Relationship between Cough-Associated Changes in CSF Flow and Disease Severity in Chiari I Malformation: An Exploratory Study Using Real-Time MRI.

BACKGROUND AND PURPOSE: Currently no quantitative objective test exists to determine disease severity in a patient with Chiari I malformation. Our aim was to correlate disease severity in symptomatic patients with Chiari I malformation with cough-associated changes in CSF flow as measured with real-time MR imaging. MATERIALS AND METHODS: Thirteen symptomatic patients with Chiari I malformation (tonsillar herniation of ≥5 mm) were prospectively studied. A real-time, flow-sensitized pencil-beam MR imaging scan was used to measure CSF stroke volume during rest and immediately following coughing and relaxation periods (total scan time, 90 seconds). Multiple posterior fossa and craniocervical anatomic measurements were also obtained. Patients were classified into 2 groups by neurosurgeons blinded to MR imaging measurements: 1) nonspecific Chiari I malformation (5/13)-Chiari I malformation with nonspecific symptoms like non-cough-related or mild occasional cough-related headache, neck pain, dizziness, paresthesias, and/or trouble swallowing; 2) specific Chiari I malformation (8/13)-patients with Chiari I malformation with specific symptoms and/or objective findings like severe cough-related headache, myelopathy, syringomyelia, and muscle atrophy. The Spearman correlation was used to determine correlations between MR imaging measurements and disease severity, and both groups were also compared using a Mann-Whitney U test. RESULTS: There was a significant negative correlation between the percentage change in CSF stroke volume (resting to postcoughing) and Chiari I malformation disease severity (R = 0.59; P = .03). Mann-Whitney comparisons showed the percentage change in CSF stroke volume (resting to postcoughing) to be significantly different between patient groups (P = .04). No other CSF flow measurement or anatomic measure was significantly different between the groups. CONCLUSIONS: Our exploratory study suggests that assessment of CSF flow response to a coughing challenge has the potential to become a valuable objective noninvasive test for clinical assessment of disease severity in patients with Chiari I malformation.

Simultaneous noncontiguous cervical spine injuries in a pediatric patient: case report.

OBJECTIVE AND IMPORTANCE: Noncontiguous traumatic injuries of the cervical spine in children are rare. We present the case of a child who simultaneously sustained a separation of the odontoid synchondrosis and a C6-C7 dislocation with a complete spinal cord injury. The management of simultaneous cervical spine injuries is discussed. CLINICAL PRESENTATION: A boy aged 4 years and 2 months was a restrained back-seat passenger involved in a head-on motor vehicle accident. The patient lacked neurological function below C7. Imaging studies revealed a separation of the odontoid synchondrosis as well as a traumatic dislocation of the spine at C6-C7. INTERVENTION: The patient was placed in a halo vest shortly after admission. Four days after his injury, he underwent a posterior wiring and fusion of C6 to C7. As the C6-C7 dislocation was reduced by posterior element wiring, intraoperative x-rays showed a gradual increase in the subluxation of C1 on C2. This increase in C1-C2 subluxation required intraoperative repositioning of the halo crown on the ventral halo vest posts to maintain acceptable C1-C2 alignment. Postoperatively, ideal alignment of the odontoid peg on the body of C2 could not be achieved by halo adjustments alone. The patient required a custom-made posterior neck cushion attached to the halo vest to maintain cervical lordosis and good alignment of the odontoid peg on the body of C2. CONCLUSION: Simultaneous traumatic cervical spine injuries in pediatric patients are rare. The intraoperative reduction of one spine injury can affect the alignment at the location of the second injury. In this case, a custom adjustment of the halo vest improved the alignment of the odontoid peg on the body of C2.

Meningiomas of the cerebellopontine angle.

BACKGROUND: Meningiomas of the cerebellopontine angle (CPA), although uniform in location, are diverse with regard to the site of dural origin and displacement of neurovascular structures. A study of patients with CPA meningiomas was undertaken to gain more information regarding the relationship between site of dural attachment, clinical presentation, operative approach, and outcome. METHODS: In this report, we retrospectively review 40 patients with CPA meningiomas managed surgically. RESULTS: Common clinical presentations were hearing loss, unsteadiness, and dysequilibrium. Findings upon physical examination included hearing loss (73%), cerebellar signs (32%), trigeminal neuropathy (16%), and facial nerve dysfunction (16%). The most common site of dural origin was the petrous ridge (anterior to the IAC [26%], posterior [21%], superior [18%], and inferior [16%]). Less common sites of dural origin included the tentorium (31%), the clivus (15%), the IAC (10%), and the jugular foramen (8%). Site of dural origin determined the direction of displacement of the facial/vestibulocochlear nerve bundle. The most common microsurgical complication was facial nerve dysfunction (30%). Gross total resection was achieved in 82% of cases, whereas 18% underwent subtotal resection. Two patients died. Follow-up ranged from three months to 13 years with three recurrences. CONCLUSIONS: CPA meningiomas displace the seventh and eighth cranial nerves in various directions depending on the site of dural origin. Total surgical excision can be accomplished in the majority of cases with acceptable morbidity.

