Neurosurg. Rev.
17 (]994) 229 232

A r a c h n o i d cyst with traumatic intracystic h e m o r r h a g e
unassociated with subdural h e m a t o m a
Faruk Ildan, Erdal Cetinalp, Hiieyin Ba~datoglu, Biilent Boyar, and Ziya
Uzuneyiio~lu
Cukurova University, School of Medicine, Department of Neurosurgery, Balcali,
Adana, Turkey

Abstract
Arachnoid cysts of the middie cranial fossa may manifest themselves in several different ways. Most often
they remain asymptomatic and are only diagnosed incidentally on computed tomography or at autopsy. When
they are symptomatic, headache, nausea, vomiting and
seizares are most common in the patients with increased
intracranial pressure. Increased intracranial pressure is
caused by the ball-valve mechanism of the cyst's membrane which is in communication with the general subarachnoid space or arachnoid cells which contain specialized membranes and enzymes which have secretory activity. A significant number of middle cranial fossa
arac]hnoid cysts are associated with subdural hematoma
which may, in turn, be associated with intracystic hemorrhage. We report an unusual case with posttraumatic,
isolated intracystic hemorrhage of the arachnoid cyst in
the sylvian area without subdural hematoma.

Keywords: Arachnoid cyst, intracystic hemorrhage,
middle fossa, subdural hematoma.

1 Introduction
Arachnoid cysts are intra-arachnoid collections of
cerebrospinal fluid (CSF). They can be found intracranially at any location adjacent to, and frequently communicating with, the subarachnoid
space that commonly occurs in the middle fossa
[20]. They can cause neurological deficit by expanding and compressing the surrounding normal
tissue. They can also obstruct CSF flow and produce such symptoms as developmental delay,
craniomegaly, seizures, and headache [1, 10, 21].
Other specific symptoms and signs vary depend9 1994 by Walterde Gruyter& Co. Berlin 9New York

ing upon the location. These cysts are frequently
discovered incidentally during radiographic evaluation for an unrelated complaint. Arachnoid
cysts located in the middle fossa have been well
described in the literature. They are often considered to be a separate clinical entity [23]. Many of
the cysts in the middle cranial fossa are asymptomatic and require no immediate treatment.
However, reports have drawn attention to the predisposition of the cyst to develop an associated
subdural hematoma [13, 18], which may, in turn,
be associated with intracystic hemorrhage [3, 17].
The occurence of intracystic hematoma may be
more frequent than has been suggested [18]. Due
to its venous nature hematoma is nearly always
at a chronic stage when clinically manifested. We
report a patient who present 10 days after head
injury who manifested isolated intracystic hematoma of the middle fossa arachnoid cyst without
subdural hematoma. According to our findings a
case of isolated intracystic hemorrhage into the
arachnoid cyst of the middle cranial fossa without
subdural hematoma has not been reported in the
literature previously.

2 Case report
This 32-year-old man was admitted with a one
week history of right parietal headache, six days
vomiting, and increasing hemiparesia involving
the left side. Ten days previously, he had sustained a mild head injury. On clinical examination, bilateral papiledema and left hemiparesis

230
were found. Computerized tomography (CT) demonstrated a right middle fossa arachnoid cyst
with intracystic hematoma and mild compression
on the right frontal horn (Figure 1). Hemorrhage
was not noted anywhere in the subdural space. A
craniotomy was carried out immediately. A subdural membrane was found covering the floor of
the middle fossa and extending up over the convexity under greatly increased pressure. The outer
wall of this lining was removed totally after evacuation of the intracystic hematoma. The insula
was exposed with absence of the anterior portion
of the right temporal lobe. There was an inner
membrane in the depths of the cavity. The inner
wall could not be separated from the arachnoid
membrane covering the sylvian tissue. The exact
source of hemorrhage within the cyst could not
be seen. Postoperatively, the headache and vomiting were relieved. Clinical recovery was satisfactory and no residual neurological deficit resulted.
The membrane of the middle fossa cyst consisted
of slightly thickened arachnoid. Unfortunately
there were no specific histological findings which
can explain the cause of the bleeding.

