A 63‑year‑old man with type 2 diabetes mellitus, hypertension and a remote right‑hemispheric ischemic stroke presents with one week of altered sleep and behavior and one day of new‑onset gait difficulty; laboratory studies show normal renal and liver function tests, mildly elevated alkaline phosphatase, borderline low albumin, modestly raised erythrocyte sedimentation rate, hemoglobin 13.1 g/dL, leukocyte count 8.9 ×10⁹/L, platelet count 369 ×10⁹/L; non‑contrast CT of the head reveals chronic encephalomalacia with gliosis in the right cerebral hemisphere and age‑related cerebral atrophy; abdominal ultrasound shows cholelithiasis, bilateral mild renal cortical echogenicity and a small right hydronephrosis; ophthalmology evaluation shows no papilledema. What are the likely differential diagnoses and immediate management steps?

Differential Diagnoses and Immediate Management

This patient requires urgent exclusion of metabolic encephalopathy (particularly hypoglycemia), infectious/inflammatory CNS disease (including tuberculous meningitis given family history), and recurrent stroke, with immediate bedside glucose testing, lumbar puncture, and MRI with diffusion-weighted imaging as the highest priorities.

Most Likely Differential Diagnoses

1. Metabolic Encephalopathy

• Hypoglycemia is the most critical immediate consideration, as it can produce focal neurological deficits indistinguishable from acute stroke and causes permanent brain damage if untreated 1, 2
• Despite "normal glycemic control currently," patients with poorly controlled diabetes (HbA1c 12%) may experience hypoglycemic symptoms at higher glucose thresholds 1
• Hypoglycemia directly mimics stroke with altered sensorium, focal weakness, and gait difficulty 2, 3
• Uremic encephalopathy is less likely given normal KFT, but mild right hydronephrosis warrants monitoring 2

2. CNS Infection (Tuberculous Meningitis)

• Both parents had pulmonary tuberculosis 20 years ago, creating significant exposure risk 4
• Subacute presentation (1 week behavioral changes, 1 day gait difficulty) fits tuberculous meningitis timeline better than acute stroke 4
• Elevated ESR (23) and mildly elevated ALP (122) with borderline low albumin (3.66) suggest chronic inflammatory process 4
• Absence of papilledema does not exclude meningitis 4

3. Recurrent Ischemic Stroke

• History of right hemispheric stroke 2 years ago with persistent risk factors (uncontrolled diabetes HbA1c 12%, hypertension) 4
• Diabetic patients have 2-6 times higher stroke risk, magnified by poor glycemic control 5, 6
• However, NCCT shows only old changes (encephalomalacia/gliosis), not acute findings 4
• Subacute behavioral changes over 1 week are atypical for acute stroke 4

4. Diabetic Striatopathy

• Rare complication of severe hyperglycemia causing movement disorders and altered mental status 7
• Can present with progressive involuntary movements and gait difficulty 7
• Requires CT showing striatal hyperdensity for diagnosis 7

5. Hepatic Encephalopathy

• Cholelithiasis on ultrasound raises concern, though LFT is normal except mildly elevated ALP 4
• Less likely given normal bilirubin and transaminases 4

Immediate Management Steps (First 30 Minutes)

Critical Bedside Testing

• Perform finger-stick glucose immediately without waiting for laboratory results 2, 3
• If glucose <70 mg/dL, administer 25 mL of 50% dextrose via slow IV push immediately 1, 2, 3
• Recheck glucose after 15 minutes; repeat dextrose if hypoglycemia persists 1

Vital Signs and Monitoring

• Measure blood pressure in both arms to assess for asymmetry suggesting large vessel involvement 4
• Continuous cardiac monitoring to detect atrial fibrillation (major stroke risk factor) 4, 2
• Check oxygen saturation; provide supplemental oxygen only if hypoxic 2
• Measure temperature; treat fever >37.5°C as it worsens neurological outcomes 2

Laboratory Investigations

• Comprehensive metabolic panel (sodium, potassium, calcium, glucose, creatinine) to identify metabolic stroke mimics 3
• Complete blood count with differential (current WBC 8.9 is normal but trend matters) 4
• Repeat ESR and CRP (ESR 23 suggests inflammation) 4
• Hemoglobin A1c already known at 12% 4
• Blood cultures if febrile 4

Urgent Diagnostic Studies (Within 2-4 Hours)

Neuroimaging

• MRI brain with diffusion-weighted imaging (DWI) is superior to CT for detecting acute ischemia 4, 7
• DWI will distinguish acute infarction from chronic encephalomalacia 7
• T1-weighted images can identify diabetic striatopathy (striatal hyperintensity) 7
• MR angiography to assess for large vessel stenosis or occlusion 4

Lumbar Puncture (High Priority)

• Mandatory given TB exposure history and subacute presentation 4
• Perform after neuroimaging confirms no mass effect or midline shift 4
• Send CSF for: cell count with differential, protein, glucose, Gram stain, acid-fast bacilli stain and culture, TB PCR, cryptococcal antigen 4
• Opening pressure measurement essential 4

Additional Vascular Studies

• Carotid duplex ultrasound to assess for stenosis (given stroke history) 4
• Echocardiogram to evaluate for cardioembolic source 4

Glucose Management Protocol

Target Range

• Maintain blood glucose 140-180 mg/dL for hospitalized stroke patients 4, 2, 3
• This range balances hypoglycemia risk against hyperglycemia complications 2, 3

Monitoring Frequency

• Check glucose every 1-2 hours initially 2
• Continue frequent monitoring throughout acute phase as both hyper- and hypoglycemia predict poor outcomes 3, 5

Insulin Administration

• Initiate insulin therapy if glucose >200 mg/dL 4
• Use basal-bolus insulin regimen, not sliding-scale alone 1
• Avoid aggressive lowering to <140 mg/dL as this increases hypoglycemia risk without benefit 2

IV Fluid Selection

• Use normal saline at 75-100 mL/h to maintain normovolemia 2, 3
• Never use dextrose-containing fluids (D5W) as hyperglycemia worsens stroke outcomes 4, 2, 3

Blood Pressure Management

Thresholds

• Do not treat hypertension unless systolic BP >220 mmHg or diastolic BP >120 mmHg 2
• Precipitous BP lowering can extend infarction 2
• Correct hypotension if present (systolic <100 mmHg) with normal saline and treat underlying causes 4

Common Pitfalls to Avoid

Diagnostic Errors

• Do not attribute all symptoms to old stroke without excluding acute metabolic, infectious, or vascular causes 3, 7
• Do not overlook TB meningitis in patients with family TB exposure and subacute neurological decline 4
• Do not assume normal CT excludes acute stroke; MRI with DWI is required 4, 7

Management Errors

• Do not delay glucose testing while awaiting other studies—hypoglycemia causes irreversible brain injury 1, 2, 3
• Do not use hypotonic solutions for any indication as they exacerbate cerebral edema 1
• Do not aggressively lower glucose to <140 mg/dL 2
• Do not delay lumbar puncture if TB meningitis is suspected—early treatment is critical 4

Risk Stratification for Secondary Prevention

High-Risk Features Present

• Uncontrolled diabetes (HbA1c 12%) increases stroke risk 2-6 fold 5, 6
• History of prior stroke with persistent vascular risk factors 4
• Hypertension inadequately controlled 4
• Elevated ESR suggesting ongoing inflammation 4

Long-Term Monitoring Priorities

• Diastolic blood pressure and fasting blood glucose during follow-up are key prognostic determinants 8
• Physical activity and lipid-lowering treatment negatively correlate with poor outcomes 8
• Monitor for development of diabetic complications (nephropathy, retinopathy) 4