What is the initial management for a patient with EEG findings of lateralized periodic discharges (LPDs)?

From the Guidelines

The initial management for a patient with lateralized periodic discharges (LPDs) on EEG should focus on identifying and treating the underlying cause while monitoring for seizures, with urgent neuroimaging and comprehensive labs being the first steps. According to the American Clinical Neurophysiology Society Criteria for Electrographic Seizures, Status Epilepticus, and Ictal-Interictal Continuum, as outlined in the 2023 American Heart Association focused update 1, LPDs are considered part of the ictal-interictal continuum, which may represent an increased risk of seizures. Key considerations in managing LPDs include:

• Obtaining urgent neuroimaging, preferably MRI brain, to evaluate for structural lesions such as stroke, tumor, or encephalitis
• Checking comprehensive labs including electrolytes, glucose, complete blood count, liver and kidney function, toxicology screen, and considering lumbar puncture if infection is suspected
• Administering antiseizure medications such as levetiracetam or valproate for patients with clinical seizures accompanying LPDs, with dosing guided by clinical context and patient response
• Implementing continuous EEG monitoring for at least 24-48 hours to detect subclinical seizures or evolution to status epilepticus, as LPDs are associated with a high risk of seizures and may represent an ictal-interictal continuum, as noted in the criteria outlined by Hirsch et al. 1.

From the Research

Initial Management for Lateralized Periodic Discharges (LPDs)

The initial management for a patient with EEG findings of lateralized periodic discharges (LPDs) involves careful consideration of the clinical context and EEG patterns. Key points to consider include:

• The distinction between interictal, ictal, and peri-ictal LPDs, as proposed by 2
• The recognition of LPDs-plus, which include spiky or sharp LPDs followed by associated slow after-waves or periods of flattening, giving rise to a triphasic morphology 2
• The identification of LPDs-max, a subtype of LPDs-plus that corresponds to an ictal pattern and focal non-convulsive status epilepticus 2

EEG Monitoring and Seizure Risk

Continuous EEG monitoring is essential for detecting seizure activity, particularly in patients with LPDs. Studies have shown that:

• Higher LPD amplitude is associated with increased risk of seizures on an individual patient level 3
• LPDs with plus features, such as rhythmicity, overlying fast frequencies, or sharply contoured morphology, are more likely to be associated with seizures 3, 4
• The presence of LPDs, even in the absence of acute or progressive brain injury, is independently associated with abnormal consciousness, functional decline, and worse outcome at hospital discharge 5

Clinical Approach

A global clinical approach, considering both clinical and neuroimaging data, is necessary for interpreting EEGs in critically ill patients. This approach should include:

• Careful evaluation of the clinical context and EEG patterns to distinguish between interictal, ictal, and peri-ictal LPDs 2
• Consideration of the electrographic features of LPDs, such as morphology, frequency, and rhythmicity, to stratify risk in the interictal-ictal continuum 4
• Close monitoring for seizure activity and adjustment of treatment accordingly 6