Diagnosis and Investigations for Epilepsy

Detailed Clinical History:

• Assessment includes the frequency, symptoms, duration, and possible triggers of each seizure episode, as well as any associated or underlying neurological conditions.
   

Neuroimaging:

• Magnetic Resonance Imaging (MRI)

  • Brain MRI plays a vital role in the diagnosis and management of epilepsy, offering several key advantages:

  • MRI provides detailed three-dimensional (3D) images of cerebral vasculature and brain structures, allowing for the precise detection and localisation of even minute (as small as a few millimetres) abnormalities and structural lesions that may constitute the epileptogenic focus — the region of the brain where seizures originate.

  • Examples include cortical malformations, scar tissue, tumours, vascular abnormalities, and structural changes arising from trauma or infection, all of which can be accurately identified.

  • MRI also enables monitoring of the progression of such lesions, supporting timely medical intervention.

  • MRI imaging clearly illustrates the spatial relationship between the epileptogenic lesion and surrounding normal brain structures, providing critical information for assessing the feasibility, risks, and preoperative planning of surgical interventions (such as temporal lobe epilepsy surgery).

  • Hence, identifying specific structural abnormalities and changes within the brain assists in determining the root cause of epilepsy, allowing for the development of personalised treatment strategies — such as medication adjustments, surgical outcome predictions, and postoperative recovery planning.
     

• Computed Tomography (CT):

  • In emergency situations, such as haemorrhagic stroke or head injury, or when MRI is contraindicated, a CT scan can serve as a supplementary imaging tool to MRI.
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• Electroencephalography (EEG): Neurological Diagnostic Test:

  • Electroencephalography (EEG) is a diagnostic tool that records the brain’s electrical activity to detect and identify abnormal epileptiform discharges. It is one of the most important investigations for diagnosing epilepsy.

  • EEG recording of cerebral electrical activity

  • During an EEG examination, electrodes are placed on the patient’s scalp to monitor normal brainwave patterns and detect abnormal epileptic electrical activity.

  • However, if seizures are infrequent or unpredictable, an initial EEG may fail to capture abnormal epileptiform patterns.

  • In such cases, prolonged monitoring — such as a 24-hour or longer video EEG — may be required to increase the likelihood of capturing epileptic discharges.

  • A Sleep EEG may further enhance detection sensitivity, as certain seizure patterns or abnormal discharges manifest more readily during sleep.

  • It is important to note that even if all EEG results are negative, epilepsy cannot be definitively excluded, as the abnormal epileptic activity may simply not have been captured during the recording period.
     

• Normal Resting EEG:

  • The top image shows a normal resting EEG with regular and symmetrical waveforms. The background brain activity appears smooth and consistent, without abnormal spikes or sharp waves.
     

• Focal Seizure EEG:

  • The middle image demonstrates focal epileptiform activity confined to a specific area of one cerebral hemisphere. This presents as sharp waves, spikes, or spike-and-slow-wave complexes, which typically appear intermittently and correlate with localised clinical symptoms.
     

• Generalised Seizure EEG:

  • The bottom image depicts generalised epileptic activity affecting both cerebral hemispheres synchronously.
    Common patterns include generalised spike-and-wave complexes (such as the characteristic 3 Hz pattern seen in absence seizures) or rapid spike activity.
    These synchronised and abnormal brainwaves exhibit high amplitude, rhythmicity, and symmetry, widely distributed across the cortex, reflecting diffuse cortical epileptiform activity leading to generalised seizures.

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• A negative EEG does not necessarily exclude epilepsy:

  • Some patients may have normal or inconclusive EEG findings, particularly if seizure frequency is low or occurs under specific circumstances.

  • Therefore, the diagnosis of epilepsy must integrate clinical history, seizure descriptions, EEG findings, and other diagnostic investigations.

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• Other Investigations:

  • Blood Tests: To exclude electrolyte imbalances or other metabolic causes.

  • Lumbar Puncture: Indicated when central nervous system infections such as meningitis are suspected.