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|LETTERS TO EDITOR
|Year : 2017 | Volume
| Issue : 7 | Page : 100-101
Detection and management of intraoperative seizure with bispectral index monitoring in a paralyzed patient
Keta Thakkar1, Ramamani Mariappan1, Bijesh R Nair2
1 Department of Anaesthesia, Christian Medical College, Vellore, Tamil Nadu, India
2 Department of Neurological Sciences, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Web Publication||8-Mar-2017|
Department of Anaesthesia, Christian Medical College, Vellore, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Thakkar K, Mariappan R, Nair BR. Detection and management of intraoperative seizure with bispectral index monitoring in a paralyzed patient. Neurol India 2017;65, Suppl S1:100-1
|How to cite this URL:|
Thakkar K, Mariappan R, Nair BR. Detection and management of intraoperative seizure with bispectral index monitoring in a paralyzed patient. Neurol India [serial online] 2017 [cited 2017 Jul 25];65, Suppl S1:100-1. Available from: http://www.neurologyindia.com/text.asp?2017/65/7/100/201666
A 20-year-old year gentleman with left occipital high grade glioma underwent a left occipital craniotomy and tumor excision in prone position. He was administered phenytoin for seizure prophylaxis and received dexamethasone during the preoperative period. He was induced and intubated using standard anesthetic drugs. The patient was positioned prone on bolsters without jugular venous compression. As there was significant perilesional edema with a midline shift, anesthesia was initially maintained with air, oxygen, isoflurane (minimum alveolar concentration 0.5), and propofol (50–70 µg/kg/min). The dose of propofol was titrated to maintain the bispectral index (BIS) between 40 and 50. The patient was hyperventilated to maintain the end tidal carbon dioxide (ETCO2) at 28–33 mmHg. Mannitol (1 gm/kg) and dexamethasone were given to reduce cerebral edema. Despite of all these measures, the dura was very tense. Isoflurane was stopped and changed to total intravenous anesthesia (TIVA) at the rate of 100–125 µg/kg/min after a bolus dose. The patient was transiently hyperventilated further to decrease the ETCO2 to 25 mmHg. Although, the dura became slightly lax with TIVA and hyperventilation, the brain bulged out on dural opening. After the surgeon started to decompress the tumor, there was a sudden increase in BIS from 50 to 72 along with mild increase in blood pressure and heart rate [Figure 1]. There was increased brain swelling noted at this juncture. Propofol (70 mg) and fentanyl (50 µg) boluses were given and the propofol infusion was increased to 150 µg/kg/min. With this bolus propofol, the BIS dropped to 50–55. During this episode, the neuromuscular monitor did not show any twitches on 'Train of Four' stimulation indicating that the patient was deeply paralyzed. The patient had received a total of 5 µg/kg of fentanyl till then. After 15 minutes, there was a second episode of sudden increase in BIS despite an optimum dose of propofol. A probable diagnosis of intraoperative seizures was made and an additional dose of phenytoin (300 mg) and propofol were administered. To confirm the diagnosis of seizures, serum prolactin level was measured and was found to be 29.65 ng/ml (normal value: 5–12 ng/ml). Intraoperative arterial blood gas (ABG), electrolytes, and blood sugars were normal, which ruled out metabolic causes of seizure. After the partial resection of tumor, the brain became lax and pulsatile. The tumor was excised uneventfully with minimal blood loss. At the end of surgery, the patient was reversed and extubated awake without any new neurological deficit and his postoperative course was uneventful. A repeat prolactin level assay done 24 h later was normal (10.53 ng/ml).
|Figure 1: Hemodynamics and bispectral index value along with signal quality index and electromyogram at the time of seizure activityindicating|
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Pain, light plane of anaesthesia, increased electromyographic activity, increased impedance of BIS electrode, cautery interference, hyperthermia and hypoglycemia, and metabolic abnormalities, such as hyponatremia, can all cause rise in BIS, which were ruled out in our case. Moreover, a rise in BIS was noted during the tumor excision (considered to be painless); intraoperative seizure was the prime reason considered for the abnormal rise of BIS.,, According to the American Association of Neurology (AAN) Practice Guidelines, elevated serum prolactin, twice from the baseline value, 10–20 minutes after a suspected seizure, is considered be a useful adjunct to diagnose a generalized tonic–clonic seizure., In our case, the prolactin level was elevated to twice the baseline value, confirming our diagnosis.
From our case, we want to highlight that patients with a high grade intracranial tumor often present with malignant brain edema. Despite of initiation of all measures to reduce the brain edema and intracranial pressure, intraoperative brain bulging can still occur. In these cases, intraoperative seizure can be easily missed or misdiagnosed because of the presence of multiple confounders. Seizure worsens the brain edema and can cause further brain bulging. Hence, it is essential to diagnose and treat intraoperative seizures immediately to prevent neurological morbidity. BIS monitoring is a useful tool in patients who are at high risk of developing intraoperative seizures.
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