spike-wave stupor in a patient with metabolic encephalopathy
TRANSCRIPT
Letter to the Editor
Spike-wave stupor in a patient with metabolic encephalopathy
Dear Editor,
The case report on spike wave stupor in a patientwith metabolic disorder1 contains insufficient clinical evi-dence to fully assess the significance of the authors’claims. It is well recognised that triphasic waves inhepatic encephalopathy can be abolished by benzodiaze-pines.2 Of critical importance in determining if this isindeed an epileptic phenomenon rather than a metabolicencephalopathy is whether the patient regainedconsciousness following the administration of IVdiazepam.
References
1. Momoo T, Johkura K, Kuroiwa Y. Spike-wave stupor in a patient withmetabolic encephalopathy. J Clin Neurosci 2006;13:300–3.
2. Fountain NB, Waldman WA. Effects of benzodiazepines on triphasicwaves. Implications for nonconvulsive status epilepticus. J Clin
Neurophysiol 2001;18:345–52.
Bruce DayDepartment of Neurology, Alfred Hospital,
Commercial Road, Prahran, Melbourne,
3181 Victoria, Australia
E-mail address: [email protected]
doi:10.1016/j.jocn.2006.03.015
Reply
Spike-wave stupor and triphasic waves
Dear sir,
We appreciate the comments by Dr. Day on our casereport. We are aware that, in hepatic encephalopathy, sharpwaves in EEG can be abolished, and background activity isslowed by benzodiazepines.1 In our patient, sharp waves dis-appeared after benzodiazepine administration. However,the emerged background activity was near-normal.2 Besidesthis, in our patient, sharp waves were always higher in ampli-tude, and the sharp and slow wave complexes lasted regu-larly and continuously. These are characteristic EEGfeatures of epileptic spike-wave discharges rather than met-abolic triphasic waves.3,4 The characteristics of spike-wavedischarges itself, together with the nearly normalized back-ground activity by benzodiazepin,5 suggest that our patient’sdecreased consciousness was of epileptic etiology.
Our patient regained consciousness several days afterbenzodiazepine administration. Her plasma ammonia levelwas still elevated after she regained consciousness.Although the state of consciousness is not usually associ-ated with the level of ammonia,6 this clinical course mayalso support that this is an epileptic phenomenon ratherthan a metabolic encephalopathy.
Spike-wave stupor in our patient may be due to secondaryepileptogenesis caused by metabolic disorder.2 Moreover,metabolic triphasic waves may possibly be generated by dis-orders of the thalamocortical pathway which are thought togenerate epileptic spike-wave discharges.7 Thus, in our
patient, it may be difficult to draw a sharp line between epi-leptic spike-wave discharges and metabolic triphasic wavesin a sense.
References
1. Fountain NB, Waldman WA. Effects of benzodiazepines on triphasicwaves: implications for nonconvulsive status epilepticus. J Clin
Neurophysiol 2001;18:345–52.2. Momoo T, Johkura K, Kuroiwa Y. Spike-wave stupor in a patient with
metabolic disorder. J Clin Neuorsci 2006;13:301–3.3. Mrtı́nez-Rodrı́guez JE, Barriga FJ, Santamaria J, Iranzo A, Pareja JA,
Revilla M, et al. Nonconvulsive status epilepticus associated withcephalosporins in patients with renal failure. Am J Med 2001;111:115–9.
4. Niedermeyer E, Khalifeh R. Petit mal status (‘‘spike-wave stupor’’).Epilepsia 1965;6:250–62.
5. Sheridan PH, Sato S. Triphasic waves of metabolic encephalopathyversus spike-wave stupor. J Neurol Neurosurg Psychiatry
1986;49:108–9.6. Poser CM. Electroencephalographic changes and hyperammonemia.
Electroencephalogr Clin Neurophysiol 1958;10:51–62.7. Nowack WJ, King JA. Triphasic waves and spike wave stupor. Clin
Electroencephalogr 1992;23:100–4.
Ken JohkuraDepartment of Neurology,
Hiratsuka Kyosai Hospital,
9-11 Oiwake, Hiratsuka 254-8502,
Kanagawa, JapanTel.: +81 463 32 1950; fax: +81 463 31 1865
E-mail address: [email protected]
doi:10.1016/j.jocn.2006.05.007
Letter to the Editor / Journal of Clinical Neuroscience 14 (2007) 185–187 187