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Benign Occipital Seizure


Benign Occipital Seizure

Article Author:
Prabhu Emmady
Article Editor:
Joe M Das
Updated:
10/13/2020 11:38:41 AM
For CME on this topic:
Benign Occipital Seizure CME
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Benign Occipital Seizure

Introduction

Benign occipital seizures are classified as an occipital onset epilepsy syndrome, which occurs in children with normal developmental milestones, normal general and neurological examination, and without any structural abnormalities in the brain. These seizures are limited to childhood-onset only. Under the International league against epilepsy (ILAE) classification, this is classified under childhood epilepsy syndromes. These are rare conditions with a very low incidence; however, their exact incidence is unclear.[1] These epilepsies are broadly classified into 2 categories based on their clinical presentation. Children with Panayiotopoulos syndrome (PS) have autonomic symptoms, while children with idiopathic childhood occipital epilepsy of Gastaut (ICOE-G) have visual symptoms.[2][3] A small number of patients with this syndrome cannot be placed in either of these 2 categories.[4]

Etiology

Benign occipital seizures are believed to have a genetic basis. While a specific genetic abnormality has not been identified, the genetic basis is felt to be complex and polygenic.[5] SCN1A mutations were reported in a phenotype of PS, which causes severe symptoms.[6] No specific genetic or chromosomal abnormalities have been identified for ICOE-G. Most children with these seizures do not have siblings or family members with similar seizures. Family history of febrile seizures, other epilepsy syndromes, and migraines are seen in a small number of patients.[7]

Epidemiology

PS: This condition typically presents in children between the ages of 3-6 years, though it can present from 1 to 14 years of age.[8] The majority of children with this condition do not have more than 6 seizures in their lifetime; half of these only have one seizure.

ICOE-G: This condition typically presents in children between the ages of 1-18 years. In more than half the patients, seizures resolve within 4 years of onset.[9]

Pathophysiology

Multifocal cortical hyperexcitability is seen in children with PS. This is felt to be maturation related, and the location of the spikes often shifts with time. These epileptic discharges activate autonomic centers and result in the autonomic symptoms noted during the seizures. Due to the activation of the central autonomic network, tachycardia, hypertension, and vasopressin release may be noted.[10]

History and Physical

PS

Seizures are characterized as autonomic seizures and are the hallmark of this syndrome. While nausea and vomiting are the most common presentations, other presentations include pallor, mydriasis, thermoregulatory changes, cardiorespiratory changes, incontinence, hypersalivation, etc. Generalized status epilepticus is extremely uncommon.[7] Seizures can often present as focal autonomic status epilepticus, as symptoms last more than 30 minutes.[11] Seizures are not always stereotypical, and autonomic features may be the only symptoms during a seizure. Children are normal between seizures, and sleep often helps in restoring the child to become normal. 

This clinical condition is relatively difficult to diagnose and requires strong clinical suspicion and expertise. Due to the atypical presentations, diagnosis is often delayed, and the seizures are often misdiagnosed as non-epileptic seizures, migraines, vertiginous attacks, sleep disorders, etc.

ICOE-G

Seizures are characterized by visual symptoms and are the hallmark of this syndrome. The symptoms may include visual hallucinations, ictal blindness, orbital pain, headache, nausea, or vomiting. When symptoms spread beyond the occipital lobe, patients may exhibit focal sensory or motor symptoms. Seizures may be very frequent in some children and can be seen daily without treatment.[9] Headache is common and seen in about one-third of patients, often during the postictal state. 

This clinical condition is often misdiagnosed as a migraine due to a similar presentation of visual symptoms and headaches.

Evaluation

Establishing a diagnosis of benign occipital epilepsy involves a detailed history and characteristic electroencephalogram (EEG) findings. Imaging studies, including magnetic resonance imaging (MRI), are normal and help differentiate these from secondary epilepsy syndromes. These are not always necessary but can be done to rule out symptomatic occipital epilepsy. Comprehensive neurological examination and developmental assessment are also normal.