3 Discussion

The subject of the origin and natural history of
intracranial arachnoid cysts is still controversial.
Hypothesis offered to explain the development of
arachnoid cysts include congenital malformation

Ildan et al., Cyst with hemorrhage
[21, 23], infection [4, 22], and increased intracranial pressure [14]. The relative prevelance
of these cysts in the pediatric population and the
absence of signs of trauma or inflammation in the
majority of the cases [2, 16, 22] suggest a congenital lesions which differ from traumatic or inflamatuar leptomeningeal cysts. Many histopathological studies with light and electron microscopes have definitely revealed that the outer and
inner walls of the arachnoid cysts consist of layers of arachnoid cells which unite with the normal
arachnoid at the margins of the cyst [8, 10].
Arachnoid cysts seem to increase in size by collection of CSF secreted through arachnoid cells
which contain specialized membranes and enzymes which have secretory activity rather than
unidirectional CSF flow (ball-valve trapping)
[10, 231.
Arachnoid cysts of the middle fossa are considered to be the most common group. They occur
most commonly in males under the age of 20,
however, may also occur at any age. The various
clinical manifestations of arachnoidal cysts of the
middle fossa have been well described; the most
common is headache. Much less commonly, seizures occur. Cysts in this location may deform
the surrounding bone by erosion or expansion.
When the cyst is large, the sphenoid ridge is elevated, and the greater wing remodels and displaces forward. However, such cysts can remain
asymptomatic throughout life [22].
Prior to the advent of CT, the diagnosis of arachnoid cysts were generally made by plain radiography or angiography of the skull. X-rays showed
thinning and bulging of the temporal squama, enlargement of the middle cranial fossa, elevation
of the lesser sphenoid wing. Angiography showed
an avascular space with the signs of displaced
vessels.
CT scans yield definite diagnosis of arachnoid
cysts. Arachnoid cysts in the sylvian area may
have a rectangular shape, probably as a result of
shortening of the temporal lobe and flattening of
the adjacent insula, as in our case [5].

Figure 1. CT scan after contrast enhancement showing
an intracystic hemorrhage of the arachnoid cyst in the
sylvian area without subdural hematoma.

Many reports have noted an inclination to develop an associated subdural hematoma and intracystic hemorrhage in patients with arachnoid cyst
of the middle fossa [3, 13, 17]. This was first
recognized by ROBINSON [22] and substantiated
Neurosurg. Re~ 17 (I994)

Ildan et al., Cyst with hemorrhage
by S~nTH and SMITH [23]. The event of intracystic hemorrhage may be more common than previously suggested. There has been no satisfactory
explanation for the susceptibility of patients with
an arachnoid cyst in the sylvian fissure to develop
subdural or intracystic hematoma. The postulated
explanations included: 1) after a minor trauma
flow changes within the CSF could be magnified
by the arachnoid cyst causing the rupture of the
bridging veins or vessels in the cyst wall, or 2)
since the arachnoid cyst is less compliant than
normal brain, reduced intra-calvarial cushioning
is present [18].
CT usually delineates the well-circumscribed,
low density arachnoid cyst, but the hemorrhage
into the cyst can always increase its density. For
this reason intracystic hematomas are usually
easy to identify in the early period. Subacutely,
the clot may contract, increasing further in its
density, but the period is short-lived. Then proteolysis begins and hematoma protein is degraded
and absorbed [7]. After the state of isodensity has
been reached the detection becomes difficult [12,
15]. Injection of intravenous contrast material
may allow description of the subdural membrane
between the cyst and the subdural hematoma.
Arachnoid cysts of the middle fossa may disappear spontaneously [6], even in the presence of

231
intracystic hemorrhage [11, 12]. Asymptomatic
araclmoid cysts without signs o f increased intracranial pressure and focal neurological signs
should be treated non-surgically. A surgical approach can only be suggested for cases with considerable space occupation along with midline
shift or focal neurological signs [9, 19]. Although
drainage of the fluid of the cyst without excision
of its membrane has been considered to be effective in the majority o f the cases, exision of the
cyst rather than simple drainage or shunting procedure as proposed by AUER et al. [3] has been
considered as the most effective treatment.
We report an unusual case with isolation intracystic hemorrhage of the arachnoid cyst of the middle cranial fossa without subdural hematoma ten
days after trauma. Although the situation in
which there is both subdural and intracystic hematoma has been reported frequently a case o f
isolated intracystic hemorrhage has not been reported so far, according to our knowledge.
We believe that arachnoid cyst o f the middle cranial fossa without subdural hematoma following
trauma is a specific pathological entity. Clinicians
should always be alert to the possibility of isolated intracystic bleeding in patients with middle
fossa araclmoid cysts.

