Non-Convulsive Status Epilepticus

Most chief complaints generate a clear Differential Diagnosis (Ddx) list in your mind. There are the well-known, “big ticket” issues that need to be considered (Abdominal Pain -> Appendicitis; Chest Pain -> Pericarditis; Headache -> Meningitis) as well as the more common causes (Abdominal Pain -> CRAP; Chest Pain -> Asthma; Headache -> Benign Headaches). The challenge with children, as we have stated numerous times, is that the significant problems can masquerade as benign ones. Additionally, their non-specific presentations overlap greatly, requiring us to be ever vigilant. One presentation that requires a very broad Ddx list is Altered Mental Status. Let us take a minute to highlight one item on that Ddx list that may be overlooked – Non-Convulsive Status Epilepticus in Children:

Non-Convulsive Status Epilepticus

  • My simple definition: Non-Convulsive Status Epilepticus (SE) = an electrical storm in the brain, but there is no shaking on the outside.
  • The actual definition is more complicated … [Jafarpour, 2015; Wilson, 2015; Abend, 2009]
    • Electromechanical uncoupling, when electrical seizure activity persists despite resolution of the clinical manifestations.” [Wilson, 2015] (I like that one)
    • “Nearly continuous electrographic seizures without convulsive activity, manifesting as: [Abend, 2009]
      • Altered Mental Status or
      • Coma
  • Various definitions also include: [Jafarpour, 2015; Abend, 2009]
    • 3 Criteria:
      • Cognitive deficits
      • Evidence of subconical seizures on EEG
      • Improvement after suppression/remission of seizures
    • Duration?? Kinda depends…
      • Definition varies based on year of study…
      • Prior to 2012, Status Epilepticus required at least 30 min of seizure / not returning to baseline.
      • In 2012, Status Epilepticus definition changed to include seizure activity lasting > 5 min (although, adverse outcomes still associated with 30 min threshold.
      • In reality, we are not going to diagnose Non-convulsive SE after only 5 min of altered mental status… but, considering it early will hopefully help get the EEG ordered sooner!
  • It is NOT Rare! [Abend, 2009]
    • It is common in ALL inpatient settings, not just the PICU. [Greiner, 2012]
      • Estimates vary (based on the definition used).
      • Incidence as high as 46% of critically ill children.
      • In children with clinical suspicion for non-convulsive SE, 14% found to have it. [Greiner, 2012]
    • It is often under-diagnosed / under-recognized [Greiner, 2012; Tay, 2006]
      • It is difficult to diagnose as it may be confused with behavioral change.
      • 23 – 34% of cases who had EEG monitoring for altered mental status in the ED had non-convulsive SE! [Abend, 2009]
  • It does have consequences! [Jafarpour, 2015; Abend, 2009]
    • Non-convulsive SE has been associated with:
      • Higher mortality
      • Longer PICU stays
      • Greater short term disability
      • Greater long term disability
    • Morbidity and Mortality often predicated upon underlying condition… but non-convulsive SE can occur in absence of acute etiology. [Jafarpour, 2015; Greiner, 2012]
  • Continuous EEG is required to make the diagnosis! [Wilson, 2015]
    • The lack of external seizure activity makes this challenging to detect.
      • There may be subtle “twitching” or “abnormal eye movement.”
      • May also present as: [Yamaguchi, 2019]
        • Agitation
        • Lethargy
        • Delirium
        • Abnormal Movements
        • Prolonged Altered Consciousness
      • Ultimately, the diagnosis is dependent upon the EEG findings.
    • Prompt recognition is important to be able to improve outcomes. [Yamaguchi, 2019; Greiner, 2012; Tay, 2006]
      • Initiation of EEG is often delayed…
        • Hard to recognize need.
        • Hard to coordinate STAT EEG.
        • Reduced-lead (4 channel) EEG or EEG “cap” has been successful at detecting seizure activity within 1 hour! [Yamaguchi, 2019; Jafarpour, 2015; Greiner, 2012; Abend, 2009]
      • Early EEG (even in the ED) can help pick up on the diagnosis early and affect therapy.
        • ~50% of non-convulsive SE can be seen in first hour.
        • 80-87% detected within 24 hours of continuous EEG monitoring.

