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EEG monitoring during carotid endarterectomy
J P Fletcher1, J G Morris, J M Little
1Department of Surgery, Westmead Hospital, NSW, Australia.
Insights
Electroencephalography (EEG) monitoring during carotid endarterectomy helps identify patients needing shunts. Shunting is recommended if EEG changes occur, regardless of internal carotid back pressure (ICBP), for improved patient outcomes.
Area of Science:
- Neurosurgery
- Neurology
- Vascular Surgery
Background:
- Carotid endarterectomy is a surgical procedure to remove plaque from carotid arteries.
- Intraoperative monitoring is crucial to prevent neurological complications during the surgery.
- Electroencephalography (EEG) and internal carotid back pressure (ICBP) are used to assess cerebral perfusion.
Purpose of the Study:
- To evaluate the utility of intraoperative electroencephalographic (EEG) monitoring in guiding shunting decisions during carotid endarterectomy.
- To compare neurological deficit rates between patients with and without EEG monitoring.
- To determine the optimal criteria for shunting based on EEG changes and ICBP.
Main Methods:
- A randomized controlled trial involving 131 patients undergoing 142 carotid endarterectomies.
- Patients were assigned to either EEG monitoring or no monitoring groups.
- Shunting criteria included ICBP < 50 mmHg and/or EEG changes (ipsilateral).
Main Results:
- Overall postoperative death rate was 0.7% and neurological deficits occurred in 3.5% of patients.
- Significantly fewer neurological deficits were observed in patients with no EEG changes (P = 0.02).
- A significant increase in neurological deficit occurred when adequate ICBP (≥50 mmHg) was present but EEG changes were observed (P = 0.005).
Conclusions:
- Intraoperative EEG monitoring is a valuable tool for identifying patients who would benefit from shunting during carotid endarterectomy.
- Shunting is recommended in the presence of EEG changes, irrespective of ICBP.
- Proceeding without a shunt appears safe when ICBP is low but no EEG changes are detected.
Abstract:
One hundred and thirty-one patients undergoing 142 carotid endarterectomy procedures were randomized to have their operation performed either with or without intra-operative electroencephalographic (EEG) monitoring. Patients with EEG monitoring were shunted if both the internal carotid back pressure (ICBP) was less than 50 mmHg and ipsilateral change was evident on the EEG after clamping. Patients without EEG monitoring were shunted if ICBP was less than 50 mmHg. There one postoperative death (0.7%) with neurological deficits occurring in five patients (3.5%). There were significantly fewer neurological deficits (P = 0.02) in patients with no EEG change (one of 59) compared with those with EEG change (two of 13). There was a highly significant increase (P = 0.005) in incidence of neurological deficit (two of five patients) when ICBP was considered 'adequate' at 50 mmHg or greater but EEG change occurred. No neurological deficit occurred in 14 patients who were not shunted with ICBP less than 50 mmHg but with no EEG change. There was no difference in the incidence of neurological deficit in patients with low and high ICBP when both 50 and 55 mmHg were used as the cut-off points. It is concluded that EEG monitoring is useful in identifying patients requiring shunting during carotid endarterectomy. Use of a shunt is recommended if there is EEG change regardless of ICBP; conversely, if ICBP is low but there is no EEG change it would appear safe to proceed without shunting.