Can catatonia be detected on an electroencephalogram (EEG)?

EEG Findings in Catatonia

Electroencephalogram (EEG) can show abnormalities in catatonia, but there are no specific diagnostic EEG patterns that definitively identify catatonia. Instead, EEG serves as an important diagnostic tool to evaluate potential underlying causes of catatonia, particularly to rule out non-convulsive status epilepticus.

EEG Abnormalities in Catatonia

Common EEG Findings

• Clinical EEG abnormalities are reported in approximately 65% of patients with catatonia 1
• Most common findings include:
  • Generalized background slowing 2, 1
  • Diffuse abnormal electrical activity 3
  • Focal abnormalities, particularly in temporal and frontal areas 3

Special Considerations

Epilepsy-Related Catatonia

EEG is particularly valuable in identifying seizure activity that may underlie catatonia. There are three recognized temporal relationships between catatonia and seizures 2:

1. Ictal catatonia: Catatonia as a presentation of non-convulsive status epilepticus

   • EEG may show continuous bilateral pseudoperiodic sharp waves, spike discharges, or periodic lateralizing epileptiform discharges 4
   • Responds dramatically to anticonvulsant treatment

2. Postictal catatonia: Catatonia following a seizure

   • EEG may show postictal slowing

3. Interictal catatonia: Catatonia and seizures occurring without clear temporal relationship

Catatonia Due to Medical Conditions

• EEG abnormalities are more common in patients with:
  • Age greater than 40 years
  • Neuroleptic malignant syndrome
  • General medical conditions associated with catatonia 1

Clinical Utility of EEG in Catatonia

Diagnostic Value

• EEG is recommended as part of the standard workup for patients presenting with catatonia 5
• Helps differentiate between psychiatric and neurological causes
• Critical for identifying non-convulsive status epilepticus, which may present as catatonia 4

Treatment Implications

• Identification of epileptiform activity on EEG in catatonic patients may indicate need for anticonvulsant treatment rather than standard catatonia treatments 3, 4
• Paradoxically, electroconvulsive therapy (ECT) is an effective treatment for many forms of catatonia, even without epileptiform EEG findings 2, 5

Limitations of EEG in Catatonia Diagnosis

• No pathognomonic EEG pattern exists for catatonia 1
• Normal EEG does not rule out catatonia
• Some cases of epilepsy-related catatonia may require intracranial EEG recording to detect seizure activity not visible on standard EEG 2

Practical Approach to EEG in Catatonia

1. Obtain standard EEG in all patients presenting with catatonia
2. Consider prolonged EEG monitoring if:
   • History suggests possible seizure activity
   • First-line treatments for catatonia are ineffective
   • Fluctuating symptoms or altered consciousness
3. Interpret EEG findings in clinical context, particularly when considering:
   • Medication effects
   • Metabolic abnormalities
   • Underlying neurological conditions

EEG remains an important tool in the evaluation of catatonia, not as a definitive diagnostic test, but as a means to identify potential underlying causes and guide appropriate treatment decisions.