Question 4

College answer

Syllabus topic/section: 2.1.8 Neurological Intensive Care / Seizure disorders including status epilepticus: L1

Discussion: NCSE is a distinct clinical entity from status epilepticus. Candidates who acknowledged those nuances and addressed this in their answer were able to demonstrate the standard required. Candidates can ensure they cover breadth by considering the types of information used clinically when securing a diagnosis as history, examination and investigations all contribute to diagnostic reasoning. Answers with structure, (for example, in part a) using headings which could include practical, logistical and clinical challenges among others) were rewarded.
Better answers to part C addressed control of seizures, prevention of secondary injury, finding and treating precipitants and involved a strategy for de-escalation. Outline is a glossary term that is defined as ‘provide a summary of the important points’ which is more than a simple list. For parts A and B, the question asked for an outline and accordingly higher marks were awarded for structured, details answers. As an illustration, general comments about the importance of maintenance of MAP/normoxia/normoglycaemia did not gain marks unless they were contextualised as neuroprotective cares for the patient with NCSE.
It is expected that just listing anti-epileptics is not enough to demonstrate the standard of competence required at the level of a transitional fellow who will be entrusted with independent practice of the critically ill. More detail in terms of dosing considerations, an approach to drug interactions and ways to mitigate unintended consequences is needed.

Discussion

Challenges:

• Distinguishable from convulsive SE by not involving motor cortex neurons, but also may be distinct in other ways, eg. potentially not a distinct disease process but rather a marker of severity of CNS dysfunction 
• No clinical findings
• No agreement on the diagnostic criteria by which to identify this condition.
• What criteria we have are based on EEG, but EEG may not capture the epileptiform discharges if it is only performed during an interictal period
• Even when EEG is available, EEG findings are frequently non-specific which should also be interpreted as features of encephalopathy

Risk factors:

• Known epileptic with an acute infection
• Recent convulsive seizures
• Remote risk factors for seizures:
  • previous stroke
  • tumour
  • neurosurgery
  • dementia
  • multiple sclerosis
  • encephalitis or meningitis

Principles of management

• Treatment of the underlying precipitant is essential
• Controversy exists as to whether one should offer any treatment at all to the NSCE itself
• It is unclear whether it causes neurological damage (animal data, mostly)
• Guidelines are mostly extrapolated from convulsive SE, which means they may be too aggressive
• Management should be reserved for patients in whom the added benefit of management has clear advantages (eg. decreased CNS oxyegnc consumption in TBI)
• Prognosis is mostly determined by the prognosis of the underlying disease; management of patients with lower severity of underlying disease should therefore be more conservative
• For pharmacotherapy, benzodiazepines are first line
• Valproate, levitiracteam and lacosamide are second line
• Seek to reduce threshold-lowering stimuli (eg. hyponatremia)
• Antiepileptic therapy must be guided by serial or continuous EEG, as clinical features are subtle and difficult to track