Epilepsy syndromes with partial seizures

I. Introduction and Classification (ILAE 2017)

Focal epilepsies are characterized by seizures originating within networks limited to one hemisphere. They may be discrete (localized) or more widely distributed.
Classification by Etiology/Prognosis:

1. Self-Limiting (Benign) Focal Epilepsies of Childhood: Age-dependent, genetic predisposition, normal MRI, excellent prognosis.
2. Symptomatic (Structural/Metabolic) Focal Epilepsies: Associated with lesions (MTS, tumors, cortical dysplasia), variable prognosis.
3. Genetic/Familial Focal Epilepsies: Autosomal dominant inheritance (e.g., ADNFLE).
4. Epileptic Encephalopathies with Focal Features: e.g., Rasmussen’s, CSWS.

II. Self-Limiting (Benign) Focal Epilepsies

These are the most common childhood epilepsy syndromes (15–25% of pediatric epilepsy).

1. Benign Epilepsy with Centrotemporal Spikes (BECTS) / Rolandic Epilepsy

• Age of Onset: 3–13 years (Peak: 7–9 years).
• Clinical Features:
  • Timing: 75% occur during NREM sleep (shortly after falling asleep or before waking).
  • Semiology: Unilateral sensorimotor symptoms involving the face, tongue, and pharynx.
  • Symptoms: Oropharyngeal paresthesia ("numbness inside cheek"), guttural sounds, drooling (sialorrhea), speech arrest (anarthria). May evolve into hemifacial motor clonic jerks or focal-to-bilateral tonic-clonic seizures (GTCS).
  • Neurology: Normal exam; normal development.
• EEG Features (Hallmark):
  • Interictal: High-voltage, blunt, biphasic spikes in the centrotemporal (Rolandic) region (C3/C4, T3/T4).
  • Dipole: Horizontal dipole (negativity centrotemporal, positivity frontal).
  • Activation: Prominent activation with sleep.
• Management:
  • Many do not require medication if seizures are infrequent/nocturnal only.
  • First-line (if needed): Carbamazepine, Oxcarbazepine, or Levetiracetam.
• Prognosis: Excellent. Remission by puberty (age 15–16) is the rule.

2. Panayiotopoulos Syndrome (Early Onset Benign Occipital Epilepsy)

• Age of Onset: 3–6 years (Early childhood).
• Clinical Features:
  • Autonomic Status: Prominent autonomic features: Emesis (vomiting is cardinal), pallor, sweating, pupil dilation.
  • Duration: Seizures are often prolonged (>30 mins), mimicking status epilepticus, but non-convulsive.
  • Eye Deviation: Lateral deviation of eyes (open) is common. Visual hallucinations are rare (unlike late-onset).
• EEG: High-amplitude sharp-and-slow wave complexes, often occipital, but can shift locations (multifocal) on serial EEGs ("Fixation-off sensitivity").
• Management: Rescue benzodiazepines for prolonged events. Daily AEDs often not needed due to infrequency.
• Prognosis: Excellent. Remission usually within 1–2 years of onset.

3. Gastaut Type (Late Onset Childhood Occipital Epilepsy)

• Age of Onset: 8–11 years.
• Clinical Features:
  • Visual Aura: Elementary visual hallucinations (multicolored circles, flashes), blindness, or hemianopia.
  • Post-ictal: Severe migraine-like headache.
• EEG: Occipital spikes (O1/O2) that attenuate with eye-opening (Fixation sensitivity).
• Prognosis: Variable; less likely to remit spontaneously compared to Panayiotopoulos.

III. Symptomatic / Structural Focal Epilepsies

1. Temporal Lobe Epilepsy (TLE)

The most common form of focal epilepsy in adolescents and adults.

• Etiology:
  • Mesial Temporal Sclerosis (MTS): Hippocampal atrophy and gliosis. Often history of prolonged febrile seizures in infancy.
  • Tumors (Ganglioglioma, DNET), Cortical Dysplasia.
• Semiology:
  • Aura: Epigastric rising sensation (most common), Déjà vu (familiarity), Jamais vu, fear, olfactory hallucinations (uncinate fits).
  • Ictal: Behavioral arrest (staring), Oro-alimentary automatisms (lip-smacking, chewing), Manual automatisms (picking, fumbling).
  • Post-ictal: Confusion, nose-wiping (ipsilateral to focus), transient aphasia (if dominant hemisphere).
• Investigation:
  • MRI: Hyperintensity on T2/FLAIR in hippocampus; atrophy.
  • EEG: Anterior temporal spikes/sharp waves.
• Management: Often drug-resistant. Surgical resection (Anterior Temporal Lobectomy) is highly effective (70–80% cure).

2. Frontal Lobe Epilepsy (FLE)

• Etiology: Cortical dysplasia (FCD), post-traumatic, tumors.
• Semiology:
  • Hyperkinetic: Bizarre, thrashing movements, pelvic thrusting, cycling leg movements, vocalization (screaming/grunting).
  • Timing: Clusters during sleep (often misdiagnosed as night terrors/parasomnias).
  • Duration: Very brief (<30 seconds) with rapid recovery (minimal post-ictal confusion).
• EEG: Often normal or obscured by muscle artifact.
• Genetics: ADNFLE (Autosomal Dominant Nocturnal Frontal Lobe Epilepsy) – Mutation in nicotinic acetylcholine receptor (CHRNA4).

IV. Specific Etiology-Linked Syndromes

1. Rasmussen’s Encephalitis

• Pathology: Chronic, progressive T-cell mediated autoimmune encephalitis affecting one hemisphere.
• Age: Peak 6–7 years.
• Clinical:
  • EPC: Epilepsia Partialis Continua (continuous focal jerking of a limb/face).
  • Progression: Intractable seizures $\to$ Hemiparesis $\to$ Cognitive decline (dementia).
• MRI: Progressive hemi-atrophy of the affected hemisphere.
• Management: Medical therapy fails. Functional Hemispherectomy is the only curative option.

2. Hypothalamic Hamartoma (Gelastic Epilepsy)

• Lesion: Non-neoplastic heterotopia in the tuber cinereum/hypothalamus.
• Clinical:
  • Gelastic Seizures: Mirthless, mechanical laughter (often starts in infancy).
  • Dacrystic Seizures: Crying seizures.
  • Comorbidity: Central Precocious Puberty.
• Management: Surgical disconnection or Stereotactic Radiosurgery (Gamma Knife).

3. Sturge-Weber Syndrome

• Pathology: Leptomeningeal angiomatosis.
• Clinical: Focal motor seizures contralateral to Port-Wine Stain.
• Course: Seizures often start in infancy, leading to hemiparesis and calcification (tram-track sign).

V. Acquired Epileptic Aphasia (Landau-Kleffner Syndrome)

• Nature: An epileptic encephalopathy with focal EEG features but global cognitive impact.
• Clinical: Normal early development $\to$ Subacute onset of Verbal Auditory Agnosia ("Word deafness") $\to$ Loss of speech.
• Seizures: Infrequent focal motor seizures (25% have no clinical seizures).
• EEG: CSWS (Continuous Spike and Waves during Sleep). >85% of slow-wave sleep occupied by discharges, usually temporal/parietal.
• Treatment: Steroids (high dose), IVIG, Benzodiazepines.

VI. Management Summary