Midline Suboccipital Craniectomy Research Articles

Predictors of poor functional outcomes in adults with type I Chiari Malformation: Clinical and surgical factors assessed with the Chicago Chiari Outcome Scale over long-term follow-up

ObjectiveThis study aimed to identify clinical and surgical features associated with poor long-term postoperative outcomes in patients diagnosed with Type I Chiari Malformation (CMI) treated with posterior fossa decompression with duroplasty (PFDD), with or without tonsillar coagulation. MethodsThis retrospective, single-center study included 107 adult patients with CMI surgically treated between 2010 and 2021. The surgical technique involved a midline suboccipital craniectomy, C1 laminectomy, durotomy, arachnoid dissection, duroplasty, and tonsillar coagulation until 2014, after which tonsillar coagulation was discontinued. Postoperative outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS) at a median follow-up of 35 months. Clinical, surgical, and neuroimaging data were analyzed using the Wilcoxon signed-rank test, Cox regression analysis, and Kaplan-Meier survival curves to identify predictors of poor functional outcomes. ResultsOf the 107 patients (mean age 43.9 years, SD 13), 81 (75.5 %) showed functional improvement, 25 (23.4 %) remained unchanged, and 1 (0.9 %) experienced worsened outcomes. Cephalalgia, bilateral motor weakness, and bilateral paresthesia were the most frequent initial symptoms. Tonsillar coagulation was performed in 31 cases (28.9 %) but was clinically associated with higher rates of unfavorable outcomes. The Wilcoxon signed-rank test indicated that long-term follow-up CCOS was significantly higher than postoperative CCOS (Z = −7.678, p < 0.000). Multivariate Cox analysis identified preoperative bilateral motor weakness (HR 6.1, 95 % CI 1.9–18.9; p = 0.002), hydrocephalus (HR 3.01, 95 % CI 1.3–6.9; p = 0.008), and unilateral motor weakness (HR 2.99, 95 % CI 1.1–8.2; p = 0.033) as significant predictors of poor outcomes on a long-term follow-up. ConclusionThis study highlights the high rate of functional improvement in CMI patients following PFDD. Preoperative motor weakness and hydrocephalus were significant predictors of poor long-term outcomes. Tonsillar coagulation did not demonstrate a clear clinical benefit and may be associated with worse outcomes. Our findings suggest that careful preoperative assessment and selection of surgical techniques are crucial for optimizing patient outcomes.

Attempted Suicide with a Self-Inflicted Penetrating Stab Wound to the Medulla Oblongata Caused by a Pair of Scissors: Case Illustration

A 78-year-old male patient with a history of psychotic depression was found in the bathroom of his apartment with a pair of scissors driven deeply into the back of his neck. He presented with tetraparesis with residual control over the left lower limb movement. Immediate skull radiograph and brain computed tomography scans revealed the tip of the scissors passing into the foramen magnum. Emergent surgery with midline suboccipital craniectomy and resection of the posterior arch of C1 was performed. The scissors were spontaneously dislocated in the course of surgery. Thereafter, debridement, placement of external ventricular drain and primary closure of the dura and skin were achieved. Post-operatively, the patient was not able to follow any instructions. On the 22nd post-operative day, the patient passed away in palliation. To our knowledge, this is the first reported case of a suicide attempt involving the use of scissors reaching the medulla oblongata.

Cerebrospinal Fluid Dynamics Study: A Unique Tool for Management of Chiari 1 Malformation Patients

Background and Aim: Chiari I malformation(CIM) is defined as descent of cerebellar tonsils 5mm or more below the foramen magnum, with or without associated syrinx. Degree of tonsillar descent has a poor correlation with the progression of disease and symptomatology. Abnormal CSF dynamics at foramen magnum is the main pathophysiological factor responsible for the progression of tonsillar descent, syrinx formation and hence symptomatology. The aim of this study is to correlate CSF dynamic changes with the clinicoradiological profile of CIM patients. Methods and Materials/Patients: A prospective longitudinal study was done in 25 patients of CIM out of which 24 patients underwent standard midline suboccipital craniectomy with augmented duraplasty and 1 patient had ventriculoperitoneal shunt surgery for hydrocephalus. CSF flow study was done in sagittal as well as in axial sections at the level of foramen magnum using cine flow magnetic resonance imaging (MRI). Clinical and radiological assessment in reference to CSF flow parameters was done before and after decompression surgery. Results: After suboccipital decompression 23 out of 24 patients had relief in their symptoms and 1 patient had progressive syringomyelia. Postoperative MRI scan at 3months showed round shaped tonsils in all 24 patients. Ten out of 11 patients with syrinx had reduction in diameter of syrinx cavity. Peak CSF flow velocities reduced significantly (p value &lt; 0.05) in the postoperative period and correlated well with the clinicoradiological improvement. Conclusion: Abnormal CSF flow dynamics is responsible for the progression of disease and symptomatology in CIM patients. Cine flow MRI is a useful tool in the management of CIM patients both for proper selection of surgical candidates and in post-operative follow-up.

