Initial evaluation

History with special attention to medications (including over-the-counter and herbals)

General physical examination and neurologic examination

Complete blood count

Electrolyte panel including calcium, magnesium, phosphorus

Liver function tests, including albumin

Renal function tests

First-tier further evaluation guided by initial evaluation

Systemic infection screen

Urinalysis and culture

Chest radiograph

Blood cultures

Electrocardiogram

Arterial blood gas

Serum and/or urine toxicology screen (perform earlier in young persons)

Brain imaging with MRI with diffusion and gadolinium (preferred) or CT

Suspected CNS infection: lumbar puncture after brain imaging

Suspected seizure-related etiology: EEG (if high suspicion, should be performed immediately)

Second-tier further evaluation

Vitamin levels: B₁₂, folate, thiamine

Endocrinologic laboratories: TSH and free T₄; cortisol

Serum ammonia

Sedimentation rate

Autoimmune serologies: ANA, complement levels; p-ANCA, c-ANCA. consider paraneoplastic serologies

Infectious serologies: RPR; fungal and viral serologies if high suspicion; HIV antibody

Lumbar puncture (if not already performed)

Brain MRI with and without gadolinium (if not already performed)