Bone flap fixation with titanium clamps: a new technique.

BACKGROUND: Craniotomy bone flaps are replaced for both cosmetic and protective purposes. The purpose of this study was to determine the facility, strength, timing, and cost effectiveness of an alternative system for securing bone flaps. The system consists of titanium discs that clamp the bone flap to the skull edge. METHODS AND RESULTS: Ten cadaver craniotomy flaps each were reattached with either 24-gauge wire, miniplates, or titanium clamps. The titanium clamp system required significantly less time to fix than either wire or miniplates. The clamps were stronger than wire and cost less than miniplates. CONCLUSION: The titanium clamp system is a reasonable alternative to present craniotomy fixation methods with respect to ease of use, time consumption, strength, and relative cost.

Intracranial mucocele as a complication of endoscopic repair of cerebrospinal fluid rhinorrhea: case report.

OBJECTIVE AND IMPORTANCE: Endoscopic repair of an anterior cranial fossa cerebrospinal fluid (CSF) fistula has gained widespread acceptance. We report a case of mucocele development at the site of an endoscopic CSF leak repair. CLINICAL PRESENTATION: A 46-year-old woman underwent functional endoscopic sinus surgery for nasal obstructive symptoms. The surgery was complicated by an intraoperative CSF leak from the posterior cribriform plate/anterior sphenoid, which was repaired immediately using bone and mucosa grafts. Two years postoperatively, a 13-mm anterior cranial base mass was found incidentally. This mass increased to 20 mm over the next year. INTERVENTION: The anterior cranial base mass was excised via a right frontal craniotomy and confirmed histologically to be a mucocele. CONCLUSION: Endoscopic repair of an anterior cranial base CSF fistula with mucosal grafts may lead to formation of a mucocele.

Temporal bone meningiomas.

Meningiomas involving the temporal bone may originate from arachnoid cell nests present within the temporal bone (intratemporal), but more frequently originate from arachnoid cell nests of the posterior or middle cranial fossa with secondary invasion of the TB (extratemporal). In this study, we retrospectively reviewed the charts of 13 patients with meningiomas involving the temporal bone who underwent surgery. Tumors of the posterior fossa with only temporal bone hyperostosis, but without invasion, were excluded. Patients presented primarily with otologic symptoms and signs. The tumors originated in the temporal bone (5/13), jugular foramen (4/13), petroclival region (2/13), the asterion (1/13) or the internal auditory meatus (1/13). All of the intratemporal meningiomas had the radiological appearance of en-plaque menigiomas. The tumor extended into the middle ear (11/13), eustachian tube (5/13), and/or the labyrinth (3/13). A gross total resection was achieved in 11 patients and a subtotal resection in 2 patients. The lower cranial nerves were infiltrated by tumor in 4 patients, and were sacrificed. At a mean follow-up of approximately 6 years, 12 patients are currently alive and doing well and 1 died from tumor progression. Six patients showed tumor recurrence and were reoperated on (5/6) or followed conservatively (1/6). Surgical treatment of temporal bone meningiomas is associated with high recurrence rate due to indiscreet tumor margins. Combined surgical approaches (temporal craniotomy and mastoidectomy) by neurosurgical and otological teams are recommended for meningiomas originating in the temporal bone.

Asterion meningiomas.

Asterion meningiomas arise from the posterior petrous ridge at the junction of the transverse and sigmoid sinuses (sinodural angle). The authors retrospectively reviewed the charts of seven patients with asterion meningiomas who underwent a Simpson I tumor resection by either the petrosal or suboccipital approach. Patients presented with headaches, dizziness, ataxia, or seizures. Preoperative angiograms and intraoperative observations confirmed occlusion of the transverse and sigmoid sinuses by tumor, thrombus, or both in four of the patients. In all cases, tumor infiltrated the sinuses and the sinuses were ligated without adverse sequelae. Temporal bone invasion was seen in one patient who had the only tumor recurrence. Postoperatively, there were two transient CSF leaks. Asterion meningiomas can be completely resected with a low incidence of major morbidity. In this small series, a patent transverse/sigmoid sinus was resected in three patients without sequelae. We believe that in young patients with asterion meningiomas a nondominant transverse/sigmoid sinus should be resected if the torcula is patent. More research is needed to determine the safety of resecting a patent dominant transverse/sigmoid sinus.

