Focal Seizures

Definition & Classification

1. Awareness — intact vs. impaired at any point during the seizure
2. Onset type — motor vs. nonmotor

ILAE 2017 Classification of Seizure Types — Goldman-Cecil Medicine

Types

1. Focal Aware Seizures (FAS)

• Motor onset: contralateral tonic, clonic, or myoclonic activity
• Sensory: paresthesias, visual phenomena, auditory sounds, vertigo, olfactory (acrid smell) or gustatory (metallic/bitter taste)
• Autonomic: flushing, sweating, piloerection, epigastric rising sensation
• Cognitive/emotional: déjà vu, fear, depersonalization, dreamlike states

2. Focal Impaired Awareness Seizures (FIAS)

• Begins with a motionless stare
• Automatisms: lip smacking, chewing, swallowing, picking/wringing hand movements, or more elaborate behaviors (emotional display, running)
• Patient is typically disoriented post-ictally; transition to full recovery may take seconds to hours
• Postictal deficits may include anterograde amnesia, aphasia, hemi-neglect, or visual loss from cortical inhibition
• Duration typically 30 seconds to 2 minutes — Harrison's Principles of Internal Medicine 22E

3. Focal to Bilateral Tonic-Clonic Seizures

• A focal seizure spreads to engage both hemispheres, evolving into tonic-clonic activity
• Most common when the focus is in the frontal lobe
• The focal onset is often missed by bystanders, who describe only the dramatic convulsive phase
• Distinguishing this from primary generalized onset has major treatment and prognostic implications

Localization by Seizure Type

Special Phenomena

Jacksonian March

Todd's Paralysis

Epilepsia Partialis Continua

Focal Status Epilepticus

EEG Features

• Interictal EEG may be normal or show focal epileptiform spikes/sharp waves
• Ictal EEG: rhythmic localized discharge (often 4–7 Hz), increasing in amplitude and decreasing in frequency as the seizure progresses
• Seizures from medial temporal or inferior frontal regions may be non-localizing on scalp EEG → intracranial electrode placement may be needed
• Focal slowing on EEG suggests localized parenchymal dysfunction — Harrison's / Kaplan & Sadock's Synopsis

Etiologies

• Structural: brain tumor, cortical dysplasia, post-traumatic scar, vascular malformation (AVM, cavernoma), stroke, hippocampal sclerosis
• Metabolic: hyperosmolar states (focal seizures common in hyperosmolar coma), uremia
• Infectious/inflammatory: encephalitis, abscess
• Genetic: certain focal epilepsy syndromes (e.g., KCNT1-related epilepsy)

Treatment

First-Line Anti-Seizure Medications (ASMs) for Focal Epilepsy

Surgical Treatment

Clinical Pearls

1. Always ask about a warning — missing the aura/focal onset leads to misclassification as primary generalized epilepsy, with implications for drug choice and workup.
2. Bizarre or stereotyped episodic behavior should prompt EEG evaluation before ruling out seizures.
3. Focal onset implies structural disease until proven otherwise — MRI brain is mandatory.
4. Distinguishing focal from generalized onset is essential: certain ASMs (e.g., carbamazepine) can worsen generalized epilepsies. — Harrison's Principles of Internal Medicine 22E

Alcohol Withdrawal Syndrome (AWS)

Pathophysiology

Clinical Progression

Withdrawal may begin before blood alcohol levels reach zero and can last up to 4–6 months as a protracted abstinence syndrome. — Maudsley Prescribing Guidelines, 15th ed.

Clinical Stages in Detail

1. Minor (Uncomplicated) Withdrawal

• Tremor (hands, tongue, eyelids), irritability, anorexia, nausea, tachycardia, diaphoresis, hypertension, hyperreflexia, vivid dreams
• Usually resolves within 48 hours
• Management: supportive care, hydration, vitamins

2. Alcoholic Hallucinosis

• Visual and auditory hallucinations (more accurately illusions — patients retain reality testing and intact sensorium)
• Onset 8–48 hours after cessation
• Distinguished from DTs by the clear sensorium — The Washington Manual of Medical Therapeutics

3. Withdrawal Seizures

• Typically one or a few brief generalized tonic-clonic convulsions
• Onset 12–48 hours (peak ~24 hours); can occur up to 5 days post-cessation
• May occur in the absence of other signs of withdrawal
• About 2% of individuals with alcohol use disorder experience withdrawal seizures; risk increases with older age, comorbidities, polydrug use, and higher alcohol intake
• Routine AEDs (antiepileptics) are not indicated for typical alcohol withdrawal seizures; treat with benzodiazepines
• Phenytoin does not prevent alcohol withdrawal seizures — Maudsley; Washington Manual
• If seizures occur despite adequate benzodiazepine loading, carbamazepine can be considered

