What are the types of occipital epilepsy in children?

Types of Occipital Epilepsy in Children

Childhood occipital epilepsies are primarily classified into two distinct idiopathic syndromes: early-onset Panayiotopoulos syndrome (an autonomic epilepsy) and late-onset Idiopathic Childhood Occipital Epilepsy of Gastaut (ICOE-G), which differ fundamentally in their clinical presentation, age of onset, and prognosis. 1, 2

Primary Classification

1. Panayiotopoulos Syndrome (Early-Onset Benign Occipital Epilepsy)

• Age of onset: Typically between 3-7 years 2
• Seizure characteristics:
  • Nocturnal seizures with tonic deviation of the eyes followed by vomiting 3
  • Brief, infrequent attacks or prolonged status epilepticus 2
  • Ictal deviation of eyes and/or head with prominent autonomic features 2
  • Visual symptoms may be present when patients awaken from sleep 3
• Key distinguishing feature: This is fundamentally an autonomic epilepsy rather than a purely visual epilepsy 1, 2
• Prognosis: Benign with good response to treatment 1

2. Idiopathic Childhood Occipital Epilepsy of Gastaut (ICOE-G) (Late-Onset)

• Age of onset: Typically 7-10 years, occurring during wakefulness 3, 4
• Seizure characteristics:
  • Episodes begin with visual symptoms (elementary visual hallucinations) 3, 2
  • Followed by loss of consciousness but typically no generalized convulsions 3
  • May progress to hemiclonic seizures, complex partial seizures, or generalized tonic-clonic seizures 3
  • Frequently followed by postictal headache 2
• EEG findings: Bilateral occipital spike-wave activated by eye closure ("fixation-off" phenomenon) 4, 2
• Prognosis: Can show atypical evolution and potential refractoriness to treatment 1
• Important caveat: May evolve to include typical absence seizures in some patients 4

Symptomatic Occipital Epilepsies

Beyond the idiopathic syndromes, several structural causes must be recognized 5:

Malformations of Cortical Development

• Focal cortical dysplasia 5
• Periventricular heterotopia (PVH) 5
• Subcortical band heterotopia (SBH) 5
• Polymicrogyria 5

Vascular Causes

• Epilepsy with bilateral occipital calcifications (often associated with celiac disease) 5

Metabolic Causes

• Various metabolic disorders affecting the occipital cortex 5

Critical Diagnostic Considerations

Visual hallucinations are the key clinical symptom indicating an occipital focus, but they are frequently difficult to elicit from children and may not always be present. 5

Diagnostic Pitfalls to Avoid:

• When visual symptoms are not prominent, seizure semiology and scalp EEG often reflect seizure propagation rather than origin, leading clinicians away from considering an occipital focus 5
• Seizure symptomatology remains crucial for diagnosis even when EEG appears normal 3
• Some patients may have independent centro-temporal spikes or generalized spike-wave discharges in addition to occipital spikes, suggesting the idiopathic nature of these epilepsies 3

Imaging Recommendations

Several seizure syndromes including benign occipital epilepsy with classic EEG findings are sufficiently characteristic to be diagnosed clinically or through specific EEG patterns and usually do not require imaging. 6

• Patients who may benefit from imaging include those who do not have typical clinical or EEG findings 6
• MRI is superior to CT for detecting occipital epileptogenic lesions, with functional neuroimaging (PET) showing better performance than SPECT in defining epileptogenic zones when MRI is normal 6

Relationship to Other Epilepsy Syndromes

• Benign occipital and benign rolandic epilepsy are commonly associated with migraine 2
• The association between benign occipital epilepsy and migraine is likely related to underlying mechanisms of selective occipital lobe involvement 2
• Clinical and/or EEG manifestations of other forms of idiopathic partial or generalized epilepsy may be found in association 2

Treatment Implications

• Where medical therapy is ineffective, occipital corticectomy should be considered, with emerging evidence suggesting good surgical outcomes and potentially less severe consequences to visual function than anticipated 5
• Some syndromes now have specific treatments based on their underlying etiology 5
• ICOE-G specifically may show refractoriness to treatment and requires closer monitoring 1