Endoscopic sphenoidotomy approach to the sella.

OBJECTIVE: Advances in optics, miniaturization, and endoscopic instrumentation have revolutionized surgery in the past decade. We report our experience with the endoscope in nine patients with sellar lesions who underwent an endoscopic sphenoidotomy approach to the sella. METHODS: An endoscopic transnasal cavity sphenoidotomy approach without a septal dissection was used in the resection of pituitary adenomas and other sellar lesions. RESULTS: This approach provided excellent exposure of the sella and adequate working space. The technique produces less postoperative pain and, in some cases, shortens hospital stay. The sphenoidotomy approach eliminates the problems of lip numbness, septal perforations, and oronasal fistulas. CONCLUSION: The endoscopic sphenoidotomy approach has become our preferred approach to sellar lesions.

Recurrence of medulloblastoma: violation of Collins' law after two decades.

BACKGROUND: Medulloblastoma is a common tumor of childhood arising in the posterior fossa. The concept of a child with an embryonal tumor surviving the age of diagnosis plus 9 months as the period of risk for recurrence (Collins' Law) has been applied to medulloblastomas. This raises the question of "when should follow-up stop for a patient with this type of tumor?" METHODS: We present a case report of a patient with the longest documented exception to Collins' Law for medulloblastoma. RESULTS: The longest documented exception to Collins' Law, a medulloblastoma recurring 20 years and 8 months after the period of risk for recurrence is presented. Both the site of recurrence and the histopathology were identical to the original tumor. CONCLUSION: We present the longest documented exception to Collins' Law, to emphasize that even after decades the term "cure" should only be used cautiously.

Endoscopically assisted prevention of cerebrospinal fluid leak in suboccipital acoustic neuroma surgery.

HYPOTHESIS: The purpose of this prospective study was to determine if direct inspection of air cells using endoscopy could reduce the occurrence of cerebrospinal fluid (CSF) leak in suboccipital acoustic neuroma surgery. BACKGROUND: Cerebrospinal fluid leak remains one of the most common complications after acoustic neuroma surgery. The suboccipital approach for excision of acoustic neuromas has been used increasingly since gadolinium-enhanced magnetic resonance imaging has improved the ability to diagnose smaller tumors. Suboccipital approaches are reported to have CSF leak rates of as high as 27% with an average rate of 12%, most presenting as rhinorrhea. Ideally, this complication could be avoided by careful closure of all air cells exposed during the approach, especially those commonly found in the posterior wall of the internal auditory canal and in the retrosigmoid area. Packing these cells with a variety of materials has been done but often indirectly, as visualization of all cells by the conventional operating microscopes may not be possible. Failure to recognize patent cells because of limited visualization may be an important cause of postoperative CSF leak. METHODS: This study compared CSF rhinorrhea rates of 38 consecutive suboccipital acoustic neuroma operations, in which conventional techniques were used to pack the temporal bone defect around the internal auditory canal, with the succeeding 24 consecutive operations, in which endoscopes were used to visualize all exposed air cells directly. After locating all patent air cells endoscopically, they were specifically sealed with bone wax, and then a small fat graft harvested from the wound margin was used to fill the remaining defect. RESULTS: Postoperative CSF rhinorrhea occurred in 7 of 38 (18.4%) operations in which no endoscopic technique was used and in 0 of 24 operations in which endoscopes were used. CONCLUSIONS: The use of endoscopes to visualize the temporal bone air cells that cannot be directly observed otherwise appears to reduce the incidence of postoperative CSF leak in suboccipital acoustic neuroma surgery.

Functional analysis of third ventriculostomy patency with phase-contrast MRI velocity measurements.

