Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FENESTRATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed2004

Pathogenetic significance of myxomatous degeneration in fenestration-related massive aortic regurgitation.

BACKGROUND: Aortic valvular regurgitation has several mechanisms and the present study investigated its clinicopathological correlations with aortic valve fenestration. METHODS AND RESULTS: Six male patients with massive regurgitation and enlarged fenestrations or ruptured fenestrated fibrous cords underwent aortic valve replacement. The clinicopathological features showed many similarities. Four cases had family histories of aortic regurgitation. All six patients showed moderate to severe myxomatous degeneration of the aortic valve and enlargement of aortic annulus. Four patients had 1-2 ruptured fibrous cords, located at the right coronary cusp. Echocardiographic examinations showed an abnormal fibrous cord attached to the prolapsing cusp in 3 cases with ruptured fenestrated valve and detailed examination by transesophageal echocardiography showed an intact fenestrated fibrous cord at the commissure in 1 case. CONCLUSION: Extensively fenestrated cusps with an enlarged aortic annulus because of myxomatous degeneration can cause chronic regurgitation or sudden deterioration after rupture of the fibrous cord. There is an increasing incidence of fenestration-related aortic regurgitation in the Japanese population. An important pathogenetic factor in male patients is myxomatous degeneration of the aortic cusp and annulus.

Adult↗
PubMed2006

Outcomes of fenestrated endografts in the treatment of abdominal aortic aneurysm in Western Australia (1997-2004).

PURPOSE: To describe a 7-year experience with abdominal aortic aneurysm (AAA) repair using fenestrated Zenith endovascular endografts. METHODS: Six endovascular surgeons from 7 medical centers in Perth, Western Australia, contributed data to this retrospective study of 58 AAA patients (51 men; mean age 75.5+/-8.5 years, range 60-94) treated with fenestrated endografts. Fenestrations were applied to 116 target vessels; more than half of patients had >/=2 target vessels. The results were based on satisfactory deployment of the stent-graft and fenestrations (technical success), technical success and no complications (procedural success), and aneurysm exclusion with no endoleak, rupture, unresolved complications, or dialysis (treatment success). RESULTS: Technical success was 82.8% for patients (90.5% for target vessels), procedural success was 74.1%, and treatment success was 94.8%. There were no cases of conversion or rupture. The 30-day mortality rate was 3.4% (n=2). Over a mean follow-up of 1.4+/-1.2 years, 10 (17.2%) patients experienced loss of a target vessel (9.5% of target vessels). Factors associated with target vessel loss were no stent, >60 degrees neck angulation, multiple renal vessels, and vessel diameter </=4 mm. Four (6.9%) patients developed renal impairment, but none required dialysis. Fourteen (24.1%) patients had a secondary intervention. Unresolved endoleaks persisted in 1 (1.7%) patient. CONCLUSION: Fenestrated endografts extend the treatment options for infrarenal AAAs with necks unsuitable for standard endovascular repair. This early data show a trend toward higher mortality of selected patients with fenestrated endografts than for standard stent-graft repair, but the mortality rate is comparable to open repair. Target vessel occlusion predominantly results from pre-existing disease or the lack of a stent. The lessons learned from this experience contributed toward guidelines for users of fenestrated endografts.