Chiari Malformation Type 1 in Adults Managed by Surgical Decompression: New Prospective

Aim of the work: This study aims to assess the value of the surgical management in the improvement of the symptoms & signs of patients with Chiari malformation type 1 and radiological follow up in adults. Patients and methods: This study included 30 consecutive patients with Chiari malformation type I who were indicated for surgery at neurosurgery department. Data were collected prospectively from the involved patients who were evaluated preoperatively and underwent evaluation by CT scanning of the brain & skull and MRI imaging of the brain and spine. CT and MRI were done as the routine follow up investigations for all patients. We operated through midline suboccipital craniectomy, durotomy in y shaped manner, shrinkage of cerebellar tonsils by bipolar electrocautery, duroplasty by fascia lata graft, watertight closure. Results: The assessment from E. J. N. S. (Egyptian Journal of Neurosurgery) vol. 24 no. 2 June 2009 used for evaluating the patients clinically. 18 patients reported good outcome, 6 fair, 6 poor. We evaluated the size of the syrinx if present preoperative in follow up. 15 (50%) patients showed marked reduction (more than or equal to 60%) in size of syrinx, 3 (10%) mild reduction (less than or equal to 30%) in size and 12 (40%) with no change. Conclusion: The Chiari type 1 malformation constitutes a controllable malformation with good outcomes. With current microsurgical techniques, the results of the bony decompression and duroplasty became excellent. Before undergoing surgical treatment for CM-I, symptomatic patients and their families should be given clear information about the success of treatment and potential complications.

Crescent durotomy for midline posterior fossa lesions.

The conventional midline suboccipital craniectomy, the standard approach for posterior fossa lesions, involves ligation of the occipital sinus. Postoperative sequelae that could occur from ligation of the occipital sinus include hydrocephalus, cerebrospinal fluid (CSF) leak, and pseudomeningiocoele formation. The standard of practice of venous pathway preservation, as practiced elsewhere in the cranium, should also be attempted in the posterior fossa. In the current study, we compared postsurgical complications between conventional "Y" durotomy with the proposed crescent durotomy in patients with posterior fossa lesions who underwent midline suboccipital craniectomy. The prospective data of 104 patients who underwent a midline suboccipital craniotomy for posterior fossa tumors between January 2011 and December 2015 was performed. Comparison of study variables was done between the durotomy techniques used. Of the 104 patients who formed the study population, 39 (37.5%) were women. While 75 patients underwent crescent durotomy, the remaining underwent the conventional "Y" durotomy. Among the postsurgical complications, there were no differences between groups in terms of their surgical site hematoma (2.7% vs 3.4%; P = 1.000) and edema (1.3% vs 0.0%; P = 1.000). The groups were also similar in terms of the incidence of postsurgical CSF leak (1.3% vs 6.9%; P = 0.187) and cranial nerve deficits (4.0% vs 6.9%; P = 0.617). However, more number of patients who underwent the "Y" durotomy had postoperative pseudomeningiocoele (2.7% vs 17.2%; P = 0.017). The "crescent" durotomy is a novel dural opening technique which attempts to preserve the normal venous flow physiology. The crescent durotomy reduces the need for a duroplasty, facilitates a comfortable primary closure, thus reducing the risk of developing a postoperative pseudomeningiocoele.

Brain-stem hemangioblastomas: The seemingly innocuous lesion in a perilous location.

