Arachnoid cysts are common, accounting for approximately 1% of intracranial mass lesions. Most are congenital, clinically silent, and remain static in size. Occasionally, they increase in size and produce symptoms due to mass effect or obstruction. The mechanism of enlargement of arachnoid cysts is controversial. One-way slit valves are often hypothesized as the mechanism for enlargement. The authors present 4 cases of suprasellar prepontine arachnoid cysts in which a slit valve was identified. The patients presented with hydrocephalus due to enlargement of the cyst. The valve was located in the arachnoid wall of the cyst directly over the basilar artery. The authors believe this slit valve was responsible for the net influx of CSF into the cyst and for its enlargement. They also present 1 case of an arachnoid cyst in the middle cranial fossa that had a small circular opening but lacked a slit valve. This cyst did not enlarge but surgery was required because of rupture and the development of a subdural hygroma. One-way slit valves exist and are a possible mechanism of enlargement of suprasellar prepontine arachnoid cysts. The valve was located directly over the basilar artery in each of these cases. Caudad-to-cephalad CSF flow during the cardiac cycle increased the opening of the valve, whereas cephalad-to-caudad CSF flow during the remainder of the cardiac cycle pushed the slit opening against the basilar artery and decreased the size of the opening. Arachnoid cysts that communicate CSF via circular, nonslit valves are probably more likely to remain stable.
Report of 5 cases
Sameer H. Halani, Mina G. Safain and Carl B. Heilman
Mina G. Safain, Walter C. Dent and Carl B. Heilman
Epidermoid cysts are rare lesions accounting for 1% of intracranial tumors with approximately 50% located within the cerebello-pontine angle (CPA). Resection is complicated by their close anatomical relation to critical neurovascular structures and their tendency to be densely adherent making complete removal a significant neurosurgical challenge. We present a 35-year-old woman with left sided tongue numbness and lower lip paresthesias with a CPA epidermoid. An endoscopic assisted retrosigmoid approach was utilized for resection. A 30-degree endoscope was used to assist in removal of unseen tumor in Meckel's cave, medial to the lower cranial nerves, and along the ventral pons.
The video can be found here: http://youtu.be/bv0lMPbX7BY.
Shane M. Burke, Mina G. Safain, James Kryzanski and Ron I. Riesenburger
Lumbar nerve root anomalies are uncommon phenomena that must be recognized to avoid neural injury during surgery. The authors describe 2 cases of nerve root anomalies encountered during mini-open transforaminal lumbar interbody fusion (TLIF) surgery. One anomaly was a confluent variant not previously classified; the authors suggest that this variant be reflected in an amendment to the Neidre and Macnab classification system. They also propose strategies for identifying these anomalies and avoiding injury to anomalous nerve roots during TLIF surgery. Case 1 involved a 68-year-old woman with a 2-year history of neurogenic claudication. An MR image demonstrated L4–5 stenosis and spondylolisthesis and an L-4 nerve root that appeared unusually low in the neural foramen. During a mini-open TLIF procedure, a nerve root anomaly was seen. Six months after surgery this patient was free of neurogenic claudication. Case 2 involved a 60-year-old woman with a 1-year history of left L-4 radicular pain. Both MR and CT images demonstrated severe left L-4 foraminal stenosis and focal scoliosis. Before surgery, a nerve root anomaly was not detected, but during a unilateral mini-open TLIF procedure, a confluent nerve root was identified. Two years after surgery, this patient was free of radicular pain.
Mina G. Safain, Jordan Talan, Adel M. Malek and Steven W. Hwang
Vertebral artery (VA) occlusion is a serious and potentially life-threatening occurrence. Bow hunter's syndrome, a mechanical occlusion of the VA due to physiological head rotation, has been well described in the medical literature. However, mechanical VA compression due to routine flexion or extension of the neck has not been previously reported. The authors present the unique case of a woman without any history of trauma who had multiple posterior fossa strokes and was found to have dynamic occlusion of her right VA visualized via cerebral angiogram upon extension of her neck. This occlusion was attributed to instability at the occipitocervical junction in a patient with a previously unknown congenital fusion of both the occiput to C-1 and C-2 to C-3. An occiput to C-3 fusion was performed to stabilize her cervical spine and minimize the dynamic vascular compression. A postoperative angiogram showed no evidence of restricted flow with flexion or extension of the neck. This case emphasizes the importance of considering symptoms of vertebrobasilar insufficiency as a result of physiological head movement. The authors also review the literature on VA compression resulting from physiological head movement as well as strategies for clinical diagnosis and treatment.
