Pooled analysis of patients with thunderclap headache evaluated by CT and LP: is angiography necessary in patients with negative evaluations?

Assessment of acute headache in adults - what the general physician needs to know

Headache is common. Up to 5% of attendances to emergency departments and acute medical units are due to headache. Headache is classified as either primary (eg migraine, cluster headache) or secondary to another cause (eg meningitis, subarachnoid haemorrhage). Even in the acute setting the majority of cases are due to primary causes. The role of the attending physician is to take a comprehensive history to diagnose and treat benign headache syndromes while ruling out sinister aetiologies. This brief article summarises the approach to assessment of headache presenting in acute and emergency care.

Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a neurological emergency with high risk of neurological decline and death. Although the presentation of a thunderclap headache or the worst headache of a patient's life easily triggers the evaluation for SAH, subtle presentations are still missed. The gold standard for diagnostic evaluation of SAH remains noncontrast head computed tomography (CT) followed by lumbar puncture if the CT is negative for SAH. Management of patients with SAH follows standard resuscitation of critically ill patients with the emphasis on reducing risks of rebleeding and avoiding secondary brain injuries.

Can the combination of a negative computed tomography result and a negative lumbar puncture safely exclude the diagnosis of subarachnoid hemorrhage in patients with thunderclap headache?

CLINICAL QUESTION

How many patients who had a negative computed tomography and lumbar puncture result on initial evaluation were diagnosed with subarachnoid hemorrhage in the subsequent 6 months to 3 years?

ARTICLE CHOSEN

Perry J, Spacek A, Forbes M, et al. Is the combination of negative computed tomography result and negative lumbar puncture result sufficient to rule out subarachnoid hemorrhage? Ann Emerg Med 2008;51:707-13.

OBJECTIVE

To determine the sensitivity of both a negative computed tomography and a negative lumbar puncture in ruling out subarachnoid hemorrhage.

Clinical Guidelines for the Emergency Department Evaluation of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is frequently caused by the rupture of an intracranial aneurysmal vessel or arteriovenous malformation, leading to a cascade of events that can result in severe disability or death. When evaluating for this diagnosis, emergency physicians have classically performed a noncontrast computed tomography (NCCT) scan, followed by a lumbar puncture (LP). Recently, however, as CT technology has advanced, many studies have questioned the necessity of the LP in the SAH diagnostic algorithm and have instead advocated for noninvasive techniques, such as NCCT alone or NCCT with CT angiogram (CTA).

OBJECTIVE

The primary goal of this literature search was to determine the appropriate emergency department (ED) management of patients with suspected SAH.

METHODS

A MEDLINE literature search from October 2008 to June 2015 was performed using the keywords computed tomography AND subarachnoid hemorrhage AND lumbar puncture, while limiting the search to human studies written in the English language. General review articles and single case reports were omitted. Each of the selected articles then underwent a structured review.

RESULTS

Ninety-one articles were identified, with 31 papers being considered appropriate for analysis. These studies then underwent a rigorous review from which recommendations were developed.

CONCLUSIONS

The literature search supports that NCCT followed by CTA is a reasonable approach in the evaluation of ED patients with possible SAH.

The value of CT angiography in patients with acute severe headache

Patients with acute severe headache may have a secondary form of headache. Standard head computer tomography (CT) and cerebrospinal fluid (CSF) examination are often performed in the absence of neurological deficits to exclude subarachnoid hemorrhage (SAH). Increasingly, patients undergo subsequent CT angiography (CTA) to exclude cerebral venous thrombosis (CVT), dissection or reversible cerebral vasoconstriction syndrome (RCVS). It is unknown whether this additional imaging increases diagnostic yield. We aimed to evaluate the yield of CTA in patients with acute severe headache with normal neurological examination and no abnormalities at standard CT and CSF analysis. We included consecutive patients presenting to the emergency room between January 2008 and May 2011 with acute severe headache and without abnormalities at neurological examination, CT and CSF research, who received a CTA in the diagnostic process in our teaching hospital. All scans were rereviewed by an experienced neuroradiologist. We included 70 patients, 71% were women and average age was 45 years. We found a vascular abnormality in 13 (19%) of our patients. Four had either a prior aneurysm or CVT. Eight patients had an unruptured intracranial aneurysm (UIA) on CTA (11%), two had CVT (3%), two had RCVS (3%) and one had cerebral ischemia (1%). We found a high percentage of vascular abnormalities. A third of these patients had a prior episode of either an aneurysm or CVT. In patients with a history of UIA or CVT performing CTA despite normal CT and LP therefore seems warranted. A prospective study to delineate indications for CTA is needed.

