Primary intracranial arachnoid cyst in the elderly: a survey on 39 cases

Suprasellar arachnoid cyst due to ectopic choroid plexus: case report

Arachnoid cysts (ACs) are malformations that account for about 1% of all intracranial lesions. The aetiology and progression of these lesions have been debated, with one possible explanation being the production of cerebro-spinal fluid (CSF) by ectopic choroid plexus (CP). To our knowledge, only seven cases of ACs incorporating CP have been reported, and we believe this to be the first reported case of a suprasellar AC containing ectopic CP. A 1-year-old boy presented with developmental delay and macrocephaly. MRI scan revealed hydrocephalus due to a suprasellar AC. An endoscopic ventriculocisternostomy was undertaken. Intra-operatively, intra-cystic, pink frond-like tissue resembling choroid plexus was identified. Histologically, the cyst wall was composed of fibrous tissue, with layered arachnoid cells, while the frond-like tissue was composed of papillary structures in keeping with normal choroid plexus tissue. We postulate that the rest of the ectopic CP may have been trapped within the double layered arachnoid fold of the diencephalic leaf of Liliequist's membrane which may drive the formation and development of certain suprasellar ACs.

[Symptomatic arachnoid cyst in an elderly patient who developed motor aphasia]

The patient was an 83-year-old woman with a history of breast cancer, distal right radial edge bone fracture, and cervical spine symptoms who had been diagnosed with an arachnoid cyst 9 years previously. She was examined by a nearby doctor, because of an approximately 1-year history of reduced verbal output; she also begun experiencing difficulties with walking. However, she was diagnosed with aging, a history of cervical spondylosis, and the effects of past fractures.At the time of this consultation, she was conscious and lucid, with mild right-sided hemiparesis, was unable to write, and had mild motor aphasia. Head magnetic resonance imaging revealed an arachnoid cyst (longer axis: 10 cm) in the left frontal lobe that did not take up contrast media. There was also a midline shift. The cause of the right hemiparesis and motor aphasia was probably compression of the left frontal lobe by the arachnoid cyst.We performed excision of the cyst wall by craniotomy and placed a cyst-peritoneal shunt under general anesthesia. At approximately one week after surgery, the patient was able to write and her motor aphasia improved. She was discharged 20 days after the operation.It is rare for an arachnoid cyst to increase in size after childhood. In the present case, surgical treatment led to a good outcome in an elderly patient with a symptomatic arachnoid cyst. Arachnoid cysts rarely increase in size. These cysts may become symptomatic in elderly people after lying clinically dormant for a long time.

Long-term Follow-up of a Multiloculated Arachnoid Cyst of the Middle Cranial Fossa

Arachnoid cysts are benign intracranial lesions that are typically diagnosed incidentally. We describe the case of a 56-year-old man who presented with a multiloculated arachnoid cyst of the middle cranial fossa that extended into the sphenoid sinus. The lesion was identified on computed tomography of the head, which had been obtained for an unrelated investigation. However, establishing a definitive diagnosis proved to be difficult. Because the cyst had caused extensive skull base erosion, the patient was managed conservatively with close observation. We report the radiographic progression of this lesion during more than a decade of follow-up, and we review the literature pertaining to the presentation, pathophysiology, and treatment of arachnoid cysts.

Symptomatic foramen of Magendie arachnoid cyst in an elderly patient: The second case report in the literature

Background

Arachnoid cysts are benign extra-axial lesions corresponding to 1% of intracranial expansive lesions. They are usually incidental findings in asymptomatic patients. Most cases are congenital, and when symptomatic are diagnosed in childhood or adolescence. Symptomatic arachnoids cyst in elderly patients is very rare. This report documents the second case in the literature of a symptomatic elderly patient with an arachnoid cyst located in the foramen of Magendie.

Case Description

A 68-year-old male had weakness in the lower limbs, imbalance, and gait disturbance for 3 years, associated with frequent falls. The patient complained of paresthesia in the upper right limb and right hemiface. An magnetic resonance imaging showed a massive cystic lesion in the posterior fossa in the foramen of Magendie. A median suboccipital craniectomy was performed, and the cyst was removed.

