We read with interest the recent article by J Perry et al. The
authors correctly state that the proposed rules would need validation in
clinical practice. We would like to make three points.
1) We would like to share the results of a 2 year study we have
conducted. It indicates that application of their proposed rules would
result in missed diagnoses of SAH (subarachnoid haemorrhage).
Our study was performed across 4 hospitals (one tertiary centre with
neurosurgery and neuroradiological facilities, two teaching hospitals and
one district general hospital), covering two counties of England, between
2006-2008.
We examined the outcome of patients receiving lumbar puncture to
exclude a SAH, following a 'negative' scan. 372 sets of patient notes
were analysed. There were 6 cases (1.6%) of proven SAH (CSF bilirubin
positive, other causes excluded). In five patients the onset of headache
was instantaneous, or over minutes. In one patient the headache was of
gradual onset, with confusion and drowsiness over days (proven SAH
secondary to basilar aneurysm). One patient, admitted via the emergency
department was 21 years old. This patient would not have been identified
by the proposed rules. Interestingly, in only 50% (3 of the 6 proven
cases) was SAH the primary suspected diagnosis (although it was obviously
considered an important diagnosis to exclude given the history). Our
study highlights the importance of having a low threshold for
investigation of thunderclap headache.
2) Analysis of the National Health Service litigation agency database
from 1995-2002 identified emergency medicine as the most common speciality
implicated in successful claims (data obtained via freedom of information
act) in SAH.
Their proposed rules would be likely to result in more cases of
'missed' SAH or of other important secondary causes of thunderclap
headache. The article unfortunately does not emphasise the importance of
measuring cerebrospinal fluid (CSF pressure) or considering alternative
diagnoses to SAH. Some alternative causes such as venous sinus thrombosis
can also be life threatening, and may elude diagnosis unless specific
imaging sequences are requested (eg CT or MRI venography).
3) Management of the suspected SAH patient also involves ensuring
that the process of investigation is correctly carried out.
Worryingly, one patient in our 2 year study was discharged by a
junior doctor (SHO grade) with negative oxyhaemoglobin results, though
without the bilirubin result- which was, later, found to be positive. The
patient was found to have had an aneurysmal bleed. This clearly implies a
need for greater training for medical staff involved in the management of
such patients. However, the turnover of junior doctors in most hospitals
is high and redesigning clinical processes to reduce reliance on junior
doctor's knowledge, is arguably more likely to reduce adverse outcomes.
The professional bodies for specialities involved in care of this patient
group might consider debating the issue and developing nationally agreed
joint guidelines. The British Association for the Study of headache(1)
and the College of Emergency Medicine(2) are currently working on such an
approach
Rapid Response:
Management of Thunderclap Headache
Sir
We read with interest the recent article by J Perry et al. The
authors correctly state that the proposed rules would need validation in
clinical practice. We would like to make three points.
1) We would like to share the results of a 2 year study we have
conducted. It indicates that application of their proposed rules would
result in missed diagnoses of SAH (subarachnoid haemorrhage).
Our study was performed across 4 hospitals (one tertiary centre with
neurosurgery and neuroradiological facilities, two teaching hospitals and
one district general hospital), covering two counties of England, between
2006-2008.
We examined the outcome of patients receiving lumbar puncture to
exclude a SAH, following a 'negative' scan. 372 sets of patient notes
were analysed. There were 6 cases (1.6%) of proven SAH (CSF bilirubin
positive, other causes excluded). In five patients the onset of headache
was instantaneous, or over minutes. In one patient the headache was of
gradual onset, with confusion and drowsiness over days (proven SAH
secondary to basilar aneurysm). One patient, admitted via the emergency
department was 21 years old. This patient would not have been identified
by the proposed rules. Interestingly, in only 50% (3 of the 6 proven
cases) was SAH the primary suspected diagnosis (although it was obviously
considered an important diagnosis to exclude given the history). Our
study highlights the importance of having a low threshold for
investigation of thunderclap headache.
2) Analysis of the National Health Service litigation agency database
from 1995-2002 identified emergency medicine as the most common speciality
implicated in successful claims (data obtained via freedom of information
act) in SAH.
Their proposed rules would be likely to result in more cases of
'missed' SAH or of other important secondary causes of thunderclap
headache. The article unfortunately does not emphasise the importance of
measuring cerebrospinal fluid (CSF pressure) or considering alternative
diagnoses to SAH. Some alternative causes such as venous sinus thrombosis
can also be life threatening, and may elude diagnosis unless specific
imaging sequences are requested (eg CT or MRI venography).
3) Management of the suspected SAH patient also involves ensuring
that the process of investigation is correctly carried out.
Worryingly, one patient in our 2 year study was discharged by a
junior doctor (SHO grade) with negative oxyhaemoglobin results, though
without the bilirubin result- which was, later, found to be positive. The
patient was found to have had an aneurysmal bleed. This clearly implies a
need for greater training for medical staff involved in the management of
such patients. However, the turnover of junior doctors in most hospitals
is high and redesigning clinical processes to reduce reliance on junior
doctor's knowledge, is arguably more likely to reduce adverse outcomes.
The professional bodies for specialities involved in care of this patient
group might consider debating the issue and developing nationally agreed
joint guidelines. The British Association for the Study of headache(1)
and the College of Emergency Medicine(2) are currently working on such an
approach
s.harikrishnan@nhs.net
(1) http://www.bash.org.uk/
(2) http://www.collemergencymed.ac.uk/
Competing interests: No competing interests