Comparing nonrigid registration techniques for motion corrected MR prostate diffusion imaging.

PURPOSE: T2-weighted magnetic resonance imaging (MRI) is commonly used for anatomical visualization in the pelvis area, such as the prostate, with high soft-tissue contrast. MRI can also provide functional information such as diffusion-weighted imaging (DWI) which depicts the molecular diffusion processes in biological tissues. The combination of anatomical and functional imaging techniques is widely used in oncology, e.g., for prostate cancer diagnosis and staging. However, acquisition-specific distortions as well as physiological motion lead to misalignments between T2 and DWI and consequently to a reduced diagnostic value. Image registration algorithms are commonly employed to correct for such misalignment. METHODS: The authors compare the performance of five state-of-the-art nonrigid image registration techniques for accurate image fusion of DWI with T2. RESULTS: Image data of 20 prostate patients with cancerous lesions or cysts were acquired. All registration algorithms were validated using intensity