The following is a point-of-care summary of the October, 2019 Emergency Medicine Practice journal issue titled Nonconvulsive Status Epilepticus: Overlooked and UndertreatedClick here for access to additional featured content from this issue, as well as subscription information. Subscribe or purchase a single issue and complete the activity to earn4 AMA PRA Category 1 Credits™. This summary is provided with the permission of our content partner EB Medicine.


Summary

Nonconvulsive status epilepticus is a persistent alteration in behavior or consciousness due to seizure, in the absence of convulsive activity. The absence of convulsions makes it a difficult condition to diagnose. The first step is including it in the differential for altered mental status or new onset psychiatric symptoms. Additionally, access to electroencephalography (EEG) is important and typically a limiting factor for most emergency departments. Evidence on this entity is limited and prognosis is heavily tied to the underlying cause. Treatment is largely extrapolated from epileptic seizure therapy.


Definitions: 

  • Nonconvulsive seizure: altered mental status without motor activity
  • Partial seizure: abnormal neuronal firing limited to one hemisphere
    • Simple: no change in mental status
    • Complex: altered mental status
  • Generalized seizure: abnormal neuronal firing diffusely across both hemispheres
  • Status epilepticus:
    • Classically defined as continuous seizure >30 minutes, or multiple seizures within 30 min without return to baseline. 
    • Clinically, individual seizures that last >5 min are prone to persist or recur before full recovery and likely represent status epilepticus. 1

Prevalence: 

Little evidence exists due to varied presentations and delay in diagnosis. Two small prospective studies found:

  • (1994) 34% of ED patients with altered consciousness had nonconvulsive status epilepticus.3
  • (2013) 5% of ED patients with altered mental status had nonconvulsive status epilepticus.4
  • Altered mental status is the presenting complaint in 5%, with 30% found to have some form of neurologic condition.5
  • Prognosis varies greatly depending on sub-type and underlying condition. (see table 2)
    • Nonconvulsive status epilepticus in patients with hypoxic-ischemic encephalopathy after cardiac arrest has an almost 100% mortality. 
    • Absence status epilepticus morbidity and mortality is close to 0.
  • 50% of patients with nonconvulsive status epilepticus have a history of epilepsy.6

Etiology:

Table 3. Common Etiologies of Nonconvulsive Status Epilepticus

History:

Table 5. Clinical Findings and Risk Factors in Nonconvulsive Status Epilepticus

Diagnostics: 

  • Measure Glucose and Sodium
  • Per ACEP clinical policy on AMS, a non-contrast CT head of the head is recommended. 
  • LP if infection is suspected and there are no contraindications.
    • Pleocytosis can be seen in 20-30% of convulsive seizures. 
  • EEG- electroencephalography
    • Emergent bedside EED
    • Consider continuous EEG if available.

Treatment:

Management is extrapolated from treatment of seizures as there are no guidelines or studies of the treatment of NCSE.

  • IV placement
  • Treat hypoglycemia or hyponatremia
  • Administer thiamine 100mg IV if history of alcoholism or malnourished.
  • Treat underlying cause.
  • Empiric antibiotics if infection is suspected, do not delay for LP or CT.
Table 7. Pharmacotherapy for Nonconvulsive Status Epilepticus

References:

  1. Brophy GM, Bell R, Claassen J, et al. Guidelines for the evaluation and management of status epilepticus. Neurocrit Care. 2012;17(1):3-23.
  2. Trinka E, Cock H, Hesdorffer D, et al. A definition and classification of status epilepticus–report of the ILAE Task Force on Classification of Status Epilepticus. Epilepsia. 2015;56(10):1515-1523.
  3. Privitera M, Hoffman M, Moore JL, et al. EEG detection of nontonic-clonic status epilepticus in patients with altered consciousness. Epilepsy Res. 1994;18(2):155-166.
  4. Zehtabchi S, Abdel Baki SG, Grant AC. Electroencephalographic findings in consecutive emergency department patients with altered mental status: a preliminary report. Eur J Emerg Med. 2013;20(2):126-129.
  5. Kanich W, Brady WJ, Huff JS, et al. Altered mental status: evaluation and etiology in the ED. Am J Emerg Med. 2002;20(7):613-617.
  6. Barry E, Hauser WA. Status epilepticus: the interaction of epilepsy and acute brain disease. Neurology. 1993;43(8):1473-1478.

This summary is provided with the permission of our content partner EB Medicine; http://www.ebmedicine.net

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