References
[I] AICARD1 J, F BAUMAN: Supratentorial extracer-

ebral cysts in infants and children. J Neurot Neurosurg Psychiatry 38 (1975) 57-68
[2] ANDERSONFM, HD SEOALL,WL CATON:Use of
computerized tomography scanning in supratentorial arachnoid cysts. A report on 20 children and
four adults. J Neurosurg 50 (1979) 333-338
[3] AIDER LM, B GALLHOFER,G LADURNER, WD
SAOER, F HEPPNER, H LECHER: Diagnosis and
treatment of middle fossa arachnoid cysts and subdural hematomas. J Neurosurg 54 (1981) 366369
[4] BANNA M: Arachnoid cyst in the hypophyseal
area. Clin Radiol 25 (1974) 323-326
[5] BANNAM: Arachnoid cysts on computed tomography. AJR 127 (1976) 979-982
[6] BELTRAMELLOA, C MAZZA: Spontanous disappearance of a large middle fossa arachnoid cyst.
Smg. Neurol 24 (1985) 181-183
[7] BERGSTROM M, K ERICSON, B LEVANDE, P
SVENDSEN; Computed tomography of cranial subNeurosurg. Rev. 17 (1994)

dural and epidural hematomas. Variation of attenuation related to time and clinical events such as
rebleeding. J Comput Assist Tomogr 1 (1977)
449-455
[8] DI ROCCO C, M CALDARELL1,G DI TRAPANE IntratentoriaI araclmoid cysts in children. Childs
Brain 8 (1981) 119-133
[9] GALASSIE, G GAIST, G GIULIANI, E POZATTI:
Arachnoid cysts of the middle cranial fossa experience with 77 cases treated surgically. Acta Nem-ochir (Suppl) 42 (1988) 201-204
[10] Go KG, HJ HOUTHOFF,EH BLAAUW,P HAVINGA,
J HARTSUIKER:Arachnoid cysts of the sylvian fissure. Evidence of fluid secretion. J Neurosurg 60
(1984) 803-813
[11] HARA H, T [NOVE, K MATSUO, S KOBAYASHI,K
SUG~TA:Unusual computed tomographic findings
in a case of arachnoid cyst in the middle cranial
fossa. Surg Neurol 22 (1984) 79-82
[12] INOVET, T MATSUSHIMA,S TASHIMA,M FUKUI,K
HASUA: Spontaneous dissappearance of a middle

232
fossa arachnoid cyst associated with subdural
hematoma. Surg Neurol 28 (1987) 447-450
[13] LACOUR, R Tm~VOR,M CREY: Arachnoid cyst and
associated subdmal hematoma. Observations on
conventional roentgenographic and computerized
tomographic diagnosis. Arch Neurol 35 (1978)
84-89
[14] LITTLEJR, MR GOMEZ, CS MAC CARTY:Infratentorial arachnoid cysts. J Neurosurg 39 (1973)
380-386
[15] LUND ]~, M BUHL, T MILLETIC, V KNUDSEN: Isodense middle fossa arachnoid cyst and subdural
hematoma: a diagnostic problem on CT. J Neuroradiol 14 (1987) 89-93
[16] MENEZESAH, WE BELL, GE PERRET: Arachnoid
cysts in children. Arch Neurol 37 (1980) 168-172
[17] OLSEN NK, HHT MADSEN: Arachnoid cyst with
complicating intracystic and subdural hemorrhage.
RSntgen B1 43 (1990) 166-168
[18] PAGE A, RM PAXTON, D MOHAN: A reappraisal
of the relationship between arachnoid cysts of the
middle fossa and chronic subdural hematoma. J
Neurol Neurosm'g Psychiatry 50 (1987) 10011007
[19] RaFFEL C, JG McCOMB: To shunt or to fenestrate:
which is the best surgical treatment for arachnoid

Ildan et al., Cyst with hemorrhage
cysts in pediatric patients? Neurosurgery 23
(1988) 338-342
[20] R~NGACHARYSS, WATANABEI: UItrastructure and
pathogenesis of intracranial arachnoid cysts. J
Neuropathol Exp Neurol 40 (1981) 61-83
[21] RENGACHARY as, I WATANABE, c g BRACKETT"
Pathogenesis of intracranial arachnoid cysts. Surg
Neurol 9 (1978) 139-144
[22] ROBINSON RG: Congenital cysts of the brain:
arachnoid malformations. Progr Neurol Surg 4
(1971) 133-174
[23] SMITH RA, SMITH VA: Arachnoid cysts of the
middle cranial fossa. Surg Neurol 5 (1976) 2 4 6 252.
Submitted January 15, 1993. Accepted March 31,
1993.
Faruk ildan, M.D.
Cukurova University
School of Medicine
Department of Neursurgery
Balcali, Adana
Turkey

Neurosurg. Rev. 17 (1994)