Aged↗
PubMed2002

Microsurgical fenestration of the lamina terminalis reduces the incidence of shunt-dependent hydrocephalus after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Hydrocephalus requiring shunt placement is a common complication after aneurysmal subarachnoid hemorrhage (aSAH). Previous investigations suggest that fenestration of the lamina terminalis during microsurgery for aSAH may be associated with a reduced rate of shunt-dependent hydrocephalus. We report a retrospective analysis correlating fenestration of the lamina terminalis with decreased shunt-dependent hydrocephalus after aSAH. METHODS: During the past decade, 582 patients were admitted to our institution with aSAH. We compared the rate of shunting in patients operated on by a neurosurgeon ("index neurosurgeon") who routinely fenestrated the lamina terminalis (>98% of his patients) with that in patients managed by 14 other neurosurgeons who rarely fenestrated the lamina terminalis (<5% of their patients) and by 6 interventional neuroradiologists. The total cohort was subdivided into two groups on the basis of surgical approach and microsurgical access to the lamina terminalis. Group A included frontosphenotemporal craniotomies, an approach in which the lamina terminalis is accessible, and Group B included other approaches in which the lamina terminalis is not accessible. Shunting rates of the index neurosurgeon and those of the other practitioners were compared within Groups A and B. Shunting rates were compared by logistic regression and multivariable analysis. This study design isolates the effect of fenestrating the lamina terminalis on the incidence of shunt-dependent hydrocephalus. RESULTS: In Group A, the index neurosurgeon had a significantly lower rate of shunting, 2.3%, versus 12.6% for other practitioners (P = 0.011; odds ratio, 0.15). In Group B, in which the approach did not allow microsurgical fenestration of the lamina terminalis, there was no difference (P = 0.789) in the rate of shunting between the index neurosurgeon (10.0%) and other practitioners (13.2%). CONCLUSION: Fenestration of the lamina terminalis appears to be associated with a decreased incidence of shunt-dependent hydrocephalus of more than 80% after aSAH. This straightforward microsurgical maneuver should be performed whenever possible during aneurysm surgery.

Acute Disease↗
PubMed2005

Fenestrated and branched endovascular techniques for thoraco-abdominal aneurysm repair.

Since 1991, endovascular aortic aneurysm repair (EVAR) has been established as an alternative for open surgical repair of aortic aneurysms. One of the main limitations for EVAR is the need for a sufficient sealing zone below or above vital aortic side branches. Recently, efforts have been made to overcome these limitations by incorporating fenestrations or branches in customized stent-grafts. This paper reviews the technical and clinical possibilities, as well as the results with fenestrated and branched stent-grafts. All these techniques can be classified into 6 groups, including abdominal fenestrated, abdominal branched, thoraco-abdominal fenestrated, thoraco-abdominal branched, thoracic fenestrated, and thoracic branched stent-grafting. The only well-elaborated technique at this moment is abdominal fenestrated stent-grafting. Currently, branched stent-grafting must be regarded as experimental, but advancements are taking place rapidly. It is anticipated that wider adoption will take place in the near future. New developments include the further use of reinforced fenestrations, indwelling catheters and flexor sheaths, as well as the use of new type branches.

Aortic Aneurysm, Abdominal↗
PubMed1992

Fenestrated Fontan operation with delayed transcatheter closure of atrial septal defect. Improved results in high-risk patients.

Ten patients, each with two or more risk factors for morbidity and death, underwent a fenestrated Fontan procedure in which a 4 to 6 mm circular fenestration was left between the systemic and pulmonary venous chambers. None died; a similar group of high-risk patients without fenestration had a mortality rate of 2 of 8. Patients with fenestration had significantly less drainage from the chest tube, less need for inotropic support, and shorter intensive care and hospital stays than did patients without fenestration. Comparison with a group of low-risk patients undergoing the Fontan operation showed no statistical difference in these postoperative parameters. Fenestrations were closed in all 10 patients at from 9 days to 6 months after operation by means of the transcatheter clamshell occluder device. Two patients had left pulmonary artery balloon angioplasty and three patients had other atrial communications closed with additional clamshell devices. During short-term follow-up periods averaging 18 months, all patients were clinically well; however, one patient with mitral atresia required reoperation for obstruction between the left atrium and the tricuspid valve, not related to the clamshell device. These data indicate that fenestration may be one method of achieving lower morbidity and mortality rates among high-risk patients undergoing the Fontan procedure.

Adolescent↗
PubMed1990

[Fenestrated basilar artery with ruptured cerebral aneurysms: case report].

Two cases of aneurysms with basilar artery fenestration are presented. A 45 year-old lady had a saccular aneurysm associated with a fenestrated basilar artery. The fenestration was located in the proximal third of the basilar artery. The aneurysm arose from the proximal end of the fenestration, projecting antero-inferiorly. Via a left retromastoid craniectomy, the aneurysm was successfully obliterated through the space between the eighth cranial nerve and the lower cranial nerve complexes. Postoperative deficit in the lower cranial nerves was minimal and transient. The other patient, a 63 year-old lady, had multiple aneurysms arising from the anterior circulation associated with a basilar artery fenestration. These aneurysms were clipped uneventfully. Surgical approach to an aneurysm arising from the basilar artery fenestration is discussed with other related literature. Full study of posterior circulation with multiple projection is mandatory to detect basilar artery fenestration, and the possible presence of saccular aneurysm at the site of the anomaly.

