Airo® navigation versus freehand fluoroscopy technique: A comparative study of accuracy and radiological exposure for thoracolumbar screws placement.

PURPOSE: The aim was to compare the accuracy of freehand fluoroscopy and CT based navigation on thoracolumbar screws placement and their respective effects on radiological exposure to the patient. No previous study directly compared the Airo® navigation system to freehand technique. METHODS: In this monocentric retrospective study, 156 consecutive patients who underwent thoracolumbar spine surgery were included. Epidemiological data and surgical indications were noted. Heary classification was used for thoracic screws and Gertzbein-Robbins classification for lumbar screws. Radiological exposure was collected for each surgery. RESULTS: A total of 918 screws were implanted. We analyzed 725 lumbar screws (Airo® 287; freehand fluoroscopy 438) and 193 thoracic screws (Airo® 49; freehand fluoroscopy 144). Overall, lumbar screws accuracy (Gertzbein-Robbins grade A and B) was good in both groups (freehand fluoroscopy 91.3%; Airo® 97.6%; P<0.05). We found significantly less Grade B and C in the Airo® group. Thoracic accuracy was also good in both groups (Heary 1 and 2; freehand fluoroscopy 77.8%; Airo® 93.9%), without reaching statistical significance. Radiological exposure was significantly higher in the Airo® group with a mean effective dose of 9.69 mSv versus 0.71mSv for freehand fluoroscopy. CONCLUSION: Our study confirmed that the use of Airo® navigation yielded good accuracy. It however exposed the patient to higher radiological exposure compared with freehand fluoroscopy technique. LEVEL OF EVIDENCE: Level 3.

A case of intramuscular lumbar myxoma: Uncertainty in the preoperative diagnosis of a spinal soft tissue tumour.

We report an uncommon case of a 76-year-old woman who presented with lower back pain, an intermittent L5 radiculopathy and a right palpable paraspinal mass. Imaging studies revealed a 7-cm lumbar paraspinal pseudo-cystic soft tissue tumour developed in the paravertebral musculature, without a clear radiological diagnosis. Gross total surgical resection was performed, resulting in complete resolution of pain. Histopathological studies revealed an intramuscular (IM) myxoma. With a low positive predictive value of radiological work-up and a poor yield of percutaneous biopsies, surgery remains the mainstay treatment for these rare soft tissue tumours of the lumbar spine. Intramuscular myxomas show excellent postoperative results.

Lumboperitoneal shunt for treatment of dural ectasia in ankylosing spondylitis.

Neurological complications of ankylosing spondylitis (AS) are reported in 2.1% of patients. Cauda equina syndrome (CES) is rare and occurs at the ankylosing stage. MRI and CT of the lumbar spine show a cauda equina deformation with dural ectasia and bony erosion. We report three patients with AS presenting with progressive CES. These patients underwent lumboperitoneal shunting (LPS) surgery. The motor deficit improved in all cases. We suggest that CES develops from arterial pulsation of the CSF on a dural sac with reduced elasticity and that LPS reduces these intradural pressure shock waves. A meta-analysis by Ahn et al. [Ahn NU, Ahn UM, Nallamshetty L, et al. Cauda equina syndrome in ankylosing spondylitis (the CES-AS syndrome): meta-analysis of outcomes after medical and surgical treatments. J Spinal Disord 2001;14:427-33] concludes that surgical treatment has a better outcome than conservative or no treatment. Adding our 3 patients to this analysis, it appears that LPS for CES in AS is more efficient than laminectomy. LPS is a routine procedure for a rare indication, which promises improvement or atleast a stabilization of this disabling evolution of the disease.

[CT and MRI features of arachnoid cyst of the petrous apex: report of 3 cases]. / Aspects TDM et IRM du kyste arachnoïdien de l'apex pétreux.

PURPOSE: To describe the CT and MRI features of 3 cases of arachnoid cyst of the petrous apex. PATIENTS AND METHODS: Three patients with isolated trigeminal neuralgia, trigeminal hypoesthesia, and sinusitis. Axial and coronal CT images were obtained. T1W, FSE T2W, FLAIR, T2*W and diffusion-weighted MR sequences were obtained. RESULTS: In all cases, both CT and MRI showed expansile lesions eroding the petrous apex. Lesions were hypodense on CT and isointense to CSF on MRI, without contrast enhancement. In one case, the lesion was contiguous with Meckel's cave with temporal fossa and sphenoid sinus extension. CT and MR imaging features are useful to distinguish arachnoid cysts of the petrous apex from other benign lesions of the petrous apex. CONCLUSION: CT and MRI imaging features allow diagnosis of arachnoid cyst of the petrous apex because its imaging features, especially on DWI, are different from other cystic lesions of the petrous apex, namely cholesteatoma. It should be considered in patients with trigeminal involvement, especially trigeminal neuralgia.