Our purpose was to explore the utility of cine phase-contrast MRI velocity measurements in determining the functional status of third ventriculostomies, and to correlate the quantitative velocity data with clinical follow-up. We examined six patients with third ventriculostomies and 12 normal subjects by phase-contrast MRI. The maximum craniocaudal to maximum caudocranial velocity range was measured at regions of interest near the third ventricular floor, and in cerebrospinal fluid anterior to the upper pons and spinal cord on midline sagittal images. Ratios of the velocities of both the third ventricle and prepontine space to the space anterior to the spinal cord were obtained. The velocities near the third ventricular floor and in the pontine cistern were significantly higher in patients than in normal subjects, but the velocity anterior to the spinal cord was similar between the groups. The velocity ratios, used to normalize individual differences, were also higher in patients than in controls. Two patients had lower velocity ratios than their fellows at the third ventricular floor and in the pontine cistern; one required a shunt 11 months later, while in the other, who had a third ventricular/thalamic tumor, the lower values probably reflect distortion of the third ventricular floor. We conclude that phase-contrast MR velocity measurements, specifically the velocity ratio between the high pontine cistern and the space anterior to the spinal cord, can help determine the functional status of third ventriculostomies.

Orbital hematic cyst: case report and clarification of terms.

We present a case of a hematic cyst and review the literature in order to clarify nomenclature discrepancies regarding terms used to describe cysts containing blood and blood breakdown products in and around the orbit. We believe orbital cysts containing blood and blood breakdown products should be separated into two major categories depending on the presence or absence of an epithelial or endothelial lining. A hemorrhage into a preexisting lesion such as a dermoid, on lymphangioma, which contains blood breakdown products lined by an endothelial or epithelial lining, should be referred to as an acute or chronic hematoma in a dermoid or lymphangioma. In contrast, a hematic cyst contains blood breakdown products and has no epithelial or endothelial lining but rather a fibrous pseudocapsule.

Microsurgical anatomy of the infratemporal fossa as viewed laterally and superiorly.

OBJECTIVE: Benign tumors involving cavernous sinus, trigeminal nerve, and middle cranial fossa occasionally extend to the infratemporal fossa (ITF). In this study, we describe the microsurgical anatomy and dissection of the ITF, as viewed laterally and superiorly. We also describe a new bypass graft to the supraclinoid internal carotid artery using the internal maxillary artery (IMA), which is found in the ITF. METHODS: Twelve cadaver specimens were used. Dissection required zygomatic arch osteotomy, downward displacement of the temporalis muscle, extensive subtemporal craniectomy, and mild elevation of the temporal lobe together with the dura. RESULTS: The anatomic relationships between the lateral and medial pterygoid muscles and the neurovascular bundle of the ITF are demonstrated. The neurovascular bundle contains the IMA, which runs horizontally, and the main branches of the mandibular nerve, which run vertically. The course and anatomic variations of the IMA and inferior alveolar, lingual, auriculotemporal, and buccal nerves are shown. The distal IMA was quite tortuous and, when the artery straightened, we were able to perform a tension-free in situ IMA graft to the supraclinoid carotid artery in 9 of 12 specimens. CONCLUSIONS: Knowledge of the anatomy of the ITF is a prerequisite for tumor resection in this area. The IMA may serve as a bypass graft to the supraclinoid internal carotid artery if the cavernous or petrous carotid artery is involved by tumor and needs to be sacrificed.

Anterior clinoid mucocele masquerading as retrobulbar neuritis.

Mucoceles arising from the anterior clinoid is rare. Although intrinsically benign, mucoceles in the sphenoid sinus (anterior clinoid variant) can lead to complications due to their proximity to other structures. We present a case of a young man whose visual complaints were typical for retrobulbar optic neuritis. Results of radiologic tests for diagnosis led us to the early detection of a surgically treatable condition, a sphenoid sinus mucocele (anterior clinoid variant). Early surgery was helpful in ameliorating the symptoms, leading to full recovery of visual function. The clinician should be aware of this rare entity with its presentation in a wide variety of signs and symptoms.

Cerebrospinal fluid flow waveforms: analysis in patients with Chiari I malformation by means of gated phase-contrast MR imaging velocity measurements.

PURPOSE: To determine the features of the cardiac cycle-related cerebrospinal fluid (CSF) flow pulsations in with Chiari I malformation before and after decompressive surgery. MATERIALS AND METHODS: Fifteen patients and 23 healthy subjects underwent cine phase-contrast magnetic resonance imaging. Ten patients were also examined after decompressive surgery. Four regions of interest were selected in the upper cervical subarachnoid space and premedullary cistern. Velocity and fraction of the cardiac cycle waveforms were plotted, and amplitude, temporal, and CSF displacement parameters were assessed. RESULTS: In the Chiari I patients, impaired systolic and unaltered diastolic CSF flow pulsations immediately below the foramen magnum were identified. After surgery, the systolic flow pulsations immediately below the foramen magnum improved. Good correlation with post-surgical improvement was observed. CONCLUSION: CSF flow waveform analysis helps demonstrate abnormalities in CSF flow at the foramen magnum and the benefits of decompressive surgery in patients with the Chiari I malformation.