Basilar Artery↗
PubMed1988

[Accessory nerve paralysis due to compression of the fenestrated vertebral artery].

Neurological involvement due to fenestrated vertebral artery has not yet been reported, although fenestration formation by vertebral arteries is not rare. Reported here is one such rare case. In this case accessory nerve paralysis developed due to fenestrated vertebral artery. A 51-year-old woman was admitted to our department with tilting of the head to the right side as her chief complaint. This had gradually developed over a period of approximately one year. Neurological examination on admission showed the presence of marked atrophy of the left sternocleidomastoid muscle with hyperactive deep tendon reflexes in her four limbs. Metrizamide CT scan showed compression of the upper cervical cord at the left side, and an abnormal small high density area was found at the same site on contrast enhanced CT scan. Left vertebral angiogram showed fenestration formation of the left vertebral artery at C1 level. Surgical decompression for the left accessory nerve and high spinal cord was planned because of the occurrence of symptoms due to compression of the fenestrated vertebral artery. C1 and C2 laminectomy was performed and the dura was opened in prone position. The fenestrated vertebral artery of the intraspinal portion was confirmed to be compressing the spinal root of the accessory nerve and high cervical cord. Initially, trapping of the fenestrated vertebral artery was attempted in the hope of sufficiently relieving compression on the accessory nerve and high cervical cord. This attempt resulted in failure, since auditory evoked response became definitely abnormal within two minutes following interruption of this abnormal artery. Because of this, insertion of Ivaron sponges between the abnormal artery and the accessory nerve was all that could be done.(ABSTRACT TRUNCATED AT 250 WORDS)

Accessory Nerve↗
PubMed2002

The effect of noise exposure in the presence of canal fenestration on the amplitude of short-latency vestibular evoked potentials.

BACKGROUND: Exposure to high-intensity noise causes little, if any, reduction in vestibular function in normal animals as shown by short-latency vestibular evoked potentials (VsEPs). OBJECTIVE: To investigate the effect of noise exposure on VsEPs following fenestration of the horizontal semicircular canal. DESIGN AND METHODS: Psammomys obesus (fat sand rat) underwent labyrinthectomy in 1 ear, while the lateral semicircular canal in the other ear was fenestrated. Control VsEPs to linear acceleration (approximately 3g; rise time, approximately 1-2 milliseconds) were recorded immediately after the operation. The experimental group animals were then subjected to loud white noise (113-dB sound pressure level) for 1 hour. Immediately after the noise exposure in the experimental group animals, VsEPs were once more recorded. RESULTS: The VsEPs in the experimental group animals were significantly reduced immediately following the noise exposure, while there was no change in the recordings from the control group animals (fenestrated but not noise exposed; noise exposed but not fenestrated), even though the noise exposure induced a mean 47-dB threshold elevation of the auditory brainstem response. CONCLUSIONS: The presence of the fenestration caused the vestibular end organs to become vulnerable to noise exposure. The fenestration may create a pathway enabling pressure release through the vestibular end organs during noise exposure, thus increasing the possibility of damage to the vestibular end organs. This did not occur in the intact, nonfenestrated animals.

Analysis of Variance↗
PubMedDate not supplied

Laser fenestration of the mesial septum for treatment of guttural pouch chondroids in a pony.

OBJECTIVE: To describe removal of guttural pouch chondroids through a laser fenestrated mesial septum in a pony with an obstructed pharyngeal ostium of the left guttural pouch. STUDY DESIGN: Case report. ANIMALS: Pony. METHODS: Transendoscopic laser neodymium:yttrium aluminum garnet (Nd:YAG) fenestration of the mesial guttural pouch septum was made by contact method (bare fiber, 15-25 W, exposure time 4 seconds). Dissected tissue was removed by transendoscopic monopolar electrosurgery (loop electrode, cutting blade) and multiple chondroids of varying size were removed from the left guttural pouch through the fenestration. RESULTS: After removing all chondroids and repeated flushing of the left guttural pouch via the right side, inflammation of the guttural pouch membranes decreased remarkably. The pony was discharged with instructions for transendoscopic lavage once weekly and was reevaluated at 2 months. A permanent septal fenestration was observed and the pony was free of abnormal clinical signs and being used for carriage driving competitions. CONCLUSION: Nd:YAG laser fenestration of the mesial septum is an approach for access to guttural pouch chondroids. CLINICAL RELEVANCE: When guttural pouch empyema and/or chondroids is associated with adhesion of the pharyngeal ostium, laser fenestration of the mesial septum from the opposite guttural pouch should be considered as an alternative approach for access, rather than classic external surgical approaches.