Atlantoaxial rotatory subluxation with ankylosis in an 11-year-old girl: a case report.

STUDY DESIGN: Report of an 11-year-old girl with a left atlantoaxial rotatory subluxation and ankylosis found 20 months after she sustained a cervical injury. OBJECTIVE: To describe the radiographic characteristics of this rare deformity assessed with a combination of spiral CT scan with multiplanar three-dimensional reformations and functional CT scan. SUMMARY OF BACKGROUND DATA: Atlantoaxial rotatory subluxation is a well-known condition, but its association with lateral C1-C2 ankylosis has not been reported to our knowledge. METHODS: For a complete assessment of the dislocation, a combined morphologic volumetric and functional CT study was performed. RESULTS: Spiral CT showed an atlantoaxial rotatory subluxation with lateral C1-C2 ankylosis. CT study also demonstrated a lateral C1-C2 subluxation and an ipsilateral occipitoatlantal subluxation. Cervical MRI showed no spinal cord compression despite the seriousness of the dislocation process. CONCLUSIONS: Whereas "classic" spiral study with multiplanar and three-dimensional reformations allows precise assessment of relationships between the upper cervical vertebrae, as well as bony changes, a functional CT study is essential for cervical biomechanic assessment of rotational instabilities of the craniovertebral junction and upper cervical spine.

[Vascular complications after acoustic neurinoma surgery]. / Complications vasculaires apres chirurgie du neurinome de l'acoustique.

OBJECTIVE: To report six cases of vascular complications occurring after acoustic neuroma surgery and to discuss the postoperative signs and symptoms that should alert the surgeon, in order to undertake the appropriate treatment as soon as possible. METHODS: Four hundred thirty-two cases of acoustic tumors operated by the same surgeons between January 1991 and December 2000 were reviewed. RESULTS: Six cases of vascular complications were identified: one case of cerebral vasospasm secondary to persistence of subarachnoid blood after injury to Dandy's vein; three cases of arterial infarction giving rise to a partial anterior inferior cerebellar artery (AICA) syndrome with an unusual nystagmus in two cases (ipsilateral in one patient and strong controlateral in one patient presenting preoperative vestibular areflexia); one case of hematoma of the cerebello-pontine angle (CPA) causing strong ipsilateral nystagmus; and one case of venous infarction of the cerebellar vermis secondary to accidental sinus thrombosis. CONCLUSIONS: Vascular complications after acoustic neuroma surgery are potentially devastating and should be identified as early as possible. Rapid extubation is recommended for systematic neurologic assessment. Among abnormal signs and symptoms that should alert the surgeon, marked nystagmus ipsilateral to the operated side or contralateral in patient presenting preoperative vestibular areflexia appears to be of great value.

Reversible leukoencephalopathy in cerebral amyloid angiopathy presenting as subacute dementia.

This report concerns a 71-year-old woman who had rapid progressive dementia along with myocloni and increased blood pressure. Cranial computed tomography and magnetic resonance imaging scans showed bilateral widespread white matter changes with mass effect. A brain biopsy revealed an amyloid angiopathy in leptomeningeal as well as cerebral cortex arteries. After 2 months of antihypertensive treatment, a dramatic improvement of cognitive functions and a spectacular regression of leukoencephalopathy were observed. We suggest that hypertensive encephalopathy may worsen or reveal cerebral amyloid angiopathy.

[Contribution and Cost-Effectiveness of ABR and MRI in Acoustic Neuroma screening. Retrospective Study of 151 Cases]. / Intérêt et rapport coût efficacité des PEA et de l'IRM dans le dépistage du neurinome de l'acoustique.

The aim of this study was to retrospectively assess during two periods (1991-1995 and 1996-2000) if MRI spreading had changed: (1) private ENT physicians screening habits; (2) the average tumor size at the time of diagnosis and the diagnostic delay of acoustic neuroma; and (3) the cost of acoustic neuroma diagnosis. In addition, the sensibility of each diagnostic test was calculated on 151 tumors. Our results show no significant change neither in the screening strategy (except a mild decrease in CT-scan utilization) nor in the tumor size, diagnostic delay or diagnostic cost between the two periods. Even if MRI is the gold standard for acoustic neuroma diagnosis, our 86%-sensibility of ABR, increased to 99% if combined with stapedial reflex and caloric test may still incline to use ABR in selected cases.