Steven W. Hwang, Mina G. Safain, Joseph J. King, Jeff S. Kimball, Robert Ames, Randall R. Betz, Patrick J. Cahill and Amer F. Samdani
Almost all pediatric patients who incur a spinal cord injury (SCI) will develop scoliosis, and younger patients are at highest risk for curve progression requiring surgical intervention. Although the use of pedicle screws is increasing in popularity, their impact on SCI-related scoliosis has not been described. The authors retrospectively reviewed the radiographic outcomes of pedicle screw–only constructs in all patients who had undergone SCI-related scoliosis correction at a single institution.
Medical records and radiographs from Shriner's Hospital for Children–Philadelphia for the period between November 2004 and February 2011 were retrospectively reviewed.
Thirty-seven patients, whose mean age at the index surgery was 14.91 ± 3.29 years, were identified. The cohort had a mean follow-up of 33.2 ± 22.8 months. The mean preoperative coronal Cobb angle was 65.5° ± 25.7°, which corrected to 20.3° ± 14.4°, translating into a 69% correction (p < 0.05). The preoperative coronal balance was 24.4 ± 22.6 mm, with a postoperative measurement of 21.6 ± 20.7 mm (p = 1.00). Preoperative pelvic obliquity was 12.7° ± 8.7°, which corrected to 4.1° ± 3.8°, translating into a 68% correction (p < 0.05). Preoperative shoulder balance, as measured by the clavicle angle, was 8.2° ± 8.4°, which corrected to 2.7° ± 3.1° (67% correction, p < 0.05). Preoperatively, thoracic kyphosis measured 44.2° ± 23.7° and was 33.8° ± 11.5° postoperatively. Thoracolumbar kyphosis was 18.7° ± 12.1° preoperatively, reduced to 8.1° ± 7.7° postoperatively, and measured 26.8° ± 20.2° at the last follow-up (p < 0.05). Preoperatively, lumbar lordosis was 35.3° ± 22.0°, which remained stable at 35.6° ± 15.0° postoperatively.
Pedicle screw constructs appear to provide better correction of coronal parameters than historically reported and provide significant improvement of sagittal kyphosis as well. Although pedicle screws appear to provide good radiographic results, correlation with clinical outcomes is necessary to determine the true impact of pedicle screw constructs on SCI-related scoliosis correction.
Mina G. Safain, Jason P. Rahal, Samir Patel, Alexandra Lauric, Edward Feldmann and Adel M. Malek
Intracranial atherosclerotic disease (ICAD) carries a high risk of stroke. Evaluation of ICAD has focused on assessing the absolute degree of stenosis, although plaque morphology has recently demonstrated increasing relevance. The authors provide the first report of the use of ultra-high-resolution C-arm cone-beam CT angiography (CBCT-A) in the evaluation of vessel stenosis as well as plaque morphology.
Between August 2009 and July 2012, CBCT-A was used in all patients with ICAD who underwent catheter-based angiography at the authors' institution (n = 18). Lesions were evaluated for maximum degree of stenosis as well as plaque morphological characteristics (ulcerated, calcified, dissected, or spiculated) via digital subtraction angiography (DSA), 3D-rotational angiography (3DRA), and CBCT-A. The different imaging modalities were compared in their assessment of absolute stenosis as well as their ability to resolve different plaque morphologies.
Lesions were found to have similar degrees of stenosis when utilizing CBCT-A compared with 3DRA, but both 3DRA and CBCT-A differed from DSA in their assessment of the absolute degree of stenosis. CBCT-A provided the most detailed resolution of plaque morphology, identifying a new plaque characteristic in 61% of patients (n = 11) when compared with DSA and 50% (n = 9) when compared with 3DRA. CBCT-A identified all lesion characteristics visualized on DSA and 3DRA.
CBCT-A provides detailed spatial resolution of plaque morphology and may add to DSA and 3DRA in the evaluation of ICAD. Further prospective study is warranted to determine any benefit CBCTA-A may provide in clinical decision making and risk stratification over existing conventional imaging modalities.