Animals↗
PubMed1985

Fenestration of the horizontal semicircular canal in congenital conductive deafness.

Fenestration of the horizontal semicircular canal enables the otologic surgeon to restore hearing in those patients with congenital conductive deafness who are not candidates for stapedectomy, ossicular reconstruction, or tympanoplasty. Since the development of stapedectomy, much of the finesse technique of fenestration surgery has been lost, and many otologic surgeons today are unfamiliar with the fenestration operation. The surgical technique for creating a permanently patent fenestra in the horizontal semicircular canal is described. The causes of failure in fenestration surgery are reviewed. Thirty-three patients who have undergone fenestration for congenital conductive deafness over a 30-year period, and 100 patients who underwent fenestration for otosclerosis in 1950, are reviewed to demonstrate patient selection and the efficacy of this operation in establishing long-term hearing improvement.

Adolescent↗
PubMed2001

Device closure of fenestrated atrial septal defects: use of a single Amplatz atrial septal occluder after balloon atrial septostomy to create a single defect.

Successful transcatheter device closure of secundum atrial septal defect has achieved worldwide acceptance with the clinical use of the Amplatz atrial septal occluder. However, device closure of multiple fenestrated secundum atrial septal defects remains a challenge for the interventionist and in some cases may be only effectively closed surgically. This case report of multiple fenestrated atrial septal defects represents a further expansion of technologic efforts to improve the results and simplify the mechanism of device closure of fenestrated defects. When device closure with more than one device seems impractical or disadvantageous, consolidation of multiple defects in a fenestrated fossa ovalis by simple balloon atrial septostomy as demonstrated by this case report provides an easy mechanism to allow implantation of a single large device which will effectively close all of the defects. This approach is similar to the surgical approach for resection of the fenestrated membrane with secondary patch closure of the enlarged defect. Excellent and complete closure of a fenestrated secundum atrial septal defect is illustrated in this case report.

Balloon Occlusion↗
PubMed2003

Chronic and acute analysis of optic nerve sheath fenestration with the free electron laser in monkeys.

BACKGROUND AND OBJECTIVES: The Amide II wavelength (6.45 microm) produced by the free electron laser (FEL) can efficiently create an optic nerve sheath fenestration in rabbits. We wished to determine if it would be equally successful in macaque monkeys and to determine the histopathologic changes between traditional scissors or knife optic nerve sheath fenestration to FEL fenestration. STUDY DESIGN/MATERIALS AND METHODS: Optic nerve sheath fenestration was performed using either the FEL (6.45 microm, 30 Hz, 2-3 mJ, 325-microm spot size) through a hollow waveguide probe in 12 eyes or with a scissors or a knife in 6 eyes. The monkeys survived 1 month with the fellow optic nerve operated acutely just prior to sacrifice. Optic nerves were evaluated histologically. RESULTS: Less tissue manipulation was required using the FEL surgical probe. Electroretinograms showed minimal or no change. Tissue responses using either method were similar following chronic or acute incisions. Mild upregulation of vimentin and glial fibrillary acid protein (GFAP) was seen in astrocytes adjacent to the fenestration, but no change in S100 beta was evident. CONCLUSIONS: The FEL energy at 6.45 microm delivered through a hollow waveguide appears capable of efficiently and safely producing an optic nerve sheath fenestration in monkeys. This innovative surgical technique should be considered for human use.

Animals↗
PubMed1997

The fine structure of fenestrated adrenocortical capillaries revealed by in-lens field-emission scanning electron microscopy and scanning transmission electron microscopy.

