CASE REPORTS

SPONTANEOUS INTRACRANIAL HYPOTENSION
RESULTING IN COMA: CASE REPORT
Faisal T. Sayer, M.D., M.Sc.
Department of Neurosurgery,
Lund University Hospital,
Lund, Sweden

Mikael Bodelsson, M.D., Ph.D.
Department of Anaesthesia and
Intensive Care,
Lund University Hospital,
Lund, Sweden

Elna-Marie Larsson, M.D., Ph.D.
Department of Radiology,
Lund University Hospital,
Lund, Sweden

Bertil Romner, M.D., Ph.D.
Department of Neurosurgery,
Lund University Hospital,
Lund, Sweden
Reprint requests:
Faisal T. Sayer, M.D., M.Sc.,
Department of Neurosurgery,
Lund University Hospital,
221 85 Lund, Sweden.
Email: Faisal.Sayer@neurokir.lu.se
Received, May 11, 2005.
Accepted, March 8, 2006.

OBJECTIVE AND IMPORTANCE: Spontaneous intracranial hypotension is a potentially
severe condition characterized by a distinct clinical picture due to low cerebrospinal
fluid pressure. Although coma has been previously reported as a presentation of this
condition, this is the first report where misdiagnosis of this condition and unwarranted
surgery lead to coma.
CLINICAL PRESENTATION: A 62 year-old man presented with a history of headache
and cranial MRI showed bilateral chronic subdural haematomas. Following evacuation of the haematoma, the patient’s condition deteriorated into a state of profound
depression of consciousness. Repeated cranial CT showed intracranial air and intracranial pressure monitoring showed negative recording. Spinal MRI demonstrated epidural
CSF leaks at the middle and lower thoracic levels.
INTERVENTION (OR TECHNIQUE): Epidural blood patch resulted in almost immediate improvement in the patient’s condition and he was fully awake 24 hours later.
CONCLUSION: This case report expands the presently known clinical spectrum of this
uncommon and generally benign illness.
KEY WORDS: brain sagging; CSF hypovolaemia.; spontaneous intracranial hypotension; subdural
haematoma
Neurosurgery 58:E204-E205, 2006

DOI: 10-1227/01.NEU.0000219843.34356.EE

S

pontaneous intracranial hypotension
(SIH) is an increasingly recognized cause
of orthostatic headache, and it is a differential consideration in patients who present
with nontraumatic spontaneous subdural
hematoma. We document a case of SIH, where
evacuating the associated chronic subdural
hematoma was complicated by obtundation
related to diencephalic compression. We discuss the appropriate diagnosis and management of SIH and demonstrate that the prognosis of the SIH seems good if appropriately
diagnosed and treated in time before ensuing
irreversible CNS damage.

CASE REPORT
A 62 year-old, previously healthy man, presented to his General Practitioner with three
months history of headache, fatigue and progressive slowness in thinking and speech. The
headache was described as dull, diffuse and it
was accentuated by physical stress. There was
no relation between the headache and posture.

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He also complained of a mild short-term memory deficit of approximately the same duration.
The patient also reported some degree of
imbalance, but it was not sufficient to affect
the gate and he did not need any support during walking. Further penetration of previous
medical history revealed two months history
of chronic cough, ascribed to allergy, approximately 6 months prior to presentation. There
was no history of trauma or head injury.
Radiological evaluation, within the same week
of presentation, with MRI and CT scan of the
brain showed extensive 10 mm thick bilateral
fronto-parietal chronic subdural haematomas
causing effacement of the sulci and compression of the lateral ventricles (Fig.1). On MRI, a
few mm descent of the tonsils below the foramen magnum was present (Fig. 1a), which was
interpreted to be secondary to the mass effect
of the haematomas. In addition, there was mild
diffuse dural enhancement (Fig. 1b). Three
days later, the patient was admitted to the
department of neurosurgery at Lund
University hospital on (Day 1). The patient

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SPONTANEOUS INTRACRANIAL HYPOTENSION AND COMA

A

B

A

B

C
FIGURE 1. Preoperative MRI. T1weighted sagittal image (A) shows a
few mm descent of the tonsils below
the foramen magnum. T1-weighted
contrast enhanced coronal image (B)
and T2-weighted transverse image
(C) show bilateral chronic subdural
haematomas with effacement of the
sulci and compression of the lateral
ventricles. In addition, there is mild
diffuse dural enhancement (b).