Hemangioblastomas [75% sporadic, 25% with Von Hippel Lindau (VHL) disease] are highly vascular, benign lesions. The surgical nuances, management, and complication avoidance in brain-stem hemangioblastomas (BHs) have been studied. Over 18 years, 27(mean age: 29 years; range 15-60 years) consecutive cases of BH underwent microsurgical excision. All patients were assessed clinico-radiologically for neurological deficits and screened for VHL disease. Outcome of the patients was based on Karnofsky Performance Status scale (KPS). 12 out of 19 (70.4%) patients with hydrocephalus underwent a cerebrospinal fluid (CSF) diversion procedure. Lower cranial nerve palsy was present in 10 (37%) patients and motor weakness in 13 (48%). The tumours [mean size 3.34 ± 1.06 cm, range: 1.4-5.5 cm; 11 solid, rest solid-cystic; 18 (66.7%) subpial and 9 (33.33%) intramedullary] were divided into four categories based on size: A: <2 cm (n = 5,18.5%); B: 2-3 cm (n = 10,37%); C: 3-4 cm (n = 6,22.2%); D: >4 cm (n = 6,22.2%). Their location was at posterior cervicomedullary junction (n = 12); pontomedullary junction (n = 7); pons (n = 3), medulla (n = 3) and ponto-mesencephalic region (n = 2). Multiple flow voids were seen in >50% patients with tumour >2 cm. 5 patients had syringomyelia; and, 8 had diffuse cervical cord expansion. Two patients with a large vascular tumour underwent preoperative embolization. Six patients had VHL disease; one underwent bilateral adrenalectomy for refractory hypertension; and, the another, nephrectomy for renal cell carcinoma. Twenty-six patients underwent a midline suboccipital craniectomy; and, 1 with a cerebellopontine angle tumour, a retromastoid craniectomy. 15 patients underwent total excision; 10 patients, near-total (<10% remaining) excision, and 2 patients, a subtotal (>10% remaining)) excision. Three patients (2 with VHL disease) expired due to exsanguinating hemorrhage, spreading venous thrombosis and aspiration pneumonitis, respectively. At follow-up visit (median: 25 ± interquartile range 2-56months), 17 patients had improved KPS, 4 remained in same status and 3 (recently operated, on tracheostomy) had worsened KPS. Significant improvement is achievable in neurological status in patients following successful extirpation of a brain-stem hemangioblastoma, despite a turbulent perioperative period. Leaving tumour capsule adherent to the brain-stem often helps in preserving brain-stem function. Postoperatively, the patients should be monitored for their respiratory and lower cranial nerve status to prevent aspiration pneumonitis.

Neurofibromatosis type 1 and Chiari type 1 malformation: A case report and literature review of a rare association.

Background:The association between neurofibromatosis type 1 (NF-I) and Chiari I malformation (CMI) is rare, and not many studies are reported in the literature. Performing magnetic resonance imaging (MRI) in patients with NF-1 is essential because several cases of Chiari type I are completely asymptomatic. We emphasize the need for inclusion of Chiari I as diagnosis in association with NF-1.Case Description:The patient was a 51-year-old black man who presented with complaints of pain and decreased motion and sensibility of his hands, wrists, and forearms, along with progressive dysarthria. Even though the computed tomography (CT) scan of the skull did not show changes, the MRI showed hydro/syringomyelia in the cervical spine area. Midline suboccipital craniectomy with total laminectomy of c1 and partial laminectomy of c2 was performed; tonsillectomy was also performed for cistern expansion because of intense thickening and obliteration of the obex by the cerebellar tonsils. Following treatment, the patient showed remission of symptoms.Conclusion:NF-1 in association with CMI is rare, and early diagnosis and surgical treatment are essential to slow down the myelopathy; although they prevent neurological damages, patients with NF-1 must remain under doctor's attention in case of association with CMI. Our literature review showed that symptoms can vary and include headache, gait disturbance, and sensory/motor diminution, until asymptomatic patients. Moreover, the incidence of NF-1 is considerably higher in CMI patients in comparison to the global incidence (8.6–11.8% and 0.775%, respectively). The surgical technique must be evaluated case by case according to the degree of cerebrospinal fluid obstruction.

Total Excision of a Giant Ventral Midline Cervical Spinal Intradural Schwannoma via Posterior Approach.