Cell biologists probing the physiologic movement of macromolecules and solutes across the fenestrated microvascular endothelial cell have used electron microscopy to locate the postulated pore within the fenestrae. Prior to the advent of in-lens field-emission high-resolution scanning electron microscopy (HRSEM) and ultrathin metal coating technology, quick-freeze, platinum-carbon replica and grazing thin-section transmission electron microscopy (TEM) methods provided two-dimensional or indirect imaging methods. Wedge-shaped octagonal channels composed of fibrils interwoven in a central mesh were depicted as the filtering structures of fenestral diaphragms in images of platinum replicas enhanced by photographic augmentation. However, image accuracy was limited to replication of the cell surface. Subsequent to this, HRSEM technology was developed and provided a high-fidelity, three-dimensional topographic image of the fenestral surface directly from a fixed and dried bulk adrenal specimen coated with a 1 nm chromium film. First described from TEM replicas, the "flower-like" structure comprising the fenestral pores was readily visualized by HRSEM. High-resolution images contained particulate ectodomains on the lumenal surface of the endothelial cell membrane. Particles arranged in a rough octagonal shape formed the fenestral rim. Digital acquisition of analog photographic recordings revealed a filamentous meshwork in the diaphragm, thus confirming and extending observations from replica and grazing section TEM preparations. Endothelial cell pockets, first described in murine renal peritubular capillaries, were observed in rhesus and rabbit adrenocortical capillaries. This report features recent observations of fenestral diaphragms and endothelial pockets fitted with multiple diaphragms utilizing a Schottky field-emission electron microscope. In-lens staging of bulk and thin section specimens allowed tandem imaging in HRSEM and scanning TEM modes at 25 kV.

Adrenal Cortex↗
PubMed1996

Capillaries in the lamina propria of human seminiferous tubules are partly fenestrated.

The three capillary parts of the microvasculature of the human testis, namely the arterial side inter-Leydig cell capillaries, the intramural capillaries, and the venous side inter-Leydig cell capillaries, were studied in detail by dual detection of alkaline phosphatase enzyme activity and endothelial marker immunoreactivity, and by means of light- and transmission-electron microscopy. Alkaline phosphatase enzyme activity was seen in intertubular arterioles, capillaries, and venules, and in intramural capillaries of the human testis, whereas the lamina propria of human seminiferous tubules showed no staining. Alkaline phosphatase enzyme activity and the endothelial marker detected by the Qbend 30 antibody co-existed within the endothelial cells of the microvasculature. Electron-microscopically, the endothelial cells of the arterial and venous side inter-Leydig cell capillaries, and of the intertubular capillaries free of Leydig cells were of the continuous type without fenestrations (A-1-alpha type). The intramural capillaries consisted of non-fenestrated (A-1-alpha type) and fenestrated sections (A-2-alpha type). The fenestrations faced the germinal epithelium. Capillaries with a continuous non-fenestrated endothelium contained a large number of transcytotic vesicles and channels. These were numerous in the endothelial cells of the inter-Leydig cell capillaries and the non-fenestrated part of the intramural capillaries. Capillaries partly ran in between the layers of the lamina propria and therefore represented the capillarization of the seminiferous tubules. Thus the multilayered lamina propria probably requires its own capillary supply to allow rapid exchange between the microvasculature and the epithelium of the human seminiferous tubules.

Arterioles↗
PubMed1993

Obligatory Glenn shunt in fenestrated Fontan.

Five high-risk patients undergoing the Fontan operation required large fenestration (1 cm) because of high central venous pressure and low cardiac output. Because of major arterial desaturation, obligatory Glenn shunts were performed. Three patients had pulmonary atresia, 1 had tricuspid atresia 1-B, and the fifth had single ventricle with subaortic stenosis. The age ranged from 16 to 40 months (mean age, 25 +/- 9 months) and weight from 7.9 to 14.6 kg (mean weight, 11 +/- 2 kg). One patient had single and 3 had bilateral subclavian pulmonary artery shunts. The fifth patient had pulmonary artery banding and coarctation repair followed by an aortopulmonary window and central shunt. The first 2 patients repeatedly had to go back on cardiopulmonary bypass for a larger fenestration and subsequently had an obligatory Glenn shunt because of arterial desaturation. The last 3 patients had planned obligatory Glenn shunt and large fenestration. The first patient died on the second postoperative day of a combination of prolonged operation, repeated cardiopulmonary bypass, and periods of hemodynamic instability. Three patients had closure of the adjustable fenestration under local anesthesia at 4, 5, and 8 weeks postoperatively. The last patient is awaiting closure. We believe that in certain high-risk patients, a large fenestration combined with an obligatory Glenn shunt should be considered to minimize repeated cardiopulmonary bypass and urgent tightening or closure of fenestration in the immediate postoperative period.

