Reply to the report by Mactier et al
We read with interest the report by Mactier et al (1). The cases
reported by Rennick et al clearly demonstrated that, in children, a normal
CT scan does not exclude raised intracranial pressure, and a lumbar
puncture can result in coning (2). Dr Abernethy, in his letter, correctly
states this is a common misconception (3). We would wish to emphasise that
this misconception also applies to adults as well as children, as the
following case illustrates.
A sixty one year man was admitted to this hospital with acute
confusion. The general practitioner said the patient had complained of
sore throat, headache, and arthralgia, and he had been treated for two
days with penicillin V. On examination the patient had neck stiffness with
a Glasgow coma scale (GCS) of 10 (eyes opened spontaneously, flexion to
pain, incomprehensible verbalization). There was no rash or focal signs.
He was treated with intravenous cefotaxime. A CT scan was performed which
was reported as normal
A lumbar puncture was performed immediately after the scan. The
opening pressure exceeded 40 cm. Over the next few minutes the GCS fell
to 7, and the left pupil became fixed and dilated. His breathing became
irregular. The intensive care anaesthetist was called urgently. The
patient was anaethetised, intubated and hyperventilated on ward, and given
20% mannitol. Both pupils became equal. On the intensive care unit a
Codman parenchymal strain gauge intracranial pressure (ICP) bolt was sited
and the entry pressure recorded at 50 mm Hg. The ICP responded over next
24 hours to medical management, and the patient was extubated after 48
hours. He subsequently made full recovery. Ironically, the CSF was
unremarkable. A meningococcus isolated on blood cultures.
We would agree with Mr Cooke and Dr Patterson that intracranial
pressure monitoring is invaluable in the management of many patients, and
that there is a shortage of neuroscience intensive care beds (4). However,
we would disagree that such monitoring should only be performed in a
neurosurgical intensive care unit. We have employed intracranial pressure
monitoring in our District General Hospital since 1992, most recently with
the Codman parenchymal strain gauge, with no complications (5). The
cerebral perfusion pressure is displayed continuously, and although CSF
cannot be drawn off, other medical measures to reduce intracranial
pressure can be monitored. The bolt also assists in weaning from
There seems little doubt that the lumbar puncture precipitated this
patient's sudden deterioration, and that the information it gave was
unhelpful. The diagnosis of raised intracranial pressure is clinical, not
radiological. Regardless of the patients age, if there is impairment of
consciousness a lumbar puncture must not be performed, even if the CT scan
is normal. If meningitis is suspected prompt antibiotic treatment must
commence immediately. Alternative specimens (including blood for
polymerase chain reaction, and nasal swabs), can be obtained which do not
put the patients life at risk.
Dr M Srivastava - Specialist Reg in Anaesthesia
Dr T J Parke - Consultant in Anaesthesia and Intesive Care
Dr C Waldmann - Director, Intensive Care Unit
Intensive Care Unit,
Royal Berkshire Hospital,
Reading, RG1 5AN
1 Mactier H, Galea P, McWilliam R. Acute obstructive hydrocephalus
complicating bacterial meningitis in childhood. BMJ 1998;316:1887-9.
2 Rennick G, Shann F, de Campo J. Cerebral herniation during
bacterial meningitis in children. BMJ 1993;306:953-5.
3 Abernethy L. Neuroimaging has its limitations. BMJ 1998;318:124
4 Cooke RS, Patterson V. Hydrocephalus was probably non-obstructive.
BMJ 1998;318:124 (c).
5 Waldmann C, Thyveetil D. Management of head injury in district
general hospital. Care of the Critically Ill 1998;14(2):65-70
Competing interests: No competing interests