Mina G. Safain, Shane M. Burke, Ron I. Riesenburger, Vasilios Zerris and Steven W. Hwang
The standard surgical release of a tethered cord may result in recurrent scar formation and occasionally be associated with retethering. The application of spinal shortening procedures to this challenging problem potentially can reduce tension on the retethered spinal cord while minimizing the difficulties inherent in traditional lumbosacral detethering revision. Although spinal shortening procedures have proven clinical benefit in patients with a recurrent tethered cord, it is unclear how much shortening is required to achieve adequate reduction in spinal cord tension or what impact these osteotomies have on dural buckling.
The authors calculated mean values from 4 human cadavers to evaluate the effect of 3 different spinal shortening procedures—Smith-Petersen osteotomy (SPO), pedicle subtraction osteotomy (PSO), and vertebral column resection (VCR)—on spinal cord tension and dural buckling. Three cadavers were dedicated to the measurement of spinal cord tension, and 3 other cadavers were devoted to myelography to measure dural buckling parameters.
The SPO was associated with a maximal decrease in spinal cord tension of 16.1% from baseline and no dural buckling with any degree of closure. The PSO led to a mean maximal decrease in spinal cord tension of 63.1% from baseline at 12 mm of closure and demonstrated a direct linear relationship between dural buckling and increasing osteotomy closure. Finally, VCR closure correlated with a mean maximal decrease in spinal cord tension of 87.2% from baseline at 10 mm of closure and also showed a direct linear relationship between dural buckling and increases in osteotomy closure.
In this cadaveric experiment, the SPO did not lead to appreciable tension reduction, while a substantial response was seen with both the PSO and VCR. The rate of tension reduction may be steeper for the VCR than the PSO. Adequate tension relief while minimizing dural buckling may be optimal with 12–16 mm of posterior osteotomy closure based on this cadaveric experiment.
Robert S. Heller, Claire M. Lawlor, Thomas R. Hedges III, Yanik J. Bababekov, Mina G. Safain and Adel M. Malek
The benefits of treating intracranial aneurysms in the region of the anterior visual pathways are well understood. However, the adverse effects of endovascular stenting across the ophthalmic artery have received little attention. The authors reviewed their experience with patients who had stents deployed across the ophthalmic artery origin.
Patients' medical charts and imaging studies were reviewed to identify all patients with a non–flow diverting stent deployed over the ophthalmic artery origin for the treatment of intracranial aneurysms. All patients with neuro-ophthalmic complaints were referred for formal ophthalmological evaluation.
A total of 104 consecutive patients with 106 aneurysms were identified to meet criteria for inclusion in the study cohort. Preoperatively, 30 patients (29%) described headache symptoms and 32 patients (31%) reported visual complaints. Of the patients with preoperative headaches, 15 (54%) of 28 patients for whom follow-up was available experienced improvement in their symptoms. Of the patients with preoperative visual complaints, improvement was noted in 11 (41%) of the 27 patients for whom follow-up was available, 9 (33%) of 27 patients reported no change in visual symptoms, and 7 (26%) of 27 patients reported progression of symptoms. Visual field defects developing posttreatment were noted to occur in 8 (7.7%) of 104 patients: 3 with immediate postoperative retinal infarcts, 1 with perioperative hemianopia that resolved by the time of discharge, 1 with a subjective visual field defect, 1 with subjective migratory visual field defects, and 2 with nonspecific visual symptoms. Compressive symptoms from aneurysm mass effect were noted in 6 patients preoperatively, with 4 of those patients experiencing persistent worsening, resolution in 1 case, and no change in 1 case. One patient developed a novel cranial nerve palsy from mass effect in the immediate postoperative period.
Deployment of stents across the ophthalmic artery origin for the treatment of intracranial aneurysms appears to be relatively safe with regard to visual outcomes. Neuro-ophthalmic complaint resolution rates were comparable to endovascular procedures that do not employ stents, with headache resolution rates comparable to coil-only aneurysm obliteration and low rates of retinal ischemic events. For patients presenting with mass effect, stent-assisted coiling appears to be less effective than microsurgery with decompression for relief of compressive symptoms.