Non-Convulsive Status Epilepticus: When To Consider

  • High Risk for Non-Convulsive SE [Wilson, 2015; Jafarpour, 2015; Greiner, 2012]
    • Acute Encephalopathy
    • Status Epilepticus or Refractory Status Epilepticus [Tay, 2006]
      • Just because you successfully resolved the external shaking, doesn’t mean the brain is still not in a chaotic electrical storm.
      • Certainly, if you intubated the patient, then the paralytic will create “non-convulsive SE.”
  • Other considerations for Non-Convulsive SE [Wilson, 2015; Greiner, 2012]
    • Underlying Epilepsy Diagnosis
    • Younger Age (< 24 months of age)
    • Underlying Congenital Heart Disease
  • Use of a Reduced-Lead EEG (only 4 electrodes) has been shown to help expedite detection of non-convulsive SE while patient is still in the ED. [Yamaguchi, 2019]

Moral of the Morsel

  • Altered Mental Status does not just equal “CT / LP.” Consider the broad Ddx. TIPS AEIOU!
  • Acting oddly… it may be the chaotic brain-storm! Add non-convulsive status epilepticus to the Ddx of altered mental status.
  • EEG early can help! It may not be easy to get… all the more reason to start that process early!

References

Yamaguchi H1, Nagase H2, Nishiyama M2, Tokumoto S3, Ishida Y3, Tomioka K2, Tanaka T3, Fujita K4, Toyoshima D5, Nishimura N2, Kurosawa H6, Nozu K2, Maruyama A5, Tanaka R4, Iijima K2. Nonconvulsive Seizure Detection by Reduced-Lead Electroencephalography in Children with Altered Mental Status in the Emergency Department. J Pediatr. 2019 Apr;207:213-219. PMID: 30528574. [PubMed] [Read by QxMD]
Chen J1, Xie L1, Hu Y1, Lan X1, Jiang L2. Nonconvulsive status epilepticus after cessation of convulsive status epilepticus in pediatric intensive care unit patients. Epilepsy Behav. 2018 May;82:68-73. PMID: 29587188. [PubMed] [Read by QxMD]
Fujita K1, Nagase H1, Nakagawa T2, Saji Y3, Maruyama A1, Uetani Y2. Non-convulsive seizures in children with infection-related altered mental status. Pediatr Int. 2015 Aug;57(4):659-64. PMID: 25523443. [PubMed] [Read by QxMD]
Wilson CA1. Continuous electroencephalogram detection of non-convulsive seizures in the pediatric intensive care unit: review of the utility and impact on management and outcomes. Transl Pediatr. 2015 Oct;4(4):283-9. PMID: 26835390. [PubMed] [Read by QxMD]
Jafarpour S1, Loddenkemper T2. Outcomes in pediatric patients with nonconvulsive status epilepticus. Epilepsy Behav. 2015 Aug;49:98-103. PMID: 26216724. [PubMed] [Read by QxMD]
Galimi R1. Nonconvulsive status epilepticus in pediatric populations: diagnosis and management. Minerva Pediatr. 2012 Jun;64(3):347-55. PMID: 22555329. [PubMed] [Read by QxMD]
Greiner HM1, Holland K, Leach JL, Horn PS, Hershey AD, Rose DF. Nonconvulsive status epilepticus: the encephalopathic pediatric patient. Pediatrics. 2012 Mar;129(3):e748-55. PMID: 22331332. [PubMed] [Read by QxMD]
Abend NS1, Marsh E. Convulsive and nonconvulsive status epilepticus in children. Curr Treat Options Neurol. 2009 Jul;11(4):262-72. PMID: 19523352. [PubMed] [Read by QxMD]
Tay SK1, Hirsch LJ, Leary L, Jette N, Wittman J, Akman CI. Nonconvulsive status epilepticus in children: clinical and EEG characteristics. Epilepsia. 2006 Sep;47(9):1504-9. PMID: 16981867. [PubMed] [Read by QxMD]

Sean M. Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renowned educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

You may also like...

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.