Schwannomas are the most common intradural extramedullary tumors of the spine. They usually occupy a posterolateral or lateral position in relation to the cord. The ventral midline is a very rare location for the origin of a spinal schwannoma. A giant one in such a location causes technical difficulties in excision. Here, we present a giant cervical spinal schwannoma, located ventral to the cord, in a 38-year-old lady who presented with features of myelopathy and bladder involvement. Magnetic resonance imaging was suggestive of an intradural extramedullary lesion extending from cervico-medullary junction to the third dorsal vertebral level with severe cord compression. The same was excised totally via a posterior approach after midline suboccipital craniectomy and C2–C6 laminoplasty. Postoperatively, she made a good recovery and was ambulant without support. Postoperative magnetic resonance imaging showed complete excision of the tumor. Histopathology was suggestive of schwannoma.

Remote Cerebellar Infarction after Supratentorial Craniotomy and Its Management: Two Case Reports.

The cerebellar infarction resulting from supratentorial craniotomy is uncommon event and its management has been controversial. After removal of space occupying lesion on right frontal area, two cases of remote cerebellar infarctions occurred. We reviewed each cases and the techniques to manage such complications are discussed. Early extraventricular catheter insertion and midline suboccipital craniectomy were effectively performed in obtunded patients from cerebellar infarction.

Schwannoma originating in lateral recess of the fourth ventricle

Intracranial schwannomas most commonly occur in relation to vestibular nerves followed by trigeminal nerves. Authors describe a very unusual case of schwannomas originating in lateral recess of the fourth ventricle. Tumor was completely excised micro-surgically via midline suboccipital craniectomy and C1 laminectomy. Dissection of the surgical specimen revealed that the tumor was completely free from surrounding structures and just hanging in the fourth ventricle. It was not attached to any cranial nerves, brain parenchyma, and blood vessel or to the dura mater. Histopathological examination confirmed the diagnosis of schwannoma. To our knowledge, no such case has been reported so far from this extremely rare location. Relevant literature is reviewed and hypothesis for ectopic location of these tumors has been highlighted.

Crescent posterior fossa durotomy for occipito-marginal venous sinus preservation: A pilot study

The standard approach of midline suboccipital craniectomy entails sacrifice of the Occipito-marginal sinus. We have attempted to preserve this venous channel by using a durotomy technique which preserves this system. In a pilot study initiative, two groups of patients using this technique versus the standard approach, were compared in terms of per and post operative benefits, morbidity and complications. The literature with reference to the anatomy and venous flow dynamics of the occipital and marginal sinuses and their significance has been reviewed. Similarly, literature regarding dural closure technique with reference to postoperative complications has also been reviewed. In this novel approach, the dura is opened as a crescent to avoid damage to the occipital sinus. This technique was compared with the standard midline dural opening technique by random usage of both techniques in 24 patients. The 'crescent' approach has been found to reduce the need for duroplasty, with comfortable primary closure and to reduce the risk of postoperative pseudomeningocele. This is a novel dural opening technique which attempts to preserve the normal venous flow physiology. In essence it helps in increased primary dural closures and reduction of Pseudomeningiocele/CSF leak as well as blood loss and venous hypertension.

Posterior inferior cerebellar artery aneurysms: Anatomical variations and surgical strategies