[Hearing preservation in vestibular schwannoma surgery: indications, techniques and results in the literature since 1990]. / La préservation de l'audition au cours de la chirurgie du neurinome de l'acoustique. Indications, techniques et résultats de la littérature depuis 1990.

Many authors have recently reported hearing preservation for approximately two-thirds of acoustic neuroma patients. The results have driven them to recommend early surgery for all patients whose hearing might be saved. Inversely, other authors advocate that MRI-screening may be beneficial in some patients and suggest surgery only in case of tumor growth or progressive hearing loss. In order to facilitate therapeutic decision making, we reviewed the techniques and results in the main papers dealing with hearing preservation in the course of acoustic neuroma surgery published since 1990. This analysis showed that the average percentage of useful hearing preservation is about 31%. It is however difficult to compare the different series due to the different methodologies used. This emphasizes the need for standardization of hearing selection and reporting criteria to a) identify factors predictive of success (tumor characteristics, preoperative hearing, monitoring, surgical pathways), and b) elaborate well accepted decisional guidelines (early surgery or MRI screening), notably for small and non-symptomatic tumors which show increasing prevalence.

[Unusual preseptal location of an orbital cavernous hemangioma in African patient]. / Localisation inhabituelle préseptale d'un hémangiome caverneux orbitaire chez une patiente d'origine africaine.

Cavernous hemangioma is the most common primary vascular orbital tumor in adults. Generally the benign tumor arises within the muscle cone, revealed by proptosis with choroidal folds, and more rarely develops in other orbital localizations. We report the case of a 42-year-old female African patient who had a cavernous hemangioma in an unusual anterior localization. Clinically, a small superficial tumor was palpated in the right superior nasal orbital angle. After complete surgical excision, the histopathological study established the diagnosis of cavernous hemangioma

[Residual left orbital phlebolith. An anatomic-clinical observation]. / Phlébolithe résiduelle orbitaire gauche. A propos d'une observation anatomo-clinique.

A 29-year-old female patient displayed a dense and hard left orbital mass, inferiorly, 3 years after she was treated through a neurosurgical approach for a left orbital varix. The lesion was hyperdense on CT-scan and was removed through a trans-conjunctival approach, with an excellent result. The histological diagnosis was a phlebolith.

[Interest of free flaps for cranial base reconstruction]. / Intérêt des lambeaux libres dans la reconstruction de la base du crâne.

We describe our experience in treating 7 patients who underwent skull base reconstruction with free flap (6 latissimus dorsi, 1 rectus abdominis) between October 1996 and November 1998. Four patients underwent temporal bone resection with auricular resection, 2 patients underwent anterior and middle cranial fossa resection, 1 patient underwent frontotemporal resection. There have been no failures of the free flaps and one cerebrospinal fluid leak. We advocate free flap reconstruction after temporal bone resection with auricular resection, and after anterior or middle cranial fossa resection when local flap options are not available or with complex dead space.

Spinal melanotic schwannoma: a tumour with poor prognosis.

AIM: To clarify the prognosis of melanotic schwannoma. This is a rare tumour which is generally considered as a benign lesion, reported in many cases with a short follow-up only. METHODS AND RESULTS: Five cases of spinal melanotic schwannoma were retrospectively studied. The tumours were examined using standard histological, immunohistochemical and ultrastructural methods. No features of malignancy (high mitotic count, atypia or necrosis) were found in the primary tumours. The follow-up period ranged from 3 to 7 years. Malignant clinical behaviour was clear-cut in four cases: three patients died from metastases to various sites and one presented several discrete spinal tumours of the same type seven years after the first operation. Only one patient presented no recurrence and was free of disease 6 years after initial diagnosis. The review of 57 cases of the literature (including our cases), showed that 15% of the cases had recurrences and 26.3% were complicated by metastasis. Only 53% of the cases followed for more than 5 years, were free of disease vs. 67.5% of the cases with shorter follow-up. Twenty additional cases had no follow-up. CONCLUSION: Appropriate long-term follow-up is required for all melanotic schwannomas, as it may recur or metastasize after more than 5 years, even in the absence of overt malignant histological features.

Surgical treatment of dumbbell neurinomas of the cervical spine.