displayed GCS 13 and answered questions correctly but with
latency. Romberg’s sign was positive with tendency to fall
backwards. No other neurological deficits were found on
admission. Standard physical examination, including blood
pressure and pulse, as well as blood chemistry was normal. The
following is a chronological outline of events during the patient
stay at our department:
On Day 2, the patient was operated with burr hole irrigation
(evacuation) of the chronic subdural haematoma on the left
side. In the initial postoperative period, the patient recovered
uneventfully. However, on Day 4, the patient was tired again
(GCS 13) and a new CT scan showed intracranial air frontally
ipsilateral to the surgical evacuation (Fig. 2a). The patient was
kept under observation and his level of consciousness fluctuated between GCS 12 and 14. A new CT scan on Day 6 showed
no increase of the intracranial air, however, the patient deteriorated further to a semi-comatose state (GCS 8). He was transferred to the neurosurgical ICU and an acute EEG the next day
showed no evidence of epileptic activity.
On Day 8, the patient was re-operated with evacuation of the
intracranial air through the same burr hole on the left side.
Initially the patient’s condition improved and he was more
awake (GCS 14), but relapsed after 2 hours to GCS 8. A new
acute CT scan showed an increased amount of intracranial air
on the left side and the patient was re-operated the same night
with evacuation of the intracranial air through the same burr
hole. However, after this third operation, the patient remained
in a GCS 8 state.
The following day, a new CT scan showed even more intracranial air in the bilateral frontal regions, and this intracranial

NEUROSURGERY

FIGURE 2. CT after the first operation (A) shows intracranial air frontally
ipsilateral to the surgical evacuation. CT after the third operation (B) shows
an increased amount of intracranial air, now in the bilateral frontal regions
with mass effect on the frontal lobes.

air accumulation caused significant mass effect with about 2 cm
dorsal displacement of the frontal lobes (Fig. 2b). The patient
was operated acutely on the same night with a bi-frontal craniotomy, evacuation of the intracranial air and inspection of the
floor of the anterior fossa for any possible source of air leak. No
source of leak was identified. The patient’s condition was
unchanged during the following days (GCS 8).
An MRI examination of the brain on Day 12 showed a thin
residual right-sided subdural haematoma and a left-sided subdural fluid-collection with effacement of the sulci of the convexities (Fig. 3). The previously noticed intracranial air had disappeared completely. In addition, this second MRI showed
caudal displacement of the mesencephalon, pons and (Fig. 3a).
Some degree of compression of the pons against the clivus was
seen. The cerebellar tonsils were also herniated through the
foramen magnum with progression compared with the preop-

A

B

FIGURE 3. MRI after the fourth operation. The T1-weighted sagittal image
shows caudal displacement of the mesencephalon, pons and medulla (A).
Some degree of compression of the
pons against the clivus is seen. The cerebellar tonsils are also herniated through
the foramen magnum with progression compared with the preoperative MRI.
The T2-weighted transverse image (B) shows a thin residual right-sided subdural haematoma and a left-sided subdural fluid-collection with effacement of
the sulci of the convexities. The intracranial air has disappeared.

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SAYER ET AL.

erative MRI. There were no signal changes in the brain stem
that could explain the deterioration of the level of
consciousness.
On Day 13, the patient’s condition deteriorated further to
GCS 7 and he was intubated and a catheter was inserted into
the lateral horn of the right ventricle to monitor the intracranial
pressure. When the ventricular catheter punctured the lateral
ventricle, the CSF came out clear and under low pressure. The
continuous registration of the intracranial pressure was always
below zero (⫺50 to ⫺90 mm H2O). Because of the negative
intracranial pressure and the MRI findings, spontaneous
intracranial hypotension (SIH) was suspected.
On Day 15, whole spine MRI revealed an extradural fluid
collection ventral to the spinal cord at C6-T1 and a similar collection dorsal to the spinal cord at the levels T1-T12 (Fig. 4).
This fluid collection had the same signal intensity as CSF. No
definitive source of CSF leak was identified. The clinical picture, negative ICP and radiological findings confirmed the
diagnosis of SIH.
An epidural autologous blood patch (30) ml was placed,
under x-ray guidance after injection of 3 ml of contrast, in the
epidural space at the levels L3-L4. Approximately 1 hour after
placing the blood patch, the ICP started to increase and about
two hours later, the ICP reached 140 mm H2O and the patient
was awake and obeying orders (GCS 13). The patient was kept
sedated until the next day and extubation the next morning
was uneventful. The patient quickly regained full consciousness. No residual neurological deficit was observed. On Day 21
the patient was sent to the referring hospital and was thereafter
discharged home.

A

B

DISCUSSION
In 1938, Schaltenbrand described a syndrome of spontaneous
positional headache with neck stiffness, nausea, vomiting, tinnitus, and vertigo in patients found to have low CSF pressure.
Schaltenbrand called this condition spontaneous aliquorrhea
and postulated that it can be due to occult dural tear, overabsorption of CSF, or decreased CSF production (26). The SIH is
now a recognised syndrome characterized by postural
headaches and CSF hypovolemia (5). The mean age of the
patients in was 43 years with some degree of female predominance (7).
The most common symptom of SIH is insidious onset of
orthostatic headache, which often evolves into chronic daily
headache. The headache associated with SIH is probably
caused by
dilatation of the cerebral veins and meningeal vasculature, or
it may be a consequence of the displacement of pain-sensitive
structures secondary to low CSF pressure; or both factors (27).
Other symptoms may include visual field deficits, transient
visual obscuration, facial numbness, sixth-nerve palsy, vertigo,
tinnitus, nausea, vomiting, and rarely stupor, cervical myelopathy, and Parkinsonism (5, 19, 22, 23). Progressive personality
and behaviour changes with memory loss may also occur (12).
Although uncommon, coma has been reported as a presentation of SIH (7, 9, 18, 31).
The diagnosis of SIH requires a high degree of suspicion. A
documented low CSF pressure (60 mm H2O) in the absence of
history of dural injury or tear (such as following lumbar puncture, back trauma, or operative procedures) is mandatory to
establish such diagnosis (25). When SIH is suspected, MRI of
the brain and spine are the investigations of choice. If MRI of
the spine is normal, radioisotope cisternography and/or CTmyelography are performed to detect CSF leakage.