EEG findings are characterized by focal occipital paroxysmal interictal discharges, though more than 50% of patients may have diffuse or multifocal epileptiform activity, with occipital predominance.[4] Epileptiform abnormalities include spikes, spike, and waves, multiple spike and waves intermixed with slow waves, multifocal spikes. As in most patients with epilepsy, several routine EEGs may be normal. Hence prolonged EEG monitoring either with ambulatory EEG or inpatient video EEG monitoring is recommended when outpatient routine EEGs are non-diagnostic. 

The magnetoencephalographic study revealed spikes in frontal, Rolandic, parietooccipital, and calcarine sulci. Localized hyperexcitability was seen in the areas along the major cortical sulci.[12] Follow up imaging revealed shifting spikes indicating that the captured spikes do not represent the seizure semiology but rather indicate maturation-related cortical hyperexcitability.[13] In ICOE-G, epileptic encephalopathy with continuous spike-and-wave during sleep may be present, hence sleep EEG has a very high yield.[14]

Treatment / Management

Antiepileptic medications are generally not recommended for seizures, which are brief, infrequent, or in patients who have less than 2 seizures. Antiepileptic treatment is usually reserved for children with a high risk of recurrence. Rescue benzodiazepines may remain the treatment of choice in children with for children with PS as more than half the patients with this condition have the risk of autonomic status epilepticus but a low risk of frequent, prolonged seizures.

In ICOE-G, children may have frequent seizures requiring antiepileptic medications. Carbamazepine has more than 90% clinical response and is the first-line medication in such children. Other medication options include sodium valproate and phenobarbital.[15] The need for continuation of antiepileptic medications must be reassessed during every clinic visit. Most children do not require antiepileptic medications beyond 2 to 3 years.

Differential Diagnosis

Differential diagnoses include:

  • Benign epilepsy with centrotemporal spikes (BECTS)
  • Disorders associated with intermittent vomiting
  • Idiopathic photosensitive occipital lobe epilepsy (IPOLE)
  • Infectious encephalitis
  • Metabolic encephalopathy
  • Migraine
  • Occipital lobe epilepsy secondary to structural abnormalities
  • Syncope

BECTS is a common epilepsy syndrome in children. It is the only other benign focal epilepsy syndrome in children. Similar to benign occipital seizures, children with BECTS have a very good prognosis and have normal development and MRI. The seizures originate from the centrotemporal area, located around the Rolandic fissure.[16]

IPOLE is a type of reflex epilepsy. Seizures are induced by light stimulation, such a flickering. Seizures may start between the ages of 5 to 17 years. At the seizure onset, the child often has elementary visual symptoms. Headache, abdominal pain, nausea, vomiting may follow. Impairment of consciousness may or may not occur.[17]

Prognosis

As the word benign implies, they often have a good prognosis and most children do not require treatment. The children do not have any residual neurological deficits after epilepsy resolves. There is no increased risk of epilepsy in adulthood.

Complications

Complications are rare in children with benign occipital seizures. Children with ICOE-G are unlikely to have significant complications. In children with PS, autonomic status epilepticus may increase the risk of cardiorespiratory arrest. A higher risk of respiratory depression may occur when using standard rescue benzodiazepine dosages in patients with autonomic status epilepticus, hence reduced dosage need to be considered.[18]

Deterrence and Patient Education

Counseling of side effects, compliance, drug interactions, etc., must be performed during every clinic visit as these may change over time. Parents must be educated and counseled that the outcome with benign occipital seizures is excellent, and the seizures resolve before adulthood, and children have no residual neurological deficits.

Enhancing Healthcare Team Outcomes

Benign occipital seizures are not very common, but it is very important to be recognized by all healthcare workers, including pediatricians and nurses who work with children. Since the symptoms like nausea, vomiting, blindness, pallor, hypersalivation are atypical for seizures, referral to a neurologist for neurodiagnostic workup is not generally obtained. Education of this condition can help early identification of children with these stereotypical events. 

An interprofessional approach is recommended when treating a child with Benign occipital seizures. Some children do not need daily medication but will need rescue medication, and education about this must be provided to the school nurse, parents, and family members. Pharmacists can help with this. Pharmacists can also help with educating the children and their parents about the side effects and the importance of compliance of medications.


References

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