Cervical neurinomas ex-tending through the intervertebral foramen are uncommon. They raise difficult problems of surgical management. The few papers dealing with surgical technique for removal of these tumors are reviewed. The surgical approach has to be chosen from posterior, anterior, and anterolateral routes. Analysis is essentially devoted to the radicality of tumor resection, nerve root preservation, relation to the vertebral artery, and compromise of spinal stability.

Intramedullary cavernous angioma. Resection by oblique corpectomy.

BACKGROUND: Intramedullary cavernomas are rare lesions usually operated on via a posterior approach and myelotomy. CASE REPORT: A 42-year-old woman progressively developed a tetraplegia with sphincter disturbances over a period of 26 years. Magnetic resonance imaging showed a cervical intramedullary cavernoma with an extramedullary anterolateral exophytic portion. To avoid myelotomy, this lesion was approached directly via its anterior exophytic portion. Through a cervical anterolateral approach, the vertebral body of C4 and the intervertebral discs were obliquely drilled out. The posterior longitudinal ligament and the dura mater were opened. The exophytic portion was coagulated and the intramedullary portion was completely excised. The dura mater was closed and a bone graft was inserted between C3 and C5 and secured with a plate. RESULTS: After transient worsening, upper limb weakness improved from its preoperative status but paraparesis persisted after a follow-up of 12 months. The sphincter disturbances disappeared. CONCLUSIONS: The anterolateral approach combined with oblique corpectomy may be an appropriate technique in case of anterior intramedullary cavernomas. It provides direct access to the lesion, avoiding additional myelotomy.

The extent of drilling in lateral approaches to the cranio-cervical junction area from a series of 125 cases.

The trans-condylar approach to the craniocervical junction area (CCJA) requires a more or less extensive drilling of the two first cervical joints (C0-C1 and C1-C2). The extent of drilling necessary to resect a lesion at the CCJA was analyzed from a series of 125 cases including 114 tumours and 11 non-tumoural processes treated using a lateral approach (postero-lateral or antero-lateral) over a 15-year period (1980-1995). The extent of drilling was estimated on CT scanner axial views from the reduction of the joints surface and three groups were determined: A/less than one third B/between one third and one half, and C/more than one half. The extent of drilling was compared with the lesion location in relation to the bone limits of the CCJA: within these limits, outside them and into the bony structures. It was also analyzed with regard to pathology when separated into three groups non-osseous tumours, osseous tumours and chordomas, and non tumoural processes. Only 26 cases had a significant drilling, i.e., more than one third of the joint surfaces and of these, 14 were more than one half. In all these 14 cases, the bone structures were already invaded and 13 of them were, to some extent, beyond the bone limits of the CCJA. Of the 12 cases with drilling between one third and one half, 11 involved the bone structures and 1 was located inside the CCJA bone limits. Drilling of more than one third was required only in the case of bone lesions: 10 out of 23 bone tumours, all the 14 cases of chordomas, one case of rheumatoid arthritis and one case of C1-C2 joint spondylosis. In the other cases including mostly non-osseous tumours, drilling was limited to less than one third, though a high rate of complete removal was achieved (98%). Stabilization by arthrodesis with posterior grafting (N = 10) or by lateral bone grafting (N = 5) was achieved in all cases involving more than one half drilling, and in one case of tuberculosis. By adequately choosing the surgical approach, the extent of drilling can always be minimal. Extensive bone resection is only necessary when the tumour has already destroyed the joints. In that case, lateral or posterior fusion is an efficient technique.

Failure of third ventriculostomy in the treatment of aqueductal stenosis in children.