Benefit of cerebrospinal fluid spectrophotometry in the assessment of CT scan negative suspected subarachnoid haemorrhage: a diagnostic accuracy study

This study aimed to determine if performing cerebrospinal fluid spectrophotometry in addition to visual inspection detects more ruptured cerebral aneurysms than performing cerebrospinal fluid visual inspection alone in patients with a normal head CT scan but suspected of suffering an aneurysmal subarachnoid haemorrhage (SAH). We performed a single-centre retrospective study of patients presenting to the emergency department of a tertiary hospital who underwent both head CT scan and lumbar puncture to exclude SAH. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of an approach utilising both spectrophotometry and visual inspection (combined approach) was compared to visual inspection alone. A total of 409 patients (mean age 37.8 years, 56.2% female) were recruited and six (1.5%) had a cerebral aneurysm on angiography. The sensitivity of visual inspection was 50% (95% confidence interval [CI]: 12.4-82.6%), specificity was 99% (95% CI: 97.5-99.7%), PPV was 42.9% (95% CI: 10.4-81.3%) and NPV was 99.2% (95% CI: 97.8-99.8%). The combined approach had a sensitivity of 100% (95% CI: 54.1-100%), specificity of 79.7% (95% CI: 75.4-83.5%), PPV of 6.8% (95% CI: 2.6-14.3%) and a NPV of 100% (95% CI: 98.8-100%). The sensitivity of the combined approach was not significantly different to that of visual inspection alone (p=0.25). Visual inspection had a significantly higher specificity than the combined approach (p<0.01). The combined approach detected more cases of aneurysmal SAH than visual inspection alone, however the difference in sensitivity was not statistically significant. Visual xanthochromia should prompt angiography because of a superior specificity and PPV. Due to its reduced sensitivity, caution should be applied when using only visual inspection of the supernatant.

Retrospective audit of the investigation of patients with suspected acute subarachnoid haemorrhage

INTRODUCTION

Recommended investigational care (RIC) of emergency department (ED) patients with suspected subarachnoid haemorrhage comprises lumbar puncture (LP) to detect xanthochromia if the preceding CT scan is negative.

METHODS

Retrospective audit of the investigational care of 100 consecutive ED patients presenting with possible subarachnoid haemorrhage.

RESULTS

Of the 100 patients, 91 had negative CT, and 36 (39.6%) of these patients had an LP performed to detect xanthochromia (i.e. RIC). Fifty-five of 91 (60.4%) patients did not receive RIC. Of the 55 patients who did not receive RIC, 25 (45.5%) had a documented senior clinical decision not to perform an LP; 15 (27.3%) had no documented reason; five (9.1%) refused consent; two (3.6%) had an LP but no xanthochromia requested, one patient did not have an LP because of technical issues, six patients underwent CT angiography (CTA), and one patient underwent magnetic resonance angiography (MRA), in the absence of a LP, following a negative CT. Two patients underwent CTA following a negative xanthochromia result. Patients admitted to the emergency extended care unit had 6.85 times the odds of receiving RIC (95% CI 2.20-21.4).

CONCLUSIONS

Fifty-five (55) of 91 (60%) ED patients did not receive RIC. Fifteen of the 55 did not have any documented justification for not performing an LP with xanthochromia testing. Admission to an emergency extended care unit was a predictor of receiving RIC. Inappropriate use of CTA and MRA was identified. These findings have important implications for patient safety. Multifaceted strategies are required to close this evidence-practice gap.

Abrupt-onset severe headaches

Thunderclap headache, a severe headache which is maximal in intensity at onset, is associated with numerous underlying disorders, including subarachnoid hemorrhage, unruptured intracranial aneurysm, cervical artery dissection, cerebral venous sinus thrombosis, stroke, intracranial hemorrhage, reversible cerebral vasoconstriction syndrome, and reversible posterior leukoencephalopathy. After exclusion of all possible causes, thunderclap headache may be considered a primary headache. This review summarizes the diagnostic considerations and clinical approach to thunderclap headache, with particular emphasis on the reversible cerebral vasoconstriction syndromes.