Context:Posterior inferior cerebellar artery (PICA) aneurysms are associated with multiple anatomical variations of the parent vessel. Complexities in their surgical clipping relate to narrow corridors limited by brain-stem, petrous-occipital bones, and multiple neurovascular structures occupying the cerebellomedullary and cerebellopontine cisterns.Aims:The present study focuses on surgical considerations during clipping of saccular PICA aneurysms.Setting and Design:Tertiary care, retrospective study.Materials and Methods:In 20 patients with PICA aneurysms, CT angiogram/digital substraction angiogram was used to correlate the site and anatomical variations of aneurysms located on different segments of PICA with the approach selected, the difficulties encountered and the final outcome.Statistical Analysis:Comparison of means and percentages.Results:Aneurysms were located on PICA at: vertebral artery/basilar artery (VA/BA)-PICA (n=5); anterior medullary (n=4); lateral medullary (n=3); tonsillomedullary (n=4); and, telovelotonsillar (n=4) segments. The Hunt and Hess grade distribution was I in 15; II in 2; and, III in 3 patients (mean ictus-surgery interval: 23.5 days; range: 3-150 days). Eight patients had hydrocephalus. Anatomical variations included giant, thrombosed aneurysms; 2 PICA aneurysms proximal to an arteriovenous malformation; bilobed or multiple aneurysms; low PICA situated at the foramen magnum with a hypoplastic VA; and fenestrated PICA. The approaches included a retromastoid suboccipital craniectomy (n=9); midline suboccipital craniectomy (n=6); and far-lateral approach (n=5). At a follow-up (range 6 months-2.5 years), 13 patients had no deficits (modified Rankin score (mRS) 0); 2 were symptomatic with no significant disability (mRS1); 1 had mild disability (mRS2); 1 had moderately severe disability (mRS4); and 3 died (mRS6). Three mortalities were caused by vasospasm (2) and, rupture of unclipped second VA-BA junctional aneurysm (1).Conclusions:PICA aneurysms may present with only IVth ventricular blood without subarachnoid hemorrhage. PICA may have multiple anomalies and its aneurysms may be missed on CT angiograms. Surgical approach is influenced by VA-BA tortuosity and variations in anatomy, location of the VA-BA junction and the PICA aneurysm relative to the brain-stem, and the pattern of collateral supply. The special category of VA-PICA junctional aneurysms and its management; and, the multiple anatomical variations of PICA aneurysms, merit special surgical considerations and have been highlighted in this study.

Chiari Malformation- Report of 3 Cases

3 cases of chiari malformation type-I were presented with classical picture of spasticity, quadriparesis and dissociated sensory loss and were operated ( Craniovertebral junction decompression by midline suboccipital craniectomy with removal of C1 arch and duroplasty). All the 3 patients were improved. Among them one patient recovered with some morbidity for postoperative other diseases.&#x0D; TAJ 2010; 23(1): 84-86

Surgery in sitting position in patient with ventriculoperitoneal shunt in situ may be hazardous!

Dear Editor: Complications in sitting position are encountered more often than other surgical positions [1]. Literature search did not reveal any case demonstrating development of an extradural hematoma as a result of surgery in sitting position. We report a case of a 4-year-old female child, weighing 10 kg, admitted in our neurosurgical ward with complaints of headache, vomiting, and difficulty in walking for the last 6 months. A magnetic resonance image scan revealed a contrast enhanced lesion in the pineal region suggestive of pineal tumor. She had earlier undergone endoscopic biopsy removal and a right ventriculoperitoneal shunt surgery. Her medical history was unremarkable, and all preoperative routine investigations were within normal limits. She was scheduled for an elective midline suboccipital craniectomy in sitting position. Following a standard fasting protocol, the child was premedicated with oral atropine 0.4 mg, an hour before surgery. Inside the operation theater routine monitors were attached. General anesthesia was induced with fentanyl 20 mcg and thiopentone 50 mg. To facilitate tracheal intubation with cuffed tube size 5.0, rocuronium 10 mg was administered. Anesthesia was maintained with isoflurane in oxygen and nitrous oxide mixture and intermittent boli of fentanyl 1 mcg/kg and rocuronium 0.1 mg/kg. A double lumen central venous catheter was placed in the right subclavian vein. An arterial line placed in the right dorsalis pedis artery allowed continuous monitoring of blood pressure. The child was placed in sitting position with head supported in a three-pin head rest. A near total excision of the tumor was performed by supracerebellar infratentorial approach. The surgical and anesthetic course lasting approximately 4 h was uneventful. There was no episode of venous air embolism. It was planned to mechanically ventilate the lungs until spontaneous reversal of neuromuscular blockade. The patient was shifted for routine CT scan postoperatively, which revealed a large pneumocephalus (Fig. 1a) along with a high right parietal hematoma measuring 4.8× 1.3 cm (Fig. 1b). However, there was no midline shift and mass effect visible on the scan. A burr hole evacuation of hematoma was performed, and patient was weaned off mechanical ventilation on the second postoperative day. A repeat CT scan revealed resolving pneumocephalus, and no other abnormality. We believe that the ventriculoperitoneal shunt tube in situ may have resulted in such a complication. Excessive drainage of cerebrospinal fluid via the drain could have resulted in intracranial hypotension causing rupture of bridging veins, leading to hematoma formation. H. Prabhakar :G. P. Singh :A. Bindra Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi, India 110029