Ali O. Jamshidi, André Beer-Furlan, Daniel M. Prevedello, Ronald Sahyouni, Mohamed A. Elzoghby, Mina G. Safain, Ricardo L. Carrau, John A. Jane Jr. and Edward R. Laws
The endoscopic endonasal approach has been proposed as a primary surgical strategy for select craniopharyngiomas. However, those tumors that arise from the sella have not been classified with the other craniopharyngioma subtypes in terms of surgical nuances, intraoperative findings, and postoperative outcomes. The authors describe their experience with a select subtype of craniopharyngioma arising within the sella subjacent to the diaphragma sellae and refer to these tumors as type 0.
After obtaining IRB approval, three institutions retrospectively reviewed their data collected from 2005 to 2017. Patients eligible for inclusion in the study were those who had tumors that originated from the sella inferior to the diaphragma sellae. Demographic, clinical, radiological, surgical, and follow-up data were examined and analyzed.
Twenty-eight patients (average age 19.3 years, range 3–60 years) were included in this study. Sixteen patients (57%) were younger than 18 years of age. All patients had characteristic imaging features of an expanded sella. Seventy-five percent of the patients presented with some form of visual field deficit (89% had radiographic optic apparatus compression) and 39% with hypopituitarism. The average maximal tumor diameter in the axial, coronal, or sagittal plane was 3.1 cm. Gross-total resection was achieved in 82% of the patients. Twenty-one percent of patients experienced an iatrogenic complication, and there were only two cases (7%) of postoperative cerebrospinal fluid (CSF) leakage. Only two patients (7%) required the use of a nasoseptal flap as part of their original reconstruction. Pathology was uniformly the adamantinomatous subtype. Postoperative objective visual outcomes were improved in 71% of the patients with visual symptoms or visual field deficits on presentation and stable in 24%. Mean follow-up was 45.1 months (range 3–120 months) with an 18% recurrence rate at a mean of 44.4 months (range 10–84 months). One patient was lost to follow-up. Thirty-six percent of patients received postoperative radiation to treat recurrence or residual tumor. Endocrine data are also presented.
Craniopharyngiomas that originate within the sella below the diaphragma sellae are a select subtype characterized by 1) an enlarged sella, 2) an intact diaphragma sellae at surgery, and 3) an adamantinomatous pathology. These tumors can be treated transnasally without the absolute need for neurovascular flap reconstruction, as there is a low risk of CSF leakage.
Fatih Tütüncü, Sarah Schimansky, Merih I. Baharoglu, Bulang Gao, Daniel Calnan, James Hippelheuser, Mina G. Safain, Alexandra Lauric and Adel M. Malek
Arterial bifurcations represent preferred locations for aneurysm formation, especially when they are associated with variations in divider geometry. The authors hypothesized a link between basilar apex aneurysms and basilar bifurcation (α) and vertebrobasilar junction (VBJ) angles.
The α and VBJ angles were measured in 3D MR and rotational angiographic volumes using a coplanar 3-point technique. Angle α was compared between age-matched cohorts in 45 patients with basilar artery (BA) aneurysms, 65 patients with aneurysms in other locations (non-BA), and 103 nonaneurysmal controls. Additional analysis was performed in 273 nonaneurysmal controls. Computational fluid dynamics (CFD) simulations were performed on parametric BA models with increasing angles.
Angle α was significantly wider in patients with BA aneurysms (146.7° ± 20.5°) than in those with non-BA aneurysms (111.7° ± 18°) and in controls (103° ± 20.6°) (p < 0.0001), whereas no difference was observed for the VBJ angle. A wider angle α correlated with BA aneurysm neck width but not dome size, which is consistent with CFD results showing a widening of the impingement zone at the bifurcation apex. BA bifurcations hosting even small aneurysms (< 5 mm) had a significantly larger α angle compared with matched controls (p < 0.0001). In nonaneurysmal controls, α increased with age (p < 0.0001), with a threshold effect above 35 years of age and a steeper dependence in females (p = 0.002) than males (p = 0.04).
The α angle widens with age during adulthood, especially in females. This angular widening is associated with basilar bifurcation aneurysms and may predispose individuals to aneurysm initiation by diffusing the flow impingement zone away from the protective medial band region of the flow divider.