4. Delirium Tremens (DTs)

• Develops in 3–5% of those admitted for withdrawal; appears ~72–96 hours after last drink
• Life-threatening — mortality 10–20% if untreated, ~5% with proper ICU management
• Features: profound confusion + agitation + marked tremor + vivid hallucinations (especially visual and tactile) + severe autonomic hyperactivity:
  • Fever > 38.5°C
  • BP > 140/90 mmHg
  • Tachycardia, diaphoresis
  • Paranoid delusions
• Often runs a course of 3–5 days regardless of treatment

DSM-5 Diagnostic Criteria

• Cessation or reduction of heavy, prolonged alcohol use
• ≥2 of the following within hours to days:
  • Autonomic hyperactivity
  • Hand tremor
  • Insomnia
  • Nausea or vomiting
  • Transient hallucinations or illusions
  • Psychomotor agitation
  • Anxiety
  • Generalized tonic-clonic seizures

Assessment: CIWA-Ar Scale

• Nausea/vomiting
• Tremor
• Paroxysmal sweats
• Anxiety
• Agitation
• Tactile disturbances (formication — "bugs crawling under skin")
• Auditory/visual disturbances
• Headache
• Orientation/clouding of sensorium

• ≤10: mild — monitor, may not need pharmacotherapy
• 10–15: moderate — initiate pharmacotherapy
• >15: severe — urgent pharmacological treatment
• Max possible score: 67

Management

Step 1 — Immediate Assessment

• Full physical exam: liver disease, GI bleeding, arrhythmias, infection, hypoglycemia, electrolyte imbalances
• Avoid IV fluids unless clear indication (most patients are normohydrated or overhydrated)

Step 2 — Thiamine First

• Thiamine 100–500 mg IM/IV before any glucose (to prevent precipitating Wernicke's encephalopathy)
• Then 100 mg PO daily × ≥1 week
• Multivitamins with folic acid

Step 3 — Pharmacotherapy

Benzodiazepines — First-line

• Long-acting benzodiazepines (diazepam, chlordiazepoxide) are preferred for seizure prophylaxis — their self-tapering pharmacokinetics reduce the risk of breakthrough seizures
• Symptom-triggered protocols are superior to fixed-dose schedules

Delirium Tremens — ICU Management

• High-dose benzodiazepines (up to 800 mg/day chlordiazepoxide reported)
• Refractory DTs: propofol or closely monitored dexmedetomidine as adjuncts
• Dexmedetomidine alone is not adequate — it does not target GABA/glutamate systems, can mask autonomic signs without preventing seizures, and has not improved outcomes in trials
• Antipsychotics are not recommended for AWS (do not address underlying mechanism; lower seizure threshold)
• Correct hypomagnesemia, hypokalemia, hypoglycemia — Washington Manual; Harrison's

Step 4 — Phenobarbital (Adjunct/Alternative)

Setting of Care

Community/Outpatient Detox — Suitable when:

• Mild symptoms with good social support and 24-hour supervision
• No prior DTs or withdrawal seizures
• Regular consumption <30 units/day, SADQ <30
• Daily medication pickup and professional review feasible

Inpatient Detox — Required when:

• Regular consumption >30 units/day or SADQ >30
• History of seizures or DTs
• Concurrent benzodiazepine use or polysubstance use
• Comorbid physical or psychiatric illness
• Pregnancy, minors, elderly
• Homeless or no social support
• Failed community detox — Maudsley Prescribing Guidelines

Electrolyte & Nutritional Considerations

• Hypomagnesemia (lowers seizure threshold)
• Hypokalemia
• Hypoglycemia
• Hypophosphatemia
• Thiamine deficiency (→ Wernicke's encephalopathy if glucose given first)

Key Clinical Pearls

1. Only reduction in intake is needed to trigger withdrawal — patients can be in AWS while still drinking.
2. Previous AWS episodes predict future severity (kindling effect — each withdrawal lowers the seizure threshold).
3. The most important risk factor for AWS in hospitalized patients is a prior history of withdrawal episodes.
4. Phenytoin is ineffective for alcohol withdrawal seizures — do not use it.
5. Antipsychotics treat hallucinations but do not prevent seizures and can lower seizure threshold — use with caution only as adjuncts to benzodiazepines.
6. DTs can skip the usual progression and present without prior mild symptoms.