Keywords
Meckel cave - arachnoid cyst - petrous apex cephaloceles - trigeminal neuralgia -
percutaneous treatment
Palavras-chave
cavum de Meckel - cisto aracnoide - cefalocele do ápice petroso - neuralgia do trigêmeo
- tratamento percutâneo
Introduction
Arachnoid cysts are benign intracranial lesions that account for 1% of nontraumatic
intracranial lesions.[1]
[2] They are usually located in the middle fossa, but can be found in other locations
- such as the suprasellar, the posterior fossa, the interhemispheric, the quadrigeminal
cistern and the cerebral convexity. They are usually asymptomatic lesions, but may
become symptomatic depending on location and size.[3] There are several treatment options, including endoscopic or microsurgical fenestration,
microsurgical excision and cyst shunt. We present a case of symptomatic arachnoid
cyst in a very rare location that was treated by a strategy not described elsewhere.
Case Report and Surgical Strategy
A 54-year-old female was admitted in our service with trigeminal neuralgia in the
territories of the ophthalmic and maxillary trigeminal branches. She had a history
of radiofrequency rhizotomy treatment 6 years before, and at that time, the patient
presented improvement and good pain maintenance control with carbamazepine 400 mg
a day. Ten months before seeking assistance, the patient recurred and experienced
pain progression, which required successive increases in carbamazepine dosage up to
900 mg a day – dose to which she presented adverse reactions. Due to recurrence and
worsening of the clinical condition, propaedeutic were requested. The magnetic resonance
imaging (MRI) showed dilatation of the right Meckel cave (MC) with extension to the
petrous apex. The lesion presented as hyperintense on T2-weighted imaging, hypointense
on T1-weighted imaging ([Figure 1]); suppression of the signal in the T2-weighted fluid-attenuated inversion recovery
and absence of diffusion restriction on diffusion weighted imaging – description compatible
with arachnoid cyst. There were no neurovascular conflicts or other lesions associated
with the trigeminal nerve topography. Owing to daily episodes of excruciating pain
and intolerance to drug treatment, surgical treatment was chosen.
Fig. 1 Meckel cave (MC) arachnoid cyst on magnetic resonance imaging (MRI). (A) T2-weighted MRI image showing right MC dilatation with cerebrospinal sign (arrow).
(B) T1- weighted MRI image showing right MC dilatation (arrow).
Percutaneous puncture of the cyst through the foramen ovale with injection of intracystic
fibrin sealant was performed. The patient did not tolerate the sedation, so the procedure
took place under general anesthesia. A 20-Gauge spinal needle was inserted through
the ascending extraoral transoval route guided by lateral incidence fluoroscopy.[4] The introduction pathway started 3 cm lateral to the labial commissure and ascended
until the intersection point between the coronal plane 3 cm anterior to the tragus
and the sagittal plane of the pupil. After touching the skull base, the needle was
directed under fluoroscopy to the foramen ovale, using as reference point the clivus
intersection with the petrous pyramid. After entrance, the position of the needle
was confirmed by fluoroscopy ([Figure 2A]) and through cerebrospinal fluid (CSF) leakage through its lumen ([Figure 2B]). On account of active CSF drainage after the puncture, we chose not to inject contrast.
Then 2 mL of Tissucol was injected and the needle was removed. The patient woke up
from anesthesia with pain improvement and was discharged asymptomatic the next day.
The MRI performed on the first postoperative day revealed reduction of the cyst dimensions
and partial filling of the cyst by T2-weighted hypointense material extending through
the cisternal segment of the trigeminal nerve ([Figure 3]). After 12 months of follow-up, tapering of carbamazepine dose was achieved and
the patient remained pain-free using only 400 mg a day.
Fig. 2 Surgical technique. (A) Fluoroscopy-guided foramen ovale puncture. Note the tip of the needle in the intracranial
compartment (arrow). (B) Puncture point 3 cm lateral to lip rhyme. Note the leakage of cerebrospinal fluid
through the needle (arrow).
Fig. 3 Postoperative T2 -weighted magnetic resonance imaging showing partial filling of
the cyst by with hypointense material (white arrow) extending through the cisternal
segment of the trigeminal nerve (black arrow).
Discussion
Arachnoid cysts are collections of intracranial CSF surrounded by arachnoid layers.
They can be primary or secondary. The primaries are benign malformations originated
from arachnoid division during development resulting in anomalous CSF collections.
The secondary ones are less common and are associated with neoplasms, infections,
bleeding, trauma or surgery.[2]
[3] Depending on their location and size, arachnoid cysts may become symptomatic.
