Triphasic waves (TWs) are a distinctive, although non-specific EEG pattern, which are quite frequently encountered and sometimes difficult to interpret. Although initially considered pathognomonic of hepatic encephalopathy, TWs have been described in association with a large number of conditions. TWs may occur in encephalopathies (metabolic or structural) or as an ictal pattern. Nonepileptic TWs with sharply contoured morphology may resemble epileptic patterns encountered in nonconvulsive status epilepticus (NCSE), thus leading to misinterpretation and overinterpretation of this pattern as ictal, if only the EEG is considered. An electroclinical response to benzodiazepines and the evaluation of consciousness impairment should be considered when interpreting TWs. Evaluating only the EEG without considering also clinical and laboratory findings is not only useless and meaningless, but may even lead to serious consequences.
Transcranial Doppler (TCD) is well known for its usefulness in diagnosing vasospasm in patients with subarachnoid hemorrhage and vasculopathy in children with sickle cell disease. However there are some lesser known TCD studies. Bubble studies detect right to left shunts. Head rotation studies evaluate for extrinsic compression of the vertebral arteries. CO2 challenge and breath holding studies evaluate vasomotor reserve. Reactive hyperemia studies help diagnose subclavian steal. Emboli monitoring detects any particulates that might be present in the cerebral blood flow.
Episodic loss of consciousness can be caused by epileptic seizures, but other etiologies must be considered. We report a patient with dramatic loss of consciousness during tilt-table testing and discuss the typical EEG findings and clinical manifestations during convulsive syncope.
Carotid artery stenosis is a major risk factor leading to cerebral infarct, transient ischemic attack (TIA), and ischemic stroke in the United States. While carotid endarterectomy (CEA) surgery has been established as an effective treatment option for severe carotid artery stenosis, many risks remain inherent in performing this procedure. Surgeons will often utilize various intraoperative monitoring techniques in an effort to reduce surgical complications and morbidity. The usefulness of continuous EEG and somatosensory evoked potential (SSEP) monitoring during CEA surgery has been examined by many groups over the last couple decades. The following case review clearly proves that such monitoring is an effective tool in the detection of cerebral ischemic changes and is therefore feasible in CEA surgery.
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