Original Contribution
Systematic combined noncontrast CT–CT angiography in the management of unexplained nontraumatic coma

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Abstract

Background

Nontraumatic impaired consciousness is a common issue in emergency departments with a serious but widely variable prognosis.

Study objectives

The aim of this prospective study was to evaluate the ability of systematic combined noncontrast computed tomography (NCCT)/computed tomography angiography (CTA) imaging, firstly to provide a neurologic prognosis and secondly to ensure early detection of basilar artery occlusion (BAO), in unexplained nontraumatic impaired consciousness management.

Methods

Combined NCCT/CTA imaging was performed on 65 patients with impaired consciousness and no history of trauma prospectively over 14 months in a single center. Images were assessed based on visual and quantitative criteria. Clinical outcome was assessed using the modified Rankin Scale at 3 months. Statistical analysis aimed to identify the prognostic value of combined NCCT/CTA imaging and its ability for early BAO detection.

Results

This study shows that combined NCCT/CTA imaging was a significant predictor of poor neurological outcome, with a positive predictive value of 94.6%. The combination was also crucial for early detection of BAO, given that 42.8% of cases were misdiagnosed with NCCT alone. Basilar artery occlusion represented 10.8% of all unexplained nontraumatic impaired consciousness.

Conclusions

Systematic combined NCCT/CTA imaging is an efficient tool for predicting poor neurologic prognosis in cases of unexplained nontraumatic impaired consciousness and is also essential for detecting BAO.

Introduction

Unexplained nontraumatic impaired consciousness is a common issue in emergency departments (EDs) with widely variable outcomes ranging from death and vegetative state, to fully conscious recovery with or without disability. The frequency of the different issues varies in the literature and largely depends on etiology [1], [2], [3], [4], [5], [6], [7], [8], but prognosis in patients presenting with nontraumatic impaired consciousness is serious, with death rates varying from 26.5% at discharge to 61.0% at 1 year. It is, therefore, challenging to identify prognostic factors for clinical outcomes, and computed tomographic (CT) imaging may offer a readily available and efficient tool for this purpose. Noncontrast CT (NCCT) performed early on is known to be crucial for the emergency management of impaired consciousness patients, mainly to exclude a diagnosis of hemorrhage or intracranial malignancy [9], which may require immediate neurosurgical treatment. However, NCCT has several drawbacks including a lack of sensitivity (Se) in detecting ischemic stroke in the posterior circulation [3], [10] and, particularly, in the first few hours after symptom onset. To improve imaging diagnosis efficacy, helical multidetector CT angiography (CTA) recently emerged as an efficient tool for evaluating the intracranial arteries and identifying vessel occlusion or stenosis [11]. Acknowledged as a highly important examination for confirming or ruling out aneurysm in the event of hemorrhagic stroke [12], CTA has also shown its feasibility and value in acute stroke patients [13].

Basilar artery occlusion (BAO) represents only approximately 1% of all cerebral ischemic events [14] but is often revealed by sudden impaired consciousness (30 à 40% of patients with BAO) [15] following the onset of motor and bulbar symptoms and is associated with a very poor prognosis. Yet, BAO may benefit from specific treatment, such as intravenous thrombolysis or more recently endovascular treatment. These treatments have been seen to improve patient outcomes with an average 50% of good neurologic outcomes at 3 months, whereas 90% of patients who did not receive therapy died [16], [17]. The systematic use of CTA immediately after NCCT should help to identify a treatable etiology of impaired consciousness, mainly in the early detection of BAO, and may then be used to evaluate and improve patient prognosis [16], [18].

The aim of this prospective study was to demonstrate the contribution of systematic combined NCCT/CTA in unexplained nontraumatic impaired consciousness management. Our primary objective was to evaluate the ability of combined NCCT/CTA imaging to provide a neurologic prognosis. Our secondary objective was to evaluate ability for early BAO detection.

Section snippets

Study design

This prospective, single-center study was conducted between May 1, 2010, and July 31, 2011, on patients admitted to our university hospital ED for unexplained nontraumatic impaired consciousness. Systematic combined NCCT/CTA imaging was performed for all the consecutive patients satisfying the inclusion and exclusion criteria at time of entry in the radiology suite. The study was approved by the local ethics committee.

Patients

The inclusion criteria were a Glasgow Coma Scale (GCS) score of 10 or less [3]

Etiologies of nontraumatic impaired consciousness

The etiologies of impaired consciousness finally selected by the clinicians are shown in Table 1.

The overall mortality rate at 3 months was 52.3%, varying from 0.0% (0/3, 0/1, and 0/2, respectively) for isolated epilepsy, meningitis, and psychiatric disorder; 15.0% (3/20) for poisoning, metabolic or immune disorder, or respiratory failure; 50.0% (1/2 and 1/2, respectively) for intracranial malignancy and circulatory failure post cardiac arrest; and 82.9% (29/35) for stroke.

Combined NCCT/CTA imaging for neurologic outcome prognosis

Noncontrast CT/CTA

Discussion

This prospective study showed that systematic use of combined NCCT/CTA imaging was an efficient indicator of neurologic outcome prognosis in the management of unexplained nontraumatic impaired consciousness. Moreover, this imaging modality combination was crucial for diagnosing BAO due to possible misdiagnosis with NCCT alone.

Conclusion

Systematic combined NCCT/CTA imaging is an efficient tool for predicting poor neurologic prognosis in the management of unexplained nontraumatic impaired consciousness. As the first step of an appropriate management protocol, combined NCCT/CTA imaging is essential for detecting BAO, a condition for which the main prognostic criterion is the interval before treatment.

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    Conflict of interest: The authors declare that they have no conflict of interest.

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