Endovascular packing of carotid bifurcation aneurysm with polyester fiber-coated platinum coils in a rabbit model.

PURPOSE: To assess the value of endovascular packing of intracranial bifurcation aneurysms with commercially available coils. METHODS: Carotid bifurcation aneurysms were surgically created in 12 New Zealand rabbits with subsequent assessment of the extent of aneurysm ablation following endovascular packing with polyester fiber-coated platinum coils. RESULTS: Follow-up angiograms obtained from 29 to 108 days postprocedures showed various degrees of aneurysm ablation. Complete obliteration of aneurysm dome occurred in seven out of eight rabbits, while ablation of aneurysm neck was successful in only one out of eight. No spontaneous thrombosis was observed in seven control animals over a 3-month period. Coils of various configurations used in this experiment all maintained stable intraaneurysmal position. Histologic examination of treated aneurysms consistently demonstrated extensive proliferation of spindle cells on the coil surface and in interstices between coils with channels lined by cells resembling endothelial cells. Organized thrombus was not a prominent feature. CONCLUSION: Endovascular packing of human bifurcation aneurysms with current commercially available polyester fiber-coated platinum coils may not result in complete obliteration of the aneurysm with reendothelialization occurring across the aneurysm neck.

Aneurysm recurrence following endovascular balloon occlusion.

Endovascular balloon occlusion is an alternative treatment for surgically unclippable cerebral aneurysms. The results of aneurysm occlusion with either a silicone or a latex balloon in a common carotid artery bifurcation aneurysm model are compared to determine which type of balloon was least likely to result in aneurysm recurrence. Five rabbits each underwent endovascular balloon occlusion with either a silicone or a latex balloon, with seven rabbits serving as controls. At 3 months postocclusion, nine of the 10 balloon-treated aneurysms had recurred. The recurrent aneurysm tended to be larger in animals treated with silicone than with latex balloons. A dense fibrotic response was present around the collar of the latex balloons, but no significant fibrotic response was found in the silicone balloon group. This study suggests that with currently available balloons, the initial complete angiographic obliteration of an aneurysm following balloon occlusion should not be interpreted as a cure and that periodic follow-up angiography should be performed.

Flow dynamics in the human carotid artery: I. Preliminary observations using a transparent elastic model.

PURPOSE: We developed an elastic, transparent, life-size model of the cranial vessels that allowed us to visualize carotid artery flows directly, and wish to report our observations and recorded data. MATERIALS AND METHODS: The brachiocephalic arteries of 12 adult cadavers were cannulated and infused with acrylic. The heads were dissolved in alkali and, using a "lost wax" technique, a silicone model that reflected the shape and size of the original artery was produced. These models were connected to a closed circuit of flowing fluid. The fluid was rendered opaque by injecting isobaric dyes at various points in the streams. RESULTS: These dye opacified slipstreams showed a relatively low flow area visible in the posterior and lateral aspect of the carotid bulb that acted as an internal buffer, and directed the more posterior lateral slipstreams anteriorly and at the same time increased their velocity. The cervical internal carotid artery was relatively straight and showed flow patterns that were essentially laminar. In the petrous internal carotid artery, the dye-opacified slipstreams began a helical flow pattern, and areas of flow reversal became apparent along the inner aspect (lesser curvature) of the bend. The central slipstreams tended to flow in a straighter line, passing close to, and sometimes striking the wall of, the outer portion (greater curvature) of the bend. In the cavernous internal carotid artery, helical flow continued. The central slipstreams struck the outer surface (greater curve) of the arterial bend. The point that the central slipstream struck the wall was more distal during systole than during diastole. At the supraclinoid section laminar flow again became established. Certain slipstreams selectively entered individual cranial branches. CONCLUSION: The model we describe should allow more accurate study of complicated flow dynamics in vessels supplying the brain.

Enlargement of basilar artery aneurysms following balloon occlusion--"water-hammer effect". Report of two cases.

Two patients with distal basilar aneurysms were treated with intra-aneurysmal balloon occlusion. After apparently successful therapy, follow-up angiograms demonstrated aneurysm enlargement with balloon migration distally in the sac. Geometric mismatch between the base of the balloons and the aneurysm neck together with transmitted pulsation through the 2-hydroxyl-ethylmethacrylate (HEMA)-filled balloon directly contributed to aneurysm enlargement. In this report, the authors discuss the problems of progressive aneurysm enlargement due to a "water-hammer effect" and the possibility of hemorrhage following subtotal occlusion.