MRI Findings
Typical brain MRI findings suggestive of SIH include:
1) Subdural effusions (10% of cases) due to rupture of bridging
veins caused by the decrease in CSF volume and downward
displacement of the brain (10).
2) Diffuse thickening of the meninges (also known as pachymeningitis) and meningeal contrast enhancement (3).
3) Obliteration of basilar cisterns, descent of midline structures
and flattening of the pons against the clivus (16).
Sayer, Faisal T.
4) Mild tonsillar descent is one of the cardinal signs of SIH (18).

FIGURE 4. MRI of the thoracic spine after the fourth operation. 3D sagittal
(A) and transverse (B) gradient echo images reveal an extradural fluid collection ventral to the spinal cord at C6-T1 and a similar collection dorsal to the
spinal cord (arros) at the levels T1-T12.

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The dural enhancement is the most common and probably
the earliest MRI manifestation of S.I.H., while subdural fluid
collections and descent of the brain are indicators of a more
severe hypotensive state (2).
Whole spine MRI may show varying degrees of shrunken
dural sac, expanded extradural space with CSF accumulation
and/or delayed homogeneous enhancement, and distended
epidural venous plexus (4). In the majority of cases, no structural

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SPONTANEOUS INTRACRANIAL HYPOTENSION AND COMA

lesion as a cause of CSF leak is identified and small tears in
nerve root sleeves are considered responsible. Although MRI
may not show the direct site of the leak, the location of the
spinal fluid collection may correspond to the region of CSF
leakage (i.e. cervical, thoracic or lumbar) (24).

Radioisotope Cisternography
Radioisotope cisternography with technetium-99m-human
serum albumin is useful to document and localize spontaneous
cerebrospinal fluid leakage along the neuraxis (13).

CT Myelography
On 3D CT myelography, the site of leakage may be depicted,
which may assist targeted epidural blood patch under the
guidance of fluoroscopy (10).
The choice of treatment will depend on whether a documented CSF leak is found or not. If no specific CSF leak is
found, then a short course of steroid medications, orally administered caffeine and epidural or intrathecal saline infusion may
be considered (1,20). If this has no effect or if the patient deteriorates, then epidural blood or fibrin glue patch should be
employed as an attempt to seal the CSF leak (14, 17, 30). If
these conservative measures fail and a dural defect have been
demonstrated to be the underlying cause of the CSF leak, surgical repair of the defect should be considered. The follow-up
of our patient, as well as the accumulated literature, indicate
that a subduro-peritoneal shunt, used by Whiteley et al. (31),
plays no role in the management of SIH. Although a patient
death was reported previously (11), the prognosis of the SIH
seems good if appropriately diagnosed and treated in time
before ensuing irreversible CNS damage.
In our patient, the diagnosis of SIH was not made until he
had been operated upon with evacuation of the subdural effusion and subsequently been reoperated three times with evacuation of intracranial air. This case should illustrate the value of
establishing a list of differential diagnosis even in a seemingly
routine and straightforward case like chronic subdural
haematoma. Another lesson is that one should not be dogmatic
about the diagnosis and this should be strongly discouraged
since it can lead to disastrous consequences.
In retrospect, the initial MRI should have given some suspicion of intracranial hypotension. However, the subdural effusions with mass effect on the lateral ventricles were considered
to be the main finding. The colour and consistency of the fluid
evacuated at the time of initial surgery suggested that it was a
hygroma and not a chronic subdural haematoma. Another
observation was that when the dura was opened, the evacuated
fluid was not under high pressure. These observations where
neglected initially and this has contributed to the delay in
establishing the diagnosis of SIH.
The low intracranial pressure, later proven by intracranial
pressure monitoring, could explain this accumulation of
intracranial air. Managing the patient in flat position for 24
hours after surgery did not reduce the intracranial air accumulation. Our patient had no clinical history of trauma, but his

NEUROSURGERY

chronic cough may have caused a dural tear with subsequent
CSF leakage (21). The state of altered level of consciousness
that the patient displayed was probably due to downward displacement of the brain and compression of the brain stem
against the clivus. The fact that the patient showed dramatic
and rapid clinical response to the lumbar epidural blood patch
could indicate that the redistribution of the blood in the
epidural space is faster than expected.

CONCLUSION
Early diagnosis of SIH is important in order to avoid unnecessary and potentially harmful evacuation of the associated
subdural effusions. A straightforward case such as bilateral
chronic subdural haematomas can turn into a nightmare if the
history and radiological examination is not reviewed thoroughly before surgery.

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