Aneurysms from extracranial, extradurally originating posterior inferior cerebellar arteries: a rare case report

Background Aneurysms arising from the PICA are infrequent and those arising from an extracranially originating PICA in the extracranial intradural region are even rare. We report a case of bilaterally extracranial extradurally originating PICAs, each of which had an aneurysm, both being situated below the foramen magnum. This to the best of our knowledge is the first of its kind to be reported. Case Description A 35-year-old woman presented with giddiness and headache of 2-day duration. CT scan head revealed blood in the 4 th ventricle. 4 vessel angiogram revealed bilateral extracranial, extradural origin of PICAs from the vertebral arteries between C1 and C2 vertebrae. Both PICAs were associated with a saccular aneurysm each, both of which were extracranial. She underwent a midline suboccipital craniectomy, C1 arch excision, and clipping of both aneurysms. Conclusions We report a very rare case of bilateral extracranial PICA aneurysms from an aberrantly originating PICA (ie, extracranial and extradural).

Primary midbrain germinoma

An 11-year-old boy presented with a 4-month history of progressive holocranial headache, intermittent vomiting and visual blurring. Later, he began walking unsteadily, with progressive bilateral visual and hearing loss. He had had two episodes of abnormal tonic posturing the day prior to admission. On examination, the patient was drowsy and did not respond to commands. Imaging showed an enhancing midbrain mass with an exophytic component with hydrocephalus. Emergency ventriculoperitoneal shunt was performed, following which there was neurological improvement. Later he underwent a midline suboccipital craniectomy with vermian splitting and decompression of the exophytic component of the tumor from the midbrain. Biopsy of the tumor revealed a germinoma. Post-operatively, the patient received chemotherapy followed by radiotherapy. Primary midbrain germinoma is an extremely rare entity and to the best of our knowledge only two cases to date have been reported in the literature.

Epidural hematoma following use of a three-point skull clamp

We report an unusual case of epidural hematoma secondary to the use of a three-point skull-fixation device. Initially, a posterior-fossa brain tumor with hydrocephalus was diagnosed in a 15-year-old boy. Midline suboccipital craniectomy was performed with the patient placed in the prone position. A Mayfield (Ohio Medical Instrument Co., Cincinnati, OH, USA) skull clamp was used for fixation of the head during the surgical procedure, following which, a huge epidural hematoma developed within 6 hours of surgery, due to skull penetration and fracture at one of the clamp’s pin sites located proximate to the coronal suture.

Intraventricular meningiomas: A surgical challenge

Background Primary intraventricular meningiomas (IVM) pose a surgical challenge as they often remain asymptomatic until they become very large; have close proximity to vital intraventricular structures; and, their vascular supply is often encountered only after significant tumor debulking. In this study, the surgical management of IVM is discussed. Methods Between 1989 and 2003, nine patients (7 with lateral and 2 with fourth ventricular) IVM, were operated upon. Raised intracranial pressure, gait ataxia, memory impairment, seizures (motor and sensory) were the main presentations. Four had hydrocephalus while five had either a sequestered temporal or occipital horn. All were large tumors with an average size more than 5.3 cm. The lateral ventricular IVM were accessed by the posterior middle temporal gyrus ( n = 5) or the superior parietal lobule ( n = 2) approach. A midline suboccipital craniectomy was used for the fourth ventricular IVM. Results Total excision was achieved in eight and partial excision in one. Patients with lateral ventricular tumors required a postoperative intraventricular drain for a minimum period of 48 hours. The main morbidity included visual field defects and transient hemiparesis, seizure and meningitis. The one patient with partial excision died 6 weeks later due to transtentorial herniation as a result of intratumoral bleed and lateral ventricular sequestration. Conclusions An IVM, being initially asymptomatic, usually attains a large size before detection. During surgery, its devascularisation is usually achieved only after significant tumor debulking. Development of hydrocephalus or ventricular sequestration should be constantly monitored and may be avoided in the postoperative period by continuous external ventricular drainage.

Arachnoid cyst within the fourth ventricle: a case report

The authors report a case of fourth ventricular arachnoid cyst that presented clinically with the criteria of normal pressure hydrocephalus. Only a few cases of intraventricular arachnoid cyst have been recorded in the literature. In our case, a posterior approach was used via a midline suboccipital craniectomy and the cyst was excised.