor, gait ataxia.
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A 2-year-old girl presents with intellectual disability, small head circumference (microcephaly), and self-hugging movements with hand-wringing. Development was normal up to 6 months then regressed. EEG shows generalised slow waves. Which syndrome is MOST likely?
Rett syndrome: X-linked dominant (MECP2 mutation), affects girls almost exclusively. Classic presentation: normal development to 6-18 months → regression → loss of purposeful hand use → characteristic hand-wringing or hand-wringing stereotypies, microcephaly, intellectual disability, autistic features, seizures. Angelman: happy disposition + seizures + absent speech. Down: trisomy 21 features. Fragile X: large ears, macroorchidism, affects boys mainly.
Intellectual disability (mental retardation, IQ <70) classified as mild (50-70), moderate (35-50), severe (20-35), profound (<20). Common causes in India: perinatal asphyxia, iodine deficiency (congenital hypothyroidism), chromosomal (Down, fragile X). Rett syndrome is a specific cause in girls with regression and hand stereotypies.
Down syndrome has recognisable dysmorphic features (flat nasal bridge, upslanting palpebral fissures, single palmar crease) and does not regress after normal development. Angelman is characterised by happy, sociable behaviour + jerky movements + seizures. Fragile X is the most common inherited intellectual disability in boys.
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A 4-year-old boy with a convulsive seizure arrives in the emergency room. He has been seizing continuously for 8 minutes. IV access is established. He has already received one dose of IV lorazepam 0.1 mg/kg 5 minutes ago with no response. What is the NEXT most appropriate step?
After failure of benzodiazepine therapy (one or two doses), the next step is second-line therapy: IV phenytoin 20 mg/kg at ≤1 mg/kg/min (max 50 mg/min in adults; monitor ECG for arrhythmia and hypotension). Alternatively, IV sodium valproate 20-40 mg/kg or IV levetiracetam 40-60 mg/kg can be used as second-line options.
Status epilepticus algorithm: 0-5 min: IV/IO lorazepam 0.1 mg/kg; 5-20 min: second-line (phenytoin 20 mg/kg IV, or valproate 20-40 mg/kg, or levetiracetam 40-60 mg/kg); 20-40 min: repeat second-line or add another second-line; >40 min: refractory SE → ICU, intubation, anaesthetic agents (thiopentone/midazolam infusion).
A second benzodiazepine dose can be given if the first dose was inadequate, but if one full dose has already been given and failed, the next step is a second-line antiepileptic. IM midazolam is an alternative when IV access is unavailable, not after IV access is established. Dexamethasone does not terminate seizures.
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A 5-year-old child presents with febrile seizures. Which feature would MOST classify this as a COMPLEX febrile seizure requiring further investigation?
Complex febrile seizures are defined by: focal onset, duration >15 minutes, or recurrence within the same febrile illness (within 24 hours). Todd's paresis (post-ictal focal weakness) indicates focal onset, making this a complex febrile seizure requiring EEG and neuroimaging to rule out focal pathology.
Complex febrile seizures: focal OR >15 minutes OR recur within 24 h of same illness. Risk of subsequent epilepsy: simple febrile seizures ~1-2% (baseline); complex febrile seizures ~5-10% depending on features. EEG and MRI are indicated for complex type. Prophylactic AED not routinely recommended even for recurrence.
A 10-minute generalised seizure during first febrile illness is simple if generalised and only one episode. Onset at 18 months is in the normal febrile seizure age range (6 months to 5 years). Recurrence in a different febrile illness months later does not make a febrile seizure complex — it is a separate simple febrile seizure episode.
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A CSF sample is obtained from a 4-year-old child with suspected meningitis. The sample appears xanthochromic (yellow), TLC is 60 cells/mm³ (60% RBCs, 40% lymphocytes), glucose 45 mg/dL (blood glucose 85 mg/dL), protein 90 mg/dL. Which interpretation is MOST correct?
Xanthochromia (yellow discolouration of CSF supernatant) results from oxyhaemoglobin and bilirubin breakdown after RBC lysis — it indicates that red blood cells have been in the CSF long enough to lyse, distinguishing true haemorrhagic CSF from a traumatic tap. In a traumatic tap, the supernatant is clear even if RBCs are present, and RBC count decreases from tube 1 to tube 3.
Key CSF interpretation skills: (1) xanthochromia = true CNS haemorrhage vs traumatic tap; (2) glucose ratio thresholds: <0.4 bacterial, <0.3 TBM/fungal, >0.5 viral; (3) cell differential: neutrophilic = bacterial (early), lymphocytic = viral/TBM/fungal. Lumbar puncture: indications include suspected meningitis/encephalitis, SAH (when CT is negative); contraindications include raised ICP with papilloedema, coagulopathy, posterior fossa lesion.
Traumatic tap: clear supernatant, RBC count decreases from tube 1 to tube 3, no xanthochromia. True subarachnoid/intraventricular haemorrhage: xanthochromic supernatant even after centrifugation, uniform RBC count in all tubes. Bacterial meningitis has neutrophilic pleocytosis, very low glucose — not this picture.
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During lumbar puncture on a 3-year-old child, you aspirate clear CSF. The opening pressure on manometry is 250 mmH₂O. Which of the following is the CORRECT interpretation and action?
Normal CSF opening pressure in children (sitting/lying): 60-200 mmH₂O (lateral decubitus); some sources accept up to 250 mmH₂O in obese individuals. At 250 mmH₂O with an alert/appropriate clinical context, this is elevated. Correct action: collect minimum required CSF (for essential tests) then treat raised ICP (mannitol, head elevation, fluid restriction) rather than removing large volumes, which risks tonsillar herniation.
LP indications: meningitis, SAH (CT-negative), pseudotumour cerebri. Contraindications: raised ICP with papilloedema, posterior fossa lesion (risk of coning), coagulopathy, local infection at site. Technique: L3-L4 or L4-L5 interspace (below conus at L1-L2), measure opening pressure, collect 0.5-1 mL per tube for sequential analysis.
Normal CSF opening pressure in children is 60-200 mmH₂O; 250 mmH₂O is elevated. Removing large volumes of CSF when pressure is elevated can precipitate brainstem herniation — this is dangerous. Pressure measurement is meaningful and should always be recorded.
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