In a literature review, we found only eight cases reported as MC arachnoid cyst ([Table 1]).[2]
[5]
[6]
[7]
[8]
[9]
[10]
[11] The average age of the patients was 41 years old – with a range from 1 to 58 years
old – and there was a female predominance (5 out of 8). The most affected side was
the right side (five out of eight). In all but one case, there was trigeminal neuralgia
in 1 or more branches territories, associated or not with symptoms of other cranial
pairs, such as diplopia, vertigo, and hearing loss. The patient in whom no neuralgia
was reported was a 1.5-year-old child with exophthalmos and diplopia.[10] In only three cases the lesion was referred to as restricted to the MC, and in one
of these, no MRI was performed and the lesion was not described in details in the
article.[10] We can conclude that MC cysts tend to extend to adjacent regions, especially to
the petrous apex - as occurred in the case reported in the present paper.
Table 1
Cases Reported in the Literature
|
Author
|
Age (years old), gender
|
Symptoms
|
Location, side
|
Treatment
|
|
Wörner et al
[5]
|
44, M
|
Dysesthesia in V3, vertigo and diplopia
|
Meckel cave, CPA, R
|
Open resection
|
|
Batra et al
[6]
|
55, F
|
Pain and paresthesia in V3
|
Petrous apex, Meckel's cave, R
|
Open fenestration
|
|
Bigder et al
[2]
|
57, F
|
Pain in V2, temporal muscle atrophy and hemifacial paresthesia
|
Meckel cave, L
|
Percutaneous drainage
|
|
Fois et al
[7]
|
42, F
|
Sensorineural hearing loss and neuralgia
|
Meckel cave, petrous apex, B
|
Medication
|
|
Jacob et al
[8]
|
32, F
|
Diplopia and pain in V1
|
Meckel cave, R
|
Spontaneous resolution
|
|
Grasso et al
[9]
|
40, M
|
Neuralgia in V2-V3
|
Meckel cave, middle fossa and greater wing of sphenoid, L
|
Medication
|
|
Beck et al
[10]
|
1, M
|
Exophthalmia and diplopia
|
Meckel cave, R
|
Open resection
|
|
Jelsma et al
[11]
|
58, F
|
Neuralgia and hemifacial hypoesthesia
|
Meckel cave, petrous apex, R
|
Open fenestration
|
Abbreviations: B, bilateral; CPA, cerebellopontine angle; F, female; L, left; M, male;
R, right; V1, ophthalmic trigeminal branch; V2, maxillary trigeminal branch; V3, mandibular
trigeminal branch.
Of the reported cases, two were treated with drugs alone; five were treated surgically
and one had spontaneous resolution. Of the five surgically treated patients, four
underwent craniotomy treatment and only one underwent percutaneous treatment with
cyst aspiration through the foramen ovale puncture.[2] In this patient, the control MRI presented cyst persistence and the author attributed
the improvement to possible rhizotomy by injected contrast or needle injury.[2] Moreover, these data show the importance of preoperative differential diagnosis
by MRI of lesions in the MC because in all patients undergoing craniotomy, the diagnosis
of arachnoid cyst was made intraoperatively, excluding the possibility of less invasive
treatment.[5]
[6]
[10]
[11]
There are reports of petrous apex cephaloceles. These are uncommon lesions, rarely
described in the literature and sometimes radiologically indistinguishable from arachnoid
cysts of the MC. They are considered by some authors to be the same entity[2]
[8]. Defined as cystic lesions with a cerebrospinal fluid-like sign at the petrous apex
that protrude through the posterolateral wall of the MC, they can be composed of dura
mater and arachnoid or just arachnoid – being described as meningoceles and arachnoid
cysts.[12]
[13]
[14]
[15] However, dilatation may be restricted to the petrous apex without dilatation of
the MC and they are usually not associated with trigeminal neuralgia, but with sixth
cranial nerve neuropathy and otological symptoms.[8]
[12] Possibly, they are part of the same spectrum of disease of the arachnoid cyst in
the MC differing only in presentation and progression.
Meckel cave arachnoid cysts are likely to progress and become symptomatic due to their
communication with the subarachnoid space and a unidirectional valve mechanism that
only allows CSF entry. This communication between the cyst and the CSF system may
allow the transmission of pulsations to the nerve and cyst enlargement causing trigeminal
neuralgia by a mechanism similar to neurovascular compression.[9]
We describe a noninvasive, effective and safe technique for the treatment of Meckel
cave arachnoid cysts. We did not find in the literature a description of the same
strategy. The improvement mechanism with this technique is probably the interruption
of the communication between the cyst and the cerebrospinal fluid system, which prevents
the transmission of pulsations to the nerve and enlargement of the cyst.
Conclusion
Meckel cave arachnoid cysts are rare lesions in which preoperative differential diagnosis
is very important for proper surgical planning and for individualized treatment with
less morbidity. Filling the cyst with fibrin sealant by percutaneous puncture was
effective for symptomatic control of the patient with minimal associated morbidity.
We consider that this technique should be considered for surgical treatment of this
lesion.