Conclusion

This case report adds to the literature the second case of a patient with a symptomatic arachnoid cyst in the posterior fossa successfully treated by surgery.

Intracranial ectopic choroid plexus cyst in a dog

A 4-year-old male Toy Poodle was presented with a history of status epilepticus. On presentation, neurological examination revealed a delay in postural reactions in the right pelvic limb. Magnetic resonance imaging showed a fluid-containing cystic lesion that compressed the mesencephalon, hippocampus, and amygdala. The cyst was surgically removed via left rostrotentorial craniotomy. The final diagnosis was an intracranial ectopic choroid plexus cyst. The patient has remained free of seizures for 18 months after surgery. This is the first case report of an intracranial ectopic choroid plexus cyst that was surgically removed in a dog.

Prepontine arachnoid cyst presenting with headache and diplopia: A case report study

Background:

Arachnoid cysts are found everywhere in cerebrospinal axis, most often in the middle cranial fossa. They are very rare in prepontine location.

Case Description:

In this study, we report a 26-year-old female presenting with a 3-month history of headache and diplopia. On physical examination, she had clinical manifestations of sixth cranial nerve palsy. Magnetic resonance imaging revealed a prepontine arachnoid cyst with extension into interpeduncular and suprasellar cisterns. Computed tomography scan demonstrated no evidence of hydrocephalus. The patient was treated surgically by endoscopic fenestration of the cyst with endonasal transsphenoidal approach. The cyst was opened to prepontine, interpeduncular, and suprasellar cisterns.

Conclusion:

Endoscopic endonasal fenestration of the cyst to adjacent cistern may be safe in prepontine arachnoid cysts with sellar and suprasellar extension; it may be effective and less invasive compare to transcranial approach.

Arachnoid cysts of the middle cranial fossa accompanied by subdural effusions--experience with 60 consecutive cases

BACKGROUND

Subdural effusions (SDEs) can complicate arachnoid cysts of the middle cranial fossa (ACMFs). While there is a consensus that at least in adults asymptomatic ACMFs should not be operated, those with concomitant subdural and/or intracystic effusions are clinically apparent in the majority of cases and should be surgically treated. But it remains unclear, which surgical procedure is best.

METHODS

Since 1980, 60 out of 343 patients with an ACMF presented with accompanying SDEs. Four categories of SDEs were differentiated radiologically. This collective was controlled in a follow-up study up to 60 months after conservative or operative treatment by clinical and radiological means.

RESULTS

In 54 of the 60 patients, we saw an indication for surgical treatment. Twenty-nine patients received a burr hole, 13 cases were treated by craniotomy, seven by endoscopical means, three patients underwent shunting and two combined procedures. Six patients were treated conservatively. An excellent final clinical outcome was observed in 55 cases. While craniotomy succeeded best to reduce the cyst volume in postoperative CT, the final clinical outcome did not differ significantly compared with burr hole trepanation.

CONCLUSIONS

Patients with small effusions can be treated conservatively in selected cases. Based on our experience, we prefer a differentiated therapy. As first procedure, burr hole and subdural drainage were performed, leaving the cyst alone, seeming sufficient for the majority of cases. Craniotomy or endoscopical means should be reserved as treatment of choice for special cases, depending on category and acuteness of SDE and size/localisation of the ACMF.

Arachnoid Cyst Confined to the Internal Auditory Canal—Endoscope-Assisted Resection: Case Report and Review of the Literature

BACKGROUND AND IMPORTANCE:

An arachnoid cyst confined to the internal auditory canal is a rare condition. Different pathogeneses are discussed, and a progressive enlargement of the cysts has been reported. This case illustrates the beneficial aspect of endoscopic assistance in microsurgical resection of this lesion.

CLINICAL PRESENTATION:

A slowly progressive hearing loss developed in a 35-year-old woman over 2 years; she reported experiencing tinnitus for 7 years. Magnetic resonance imaging revealed a cystic lesion in the internal auditory canal appearing hypointense on T1-weighted images and hyperintense on T2-weighted images, suggesting an arachnoid cyst.

INTERVENTION:

The cyst wall was fenestrated and partially resected in an endoscope-assisted microsurgical technique. Adherent vestibular nerve fibers in the cyst wall prevented total removal of the cyst. The histological examination confirmed the diagnosis of an arachnoid cyst.

CONCLUSION:

The endoscope-assisted microsurgical technique enables a safe cyst resection with good visualization of important neurovascular structures within the internal auditory canal. Small remnants of the capsule that are firmly attached to important neurovascular structures should be left in place rather than risk neurological deficits.

Location, sidedness, and sex distribution of intracranial arachnoid cysts in a population-based sample

Object

The aim of this study was to examine the distribution of intracranial arachnoid cysts in a large and unselected patient population with special emphasis on sidedness and sex distribution.

Methods

In total, 299 patients with 305 arachnoid cysts were studied. These patients were consecutively referred to our department during a 20-year period from a well-defined geographical area with a stable population.

Results

There was a strong predilection (198 patients [66.2%]) for intracranial arachnoid cysts in the temporal fossa. Forty-two patients had cysts overlying the frontal convexity, 36 had cysts in the posterior fossa, and 23 patients had cysts in other, different locations. Of 269 cysts with clearly unilateral distribution, 163 were located on the left side and 106 on the right side. This difference resulted from the marked preponderance of temporal fossa cysts on the left side (left-to-right ratio 2.5:1; p < 0.0001 [adjusted < 0.0005]). For cysts in the cerebellopontine angle (CPA), there was preponderance on the right side (p = 0.001 [adjusted = 0.005]). Significantly more males than females had cysts in the temporal fossa (p = 0.002 [adjusted = 0.004]), whereas in the CPA a significant female preponderance was found (p = 0.016 [adjusted = 0.032]). For all other cyst locations, there was no difference between the 2 sexes.

Conclusions

Arachnoid cysts have a strong predilection for the temporal fossa. There is a sex dependency for some intracranial locations of arachnoid cysts, with temporal cysts occurring more frequently in men, and CPA cysts found more frequently in women. Furthermore, there is a strong location-related sidedness for arachnoid cysts, independent of patient sex. These findings and reports from the literature suggest a possible genetic component in the development of some arachnoid cysts.

Neuropsychological features of lesion-related epilepsy in adults: an overview

Lesional epilepsy is thought to be a direct consequence of focal brain lesions of dysgenetic, neoplastic, vascular, or traumatic origin. It has been estimated that at least half of all epilepsies are the result of such lesions. The current discussion includes an overview of the cognitive and behavioral presentations in adults with epilepsy secondary to focal pathology. The neuropsychological presentation in this population is influenced by many factors, including the location and nature of the underlying lesion, seizure characteristics, the effects of treatment, and patient variables. Few studies attempt to disentangle the specific contributions of these variables to cognitive performance. However, where available studies examining the separable effects of seizure-related variables on cognitive functioning in individuals with lesional epilepsy are also reviewed. This overview includes a discussion of focal malformations of cortical and vascular development and select foreign tissue and acquired lesions.

ECT in patients with arachnoid cysts

Electroconvulsive therapy (ECT) is often considered relatively contraindicated in patients with intracranial space-occupying lesions, especially those with increased intracranial pressure, edema, or mass effect. We describe the safe use of ECT in 6 patients with arachnoid cysts. We conclude that such lesions are probably not associated with increased morbidity in ECT but that neurological evaluation pretreatment is indicated.

Arachnoid cysts: spontaneous resolution distinct from traumatic rupture. Case report

Although many arachnoid cysts are discovered incidentally and require no intervention, a small subset has been known to rupture. Note that rupture can occur either spontaneously or in association with trauma. Based on a review of the literature on ruptured arachnoid cysts, it appears that patients with middle fossa cysts are more likely to experience symptomatic traumatic rupture than those with cysts in other locations. Middle fossa cysts are more commonly associated with hemispheric subdural collections and hematomas than are any other cysts. The authors report on two representative cases illustrating the distinct presentation, imaging characteristics, and management of these cysts.

Huge arachnoid cyst incorporating choroid plexus

BACKGROUND

We report a rare case of arachnoid cyst incorporating choroid plexus. This 7-month-old girl presented with macrocrania. Magnetic resonance (MR) imaging disclosed a cystic lesion arising from the left prepontine cistern extending to the left middle cranial fossa.