Arteriovenous Shunt, Surgical↗
PubMedDate not supplied

Bone augmentation at fenestrated implants by an osteopromotive membrane technique. A controlled clinical study.

Lack of bone in localized areas of the jaws frequently poses a problem when placing oral implants. In this clinical study, we have tested an osteopromotive membrane technique for its ability to create bone over buccal fenestrations after fixture installation in the maxilla. 7 patients were selected by the use of CT-scan. Criteria for patient selection were that the alveolar crest should have a vertical height >13 mm and a facial-palatal concavity, where exposure at the central portion of the fixture could be anticipated. One fenestration, randomly chosen, in each patient was covered with an e-PTFE (expanded polytetrafluoroethylene) (Gore-Tex GTAM) membrane. Contralateral fenestrations served as controls (without the placement of a membrane). The amount of newly formed bone was calculated by photometric assessments. The results showed that the fixture fenestrations, treated with the membrane technique, demonstrated a significantly (p<0.005) higher amount of new bone formation compared to the controls, where little or no improvement had taken place at the fenestrations. The study conclusively shows that the membrane technique is a reconstructive technique, able to create new bone at localized bone fenestrations at titanium fixtures. Additionally, the study also demonstrates that the periosteum alone, in adult humans, is not capable of generating new bone at exposed titanium implants.

Adult↗
PubMed2002

Endoscopic fenestration of symptomatic septum pellucidum cysts: three case reports with discussion on the approaches and technique.

OBJECTIVES: We describe three patients with symptomatic septum pellucidum cysts treated by endoscopic fenestration and discuss the different endoscopic approaches to these cysts. CLINICAL PRESENTATION: The patients are an 8-year-old boy, a 7-year-old boy and a 21-year-old woman; this last also had a right frontal cavernous angioma and a pituitary microadenoma. All patients presented with headache, associated with vomiting in two and behavioral changes in one. In all cases magnetic resonance showed a septum pellucidum cyst. INTERVENTION: Two patients were operated upon by posterior approach through a right occipital burr hole and underwent fenestration from the right occipital horn to the cyst, with a second fenestration from the cyst to the left lateral ventricle in one. Another patient underwent microsurgical removal of a right frontal cavernoma and endoscopic cyst fenestration with both lateral ventricles through a right frontal craniotomy. Postoperatively, headache and vomiting resolved in all cases and behaviour changes improved in one. CONCLUSIONS: Endoscopic fenestration is the treatment of choice for septum pellucidum cysts, where it results in immediate relief of the mass effect of the cyst and in the remission of the associated symptoms. We suggest a posterior approach through a right occipital burr hole. It allows one to easily cannulate the occipital horn, which is usually larger than the frontal one, thus avoiding the risk of damaging the vascular and neural structures surrounding the foramen of Monro. Besides, the endoscopic trajectory is in our opinion more direct. The two-window technique, with fenestration of the cyst into both lateral ventricles, improves the chances of long-term patency.

Adenoma↗
PubMed2000

Fenestration of the posteroinferior cerebellar artery: case report.

OBJECTIVE AND IMPORTANCE: Fenestrations of cerebral arteries are rare, but very important to diagnose given their high association with saccular aneurysms. We present the first reported case of a fenestration of the posteroinferior cerebellar artery (PICA). CLINICAL PRESENTATION: A 62-year-old man who presented with a subarachnoid hemorrhage underwent repeated four-vessel cerebral angiography. An isolated right PICA abnormality consistent with a dissection or fenestration was revealed. INTERVENTION: The patient underwent surgical exploration of his PICA, which confirmed a PICA fenestration without an associated saccular aneurysm. The fenestration was wrapped with cotton. CONCLUSION: Our case report illustrates the novel anatomic finding of a fenestration of the PICA. Knowledge of this entity would be helpful in the differential diagnosis of a posterior fossa subarachnoid hemorrhage.

Cerebellum↗