Optimizing blood pigment analysis in cerebrospinal fluid for the diagnosis of subarachnoid haemorrhage - a practical approach

Detection of subarachnoid haemorrhage with spectrophotometry of cerebrospinal fluid - a comparison of two methods

OBJECTIVES

Spectrophotometric absorption curve analysis of cerebrospinal fluid (CSF) for oxyhaemoglobin and bilirubin is necessary to accurately diagnose subarachnoid haemorrhage (SAH) in patients with typical symptoms but with negative findings on X-ray examinations. In this study, we evaluated the performance of two methods for interpreting absorption curves; one method from the United Kingdom National External Quality Assessment Service (UK-NEQAS) and the other from the national quality assurance programme in Sweden (Equalis).

METHODS

Consecutive absorbance curves (n=336) were interpreted with two different methods, and their performance was compared to the diagnosis as stated in the patient records.

RESULTS

The UK-NEQAS method displayed equal sensitivity to the Equalis method, but the specificity of the UK-NEQAS method was significantly higher than the Equalis method resulting in fewer false positive results. For UK-NEQAS, a positive predictive value (PPV) of 84.6% and a negative predictive value (NPV) of 99.7% were observed, whereas the Equalis method had a PPV of 27.5% and an NPV of 99.7%.

CONCLUSIONS

The semi-automated method based on the guidelines from UK-NEQAS provides an efficient and correct interpretation of absorbance curves with short turn-around times. We propose using this method for the routine interpretation of CSF spectrophotometric curves.

Analysis of blood degradation products and ferritin in the cerebrospinal fluid of dogs with acute thoracolumbar intervertebral disk extrusion, a prospective pilot study

Background

Hemorrhage in the spinal canal leads to further damage of the spinal cord influencing outcome in dogs with intervertebral disk (IVD) extrusion. The aim of the study was to evaluate blood degradation products and ferritin in the cerebrospinal fluid (CSF) of dogs with thoracolumbar IVD extrusion, and their association to clinical parameters and MRI findings.

Results

In the CSF of dogs with IVD extrusion, both net oxyhemoglobin absorption (NOA) and net bilirubin absorption (NBA) were significantly higher compared to the control groups of dogs with steroid responsive meningitis arteritis (SRMA) and idiopathic epilepsy (IE) (P < 0.001), but NOA compared to the idiopathic epilepsy group contaminated artificially with blood (IEc) was not (P = 0.890). Ferritin concentration was significantly higher in dogs with IVD extrusion compared to dogs with IE (P = 0.034), but not to dogs with SRMA (P = 0.526). There was no association between NOA, NBA or ferritin concentration and severity or duration of clinical signs. In dogs with a higher ferritin concentration the outcome was better (P = 0.018). In dogs with evidence of hemorrhage on MRI, NOA and NBA were significantly higher (P = 0.016, P = 0.009), but not ferritin (P = 0.0628).

Conclusion and clinical importance

Quantification of blood degradation products and ferritin in the CSF of dogs to assess subarachnoidal hemorrhage is feasible; however, larger case numbers are needed to evaluate the relevance of NBA and ferritin as prognostic indicators.

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.

Specificity of elevated cerebrospinal fluid bilirubin in the investigation of subarachnoid haemorrhage

BACKGROUND

The spectrophotometric examination of cerebrospinal fluid for bilirubin is an established investigation in patients with suspected subarachnoid haemorrhage. This study assesses the diagnostic specificity of an elevated cerebrospinal fluid bilirubin and how this may be influenced by the presence of oxyhaemoglobin and the concentration of cerebrospinal fluid total protein.

METHODS

One thousand cerebrospinal fluid spectroscopy reports were reviewed. Electronic patient records were examined to determine the clinical outcome in patients with an elevated cerebrospinal fluid bilirubin.

RESULTS

Forty-four out of 1000 cerebrospinal fluid scans showed an increase in cerebrospinal fluid bilirubin unrelated to elevated serum bilirubin concentrations. This was associated with subarachnoid haemorrhage in 16 (36%) cases. Subarachnoid haemorrhage was confirmed in 5/17 (29%) patients positive for cerebrospinal fluid bilirubin alone and in 11/27 (41%) patients positive for both cerebrospinal fluid bilirubin and oxyhaemoglobin. At cerebrospinal fluid total protein concentrations <1 g/L, the specificity for subarachnoid haemorrhage improved: 4/9 (44%) vs. 1/8 (13%) with an increase in cerebrospinal fluid bilirubin alone; 6/10 (60%) vs. 5/17 (29%) in patients with increases in both bilirubin and oxyhaemoglobin.

CONCLUSION

While an increase in cerebrospinal fluid bilirubin may be considered consistent with subarachnoid haemorrhage, the likelihood that a subarachnoid haemorrhage has occurred is influenced by the presence of oxyhaemoglobin and the concentration of total protein in the cerebrospinal fluid.