METHODS

First, we performed resection of the membrane microscopically and obtained an adequate reduction of the cystic size. However, 4 months after the first operation, the cyst was enlarged again, and bulging of the portion of the craniotomy was noted. Thus, we performed neuroendoscopic transcortical ventriculo-cyst-cysternostomy and confirmed the choroid plexus inside of the arachnoid cyst.

DISCUSSION

Postoperative course was uneventful. This is the first reported case of choroid plexus within an arachnoid cyst, determined neuroendoscopically.

Obstructive hydrocephalus associated with arachnoid cyst in the elderly

We present a case of a symptomatic frontal arachnoid cyst associated with hydrocephalus in an elderly patient. It is well known that symptomatic arachnoid cysts usually develop at an early age. This condition is rarely observed in the elderly. The authors hypothesized that compression of the brain and obstructive hydrocephalus caused the arachnoid cyst to become symptomatic.

[Multiseptated arachnoid cyst treated with fenestration after valvular insufficiency in an adult. ]

Treatment of symptomatic arachnoid cysts is based on two procedures: cyst fenestration versus derivation of CSF. Multiseptated cysts represent a very special group. We present the case of a 75 year old woman with a symptomatic multiseptated arachnoid cyst, developing subacute bleeding in one of the cavities. Final diagnosis was obtained after MRI. CSF derivation became insufficient with clear improvement after fenestration and communication to subarachnoid space.

Interhemispheric arachnoid cyst in the elderly: case report and review of the literature

BACKGROUND

Preoperative differential diagnosis of interhemispheric cysts is sometimes difficult.

CASE DESCRIPTION

We recently experienced a case of symptomatic interhemispheric arachnoid cyst in a 62-year-old woman. We reviewed interhemispheric arachnoid cysts in the elderly and the management of symptomatic interhemispheric arachnoid cysts in elderly patients. Symptomatic interhemispheric arachnoid cysts in the elderly are predominantly located on the right side, have a long history of progressive symptomology, occur predominantly in females, and have no communication with the subarachnoid space. Interhemispheric arachnoid cysts are usually not associated with agenesis of the corpus callosum in elderly patients, whereas interhemispheric nonarachnoid cysts are usually associated with agenesis of the corpus callosum, which will be clearly demonstrated on magnetic resonance imaging.

CONCLUSIONS

It is highly possible that an interhemispheric cyst without agenesis of the corpus callosum in an adult is an arachnoid cyst.

Intracranial intra-arachnoid cyst with intracystic hemorrhage in two dogs

Clinical signs, magnetic resonance imaging (MRI) features, treatment, and outcome of two adult dogs with neurologic dysfunction resulting from hemorrhage into a quadrigeminal intracranial intra-arachnoid cyst are described. In dog 1, the cyst was hyperintense to cerebrospinal fluid (CSF) on T1-weighted MRI and hypointense to CSF on T2-weighted images. In dog 2, the cyst was isointense to CSF on T1- and T2-weighted images. Both dogs were treated with craniotomy and cyst fenestration. A large blood clot was removed from the lumen of the cyst in each dog. Dog 1 is clinically normal 3.5 years post-surgery and has a persistent cyst. Dog 2 had a good initial response to therapy but was euthanized 2.5 years post-operatively due to generalized seizures. The late onset of clinical signs in these dogs most likely resulted from hemorrhage into the cyst. Surgical fenestration and hematoma removal appear to provide a satisfactory treatment for adult dogs with an intracranial intra-arachnoid cyst and intracystic hemorrhage. Persistence of the cyst may occur in some dogs.

Arachnoid cyst: adversity and plasticity

We report four cases of surgically treated intracranial arachnoid cysts, one with cyst-peritoneal shunt and three with craniotomy and arachnoid membrane resection. Their classification and etiopathogeny are discussed, and especially the different methods of treatment comparing the drastic complications (adversities) with the favorable solutions in severe clinical cases (plasticity) treated at our institution.