OBJECT: The goal of this study was to analyze the types of failure and long-term efficacy of third ventriculostomy in children. METHODS: The authors retrospectively analyzed clinical data obtained in 213 children affected by obstructive triventricular hydrocephalus who were treated by third ventriculostomy between 1973 and 1997. There were 120 boys and 93 girls. The causes of the hydrocephalus included: aqueductal stenosis in 126 cases; toxoplasmosis in 23 cases, pineal, mesencephalic, or tectal tumor in 42 cases; and other causes in 22 cases. In 94 cases, the procedure was performed using ventriculographic guidance (Group I) and in 119 cases by using endoscopic guidance (Group II). In 19 cases (12 in Group I and seven in Group II) failure was related to the surgical technique. Three deaths related to the technique were observed in Group I. For the remaining patients, Kaplan-Meier survival analysis showed a functioning third ventriculostomy rate of 72% at 6 years with a mean follow-up period of 45.5 months (range 4 days-17 years). No significant differences were found during long-term follow up between the two groups. In Group I, a significantly higher failure rate was seen in children younger than 6 months of age, but this difference was not observed in Group II. Thirty-eight patients required reoperation (21 in Group I and 17 in Group II) because of persistent or recurrent intracranial hypertension. In 29 patients shunt placement was necessary. In nine patients in whom there was radiologically confirmed obstruction of the stoma, the third ventriculostomy was repeated; this was successful in seven cases. Cine phase-contrast (PC) magnetic resonance (MR) imaging studies were performed in 15 patients in Group I at least 10 years after they had undergone third ventriculostomy (range 10-17 years, median 14.3 years); this confirmed long-term patency of the stoma in all cases. CONCLUSIONS: Third ventriculostomy effectively controls obstructive triventricular hydrocephalus in more than 70% of children and should be preferred to placement of extracranial cerebrospinal shunts in this group of patients. When performed using ventriculographic guidance, the technique has a higher mortality rate and a higher failure rate in children younger than 6 months of age and is, therefore, no longer preferred. When third ventriculostomy is performed using endoscopic guidance, the same long-term results are achieved in children younger than 6 months of age as in older children and, thus, patient age should no longer be considered as a contraindication to using the technique. Delayed failures are usually secondary to obstruction of the stoma and often can be managed by repeating the procedure. Midline sagittal T2-weighted MR imaging sequences combined with cine PC MR imaging flow measurements provide a reliable tool for diagnosis of aqueductal stenosis and for ascertaining the patency of the stoma during follow-up evaluation.

Transnasal endoscopic removal of an orbital cavernoma.

The approach to posterior and medial orbital tumors is still a challenge, since poor functional results are frequent. We report a case of cavernoma successfully removed by a modified transnasal endoscopic procedure. The patient, a 56-year-old woman, complained of a decrease in vision of the left eye. Magnetic resonance imaging evidenced a lesion in the posterior part of the orbital cavity, inferior to the optic nerve, extending to the sphenoidal cleft. The lesion was isodense on T1-weighted images and showed contrast enhancement. Because of the medial location of the tumor, the patient was referred to the otolaryngology department by the neurosurgeons, and a transnasal endoscopic approach was chosen. A large exposure of the operative field was obtained, and a cavernoma was removed. Rapid relief of the symptoms was obtained. In view of this good result, we advocate the transnasal endoscopic approach in cases of inferomedial and posterior intraconal lesions as an alternative and addition to the standard techniques of orbital surgery.

Sylvian aqueduct syndrome and global rostral midbrain dysfunction associated with shunt malfunction.

OBJECT: This study is a retrospective analysis of clinical data obtained in 28 patients affected by obstructive hydrocephalus who presented with signs of midbrain dysfunction during episodes of shunt malfunction. METHODS: All patients presented with an upward gaze palsy, sometimes associated with other signs of oculomotor dysfunction. In seven cases the ocular signs remained isolated and resolved rapidly after shunt revision. In 21 cases the ocular signs were variably associated with other clinical manifestations such as pyramidal and extrapyramidal deficits, memory disturbances, mutism, or alterations in consciousness. Resolution of these symptoms after shunt revision was usually slow. In four cases a transient paradoxical aggravation was observed at the time of shunt revision. In 11 cases ventriculocistemostomy allowed resolution of the symptoms and withdrawal of the shunt. Simultaneous supratentorial and infratentorial intracranial pressure recordings performed in seven of the patients showed a pressure gradient between the supratentorial and infratentorial compartments, with a higher supratentorial pressure before shunt revision. Inversion of this pressure gradient was observed after shunt revision and resolution of the gradient was observed in one case after third ventriculostomy. In six recent cases, a focal midbrain hyperintensity was evidenced on T2-weighted magnetic resonance imaging sequences at the time of shunt malfunction. This rapidly resolved after the patient underwent third ventriculostomy. CONCLUSIONS: It is probable that in obstructive hydrocephalus, at the time of shunt malfunction, the development of a transtentorial pressure gradient could initially induce a functional impairment of the upper midbrain, inducing upward gaze palsy. The persistence of the gradient could lead to a global dysfunction of the upper midbrain. Third ventriculostomy contributes to equalization of cerebrospinal fluid pressure across the tentorium by restoring free communication between the infratentorial and supratentorial compartments, resulting in resolution of the patient's clinical symptoms.