Arachnoid cysts of the posterior fossa

BACKGROUND

The surgical indications and management of posterior fossa arachnoid cysts (AC) are still controversial. Different surgical techniques and management have already been suggested for arachnoid cysts of the posterior fossa. AC involving the posterior fossa and especially the cerebellopontine angle may carry a high surgical morbidity because of the involvement of important neurovascular structures (e.g., brain stem and cranial nerves). Only long-term follow-up will determine the best surgical technique for such lesions.

METHODS

Between 1990 and 1996 a total of 12 patients underwent surgery for arachnoid cysts involving the posterior fossa. In seven cases AC were located within the cerebellopontine angle (CPA), in three cases in the CPA with major extension dorsal to the brainstem, and in two cases at the CPA extending into the internal auditory canal.

RESULTS

A suboccipital retrosigmoid approach was performed in all patients. Radical resection of the cyst could be accomplished in all but one case. There was no mortality. Major postoperative morbidity was present in one case because of an intraoperative air embolism in the semisitting position and strong adherence of the cyst wall to the surrounding neurovascular structures. Long-term follow-up (mean, 3.3 years) revealed improvement of most preoperative symptoms.

CONCLUSION

Open surgery and radical removal of the AC located at the posterior fossa, based on our retrospective analysis, provide very good long-term postoperative results. The suboccipital approach provides a good and safe exposure of vascular structures and cranial nerves in the CPA and allows radical resection of the cyst, reducing the chance of recurrence.

Endoscopic neurosurgery and endoscope-assisted microneurosurgery for the treatment of intracranial cysts

OBJECTIVE

Different endoscopic techniques have been introduced into neurosurgery, but accepted terminology and definitions are still missing. We propose a terminology based on whether the endoscope is used alone or in conjunction with an operating microscope and on whether the route of surgical manipulations is through or outside the endoscope. Accordingly, procedures are categorized into endoscopic neurosurgery (EN), endoscope-assisted microneurosurgery (EAM), and endoscope-controlled microneurosurgery (ECM).

METHODS

We treated 36 patients with intracranial arachnoid cysts (ACs) and intraventricular cysts endoscopically. The patients ranged in age from 4 months to 69 years (mean age, 31 yr). The follow-up period ranged from 6 to 44 months (mean follow-up duration, 14 mo). The indications were hydrocephalus in 17 patients, focal neurological deficits in 4 patients, progressive nonlocalizing symptomatology in 13 patients, and space occupation in 2 asymptomatic patients. EN was used in 14 cases, EAM in 15 cases, and ECM in 7 cases.

RESULTS

The overall success rate was 70%. Nine patients (25%) had unchanged symptomatology, and the condition of two patients (5%) deteriorated. The best success rates were achieved in patients with intraventricular cysts (89%) and posterior fossa ACs (78%). Symptomatic improvement was best achieved in patients with hydrocephalus or focal neurological deficits (81%).

CONCLUSION

Different endoscopic techniques (i.e., EN, EAM, and ECM) provide sufficient treatment of selected intracranial cysts. Our data suggest that intraventricular cysts and suprasellar ACs should be approached using EN whereas posterior fossa and sylvian ACs may be more effectively treated using a combined technique (EAM or ECM).

Arachnoid cysts: how do postsurgical cyst size and seizure outcome correlate?

Arachnoid cysts (ACs) are congenital cystic brain malformations associated with epilepsy. The purpose of this study was to determine the effect of surgical intervention of ACs on cyst size and seizure outcome. We reviewed the world's medical literature dealing with surgically treated ACs in epilepsy patients. Our study included only cases, in which the relationship between pre-and postoperative CT-size of the AC and seizure outcome was described. We also included six patients with ACs and epilepsy treated surgically at the University of Mainz. We analyzed postoperative AC size and seizure outcome with respect to mode of operation, cyst location, and patients' age. A total of 76 patients was reviewed. Sixty (79%) patients had a smaller AC postoperatively. Forty-six of those 60 (76.6%) experienced seizure improvement. Thirteen patients (21.6%) remained unchanged and one patient (1.8%) worsened. In 16 of the 76 patients (21%) the postoperative AC size was unchanged. Eight of those 16 patients improved. Six patients (37.5%) remained unchanged and two (12.5%) worsened. A positive correlation between postoperative AC size and seizure outcome was well demonstrated among patients treated by cyst fenestration, needle aspiration, or internal shunting. Among patients treated by cystoperitoneal shunting this direct correlation was less clear. Seizure outcome correlates directly with postoperative AC size. Seizure reduction is associated with decreased AC size postoperatively and depends on the mode of operation. Based on these data we would expect that patients with epilepsy secondary to ACs would demonstrate improved seizure control with lower AC volume. Conversely, we might expect increasing AC size to correlate with worse seizure control. This relationship may guide physicians in efficacy and timely patient management.

Magnetic resonance imaging and computed tomography characteristics of intracranial intra-arachnoid cysts in 6 dogs

Magnetic resonance imaging (MRI) and computed tomographic imaging (CT) characteristics of intracranial intra-arachnoid cysts in six dogs are described. Of the six dogs, three were less than one year of age and 4 were males. Five of the six dogs weighed less than 11 kg. Five cysts were located in the quadrigeminal cistern. On CT images, the intracranial intra-arachnoid cysts had sharply defined margins, contained fluid isodense to CSF and did not enhance following i.v. administration of contrast. On MRI images, the intracranial intra-arachnoid cysts were extra-axial, contained fluid isointense with CSF and did not enhance following i.v. contrast. While spinal arachnoid cysts of dogs have been reported in the literature, other than the six dogs contained in this report, intracranial intra-arachnoid cysts have not to our knowledge been described in animals. These six dogs have a similar age, sex, history, clinical signs, CT and MRI findings to those reported in people with intracranial intra-arachnoid cysts.

Arachnoid cysts associated with subdural hematomas and hygromas: analysis of 16 cases, long-term follow-up, and review of the literature

OBJECTIVE

Subdural hematomas and hygromas are infrequently encountered complications of arachnoid cysts of the middle cranial fossa and are particularly rare with cysts of other regions. Reports in the literature focus on casuistic observations. Therapeutic recommendations often include fenestration or extirpation of the cyst wall, in addition to evacuation of the space-occupying lesion. This study evaluates the results of and rationale for a more conservative approach, usually without cyst removal.

METHODS

Sixteen cases of complicated arachnoid cysts, from a total of 658 patients with subdural hematomas or hygromas, were analyzed retrospectively together with 75 other cases reported in the literature. Additionally, 94 magnetic resonance imaging scans from 89 patients with untreated arachnoid cysts, from a total of 11,487 examinations, were reviewed for signs of hemorrhagic complications.

RESULTS

Arachnoid cysts of the middle cranial fossa were found in 2.43% of patients with chronic subdural hematomas or hygromas. This indicated a fivefold greater prevalence of arachnoid cysts, compared with our magnetic resonance imaging-examined patient group. Only two patients with untreated cysts showed signs of hemorrhage in magnetic resonance imaging scans. An excellent or good therapeutic result was achieved with evacuation of the subdural fluid by drainage or craniotomy in 13 cases and with conservative treatment in two cases. Only one patient underwent additional fenestration of the cyst wall. No additional symptoms from the arachnoid cysts occurred in a follow-up period of up to 14 years after therapy.

CONCLUSIONS

We do not generally consider it necessary to perform cyst diversion or fenestration at the time of drainage of a hematoma or hygroma in previously asymptomatic arachnoid cysts.

Neuroendoscopic approach to arachnoid cysts

A prospective study of seven consecutive patients with congenital arachnoid cysts treated endoscopically is reported. The ages of the patients at the time of diagnosis ranged from 6 to 47 years with three patients under 15 years. Two cysts were located in the posterior cranial fossa, four in the middle cranial fossa, and one in the suprasellar-prepontine area. The patients' symptoms included headache, seizures, vomiting, nausea, dizziness, balance problems, and precocious puberty. The authors performed cystocisternostomies and ventriculocystostomies via burr holes with the aid of a universal neuroendoscopic system. Minor bleeding was easily controlled by rinsing. In one case, the endoscopic procedure had to be abandoned because of significant bleeding, which obscured a clear operative view, and an open microsurgical cyst fenestration was performed. The follow-up review periods in this group of patients ranged from 15 to 30 months. There was no mortality or morbidity. Symptoms were relieved in five patients and improved in one. Precocious puberty in one case continued. In six cases, follow-up magnetic resonance images or computerized tomography scans revealed a decrease in the size of the cysts. Although the follow-up period is too short to make statements on long-term outcome, the authors recommend the minimally invasive endoscopic approach for treatment of arachnoid cysts as the first therapy of choice. Should the endoscopic procedure fail, established treatment options such as microsurgical fenestration or cystoperitoneal shunting can subsequently be performed without causing additional risk to the patient.

[Brainstem hemorrhage after surgical removal of arachnoid cyst of the Sylvian fissure: a case report]

The authors report a case of a hemorrhage of the brainstem after craniotomy for resection of a huge arachnoid cyst of the sylvian fissure on the left hemisphere. The previous simptomatology included clinical signs of increased intracranial pressure, and the computerized tomography showed midline shift. Some factors may contribute to brain hemorrhage post-operatively: cerebral edema, ipsilateral changes in the venous reflux and blood perfusion, although the physiopathology remains obscure. A more careful approach is suggested in such cases with intracranial hypertension.

Disappearance of arachnoid cysts after head injury

The mechanism of the disappearance of arachnoid cysts is not fully understood. This article discusses the spontaneous disappearance of these cysts after head injury. Five patients underwent computed tomography and were diagnosed as having a subdural hematoma or effusion associated with arachnoid cysts. In four of the five patients, the cyst decreased in size or disappeared. These cases suggest a possible mechanism by which this type of cyst associated with subdural hematoma or effusion might disappear. For the arachnoid cyst to disappear, the rupture of the cyst wall appears to be essential, and after rupture, subdural effusion must develop around the cyst. As this effusion is absorbed, the fluid in the cyst drains away, after which the cyst becomes smaller and gradually disappears. This hypothesis supports the possibility of a "natural cure" for arachnoid cysts without surgical intervention.

Supratentorial arachnoid cysts: clinical and therapeutic remarks on 46 cases

The authors report 46 cases of primary supratentorial arachnoid cysts. Thirty-two patients presented with symptomatic arachnoid cysts, which act as space-occupying lesions and were surgically treated by fenestration. 14 patients presented with a scarcity of symptoms; for this reason they were kept under control by periodical neuroradiological examination. After a long follow-up period (median 11 years), 97% of the operated patients presented neurological improvement and a decrease in the size of the cyst; none of the patients who were not operated on showed any variation in either neurological status or size of the cyst. The authors discuss their findings in the light of the published papers.

Two cases of symptomatic interhemispheric arachnoid cyst in the elderly

We recently experienced two cases of symptomatic interhemispheric arachnoid cyst (IHAC) in the elderly, both extending into the frontoparietal region. Both patients presented with more than an 8-year history of progressive hemiparesis and underwent capsule resection in combination with internal drainage to the pericallosal cistern via the interhemispheric approach. Postoperatively, the cyst cavities were greatly reduced in size, and neurologic signs and symptoms were markedly improved. A discussion of the diagnosis, mechanism of symptom onset, and management of symptomatic IHAC in the elderly is presented.

Symptomatic, expansive middle cranial fossa arachnoid cyst treated by a cysto-peritoneal shunt. Case report and evaluation of treatment options

We report a symptomatic space-occupying arachnoid cyst in a 16-year-old boy. During the last two years, he was frequently absent from school because of headaches. Due to symptoms of nausea, fever and headache the patient was primarily referred to a surgical unit, where appendectomy was performed, revealing a normal appendix. Postoperatively, the patient complained of severe headache. Computed tomography (CT) of the head demonstrated a large left-sided middle cranial fossa arachnoid cyst. The patient was operated with insertion of a cysto-peritoneal shunt. A total regress of the clinical symptoms was seen at follow-up examination 3 months after shunting.

Primary intracranial arachnoid cyst in the elderly

Sixteen cases of symptomatic arachnoid cyst in elderly patients (> 65 years of age) including of our own case are considered and their clinical and therapeutic features compared with those of the larger series comprising younger patients. From this study, no clinical differences emerged between arachnoid cysts in elderly patients and those of their younger counterparts. Surgical treatment was confirmed as being necessary for a good outcome in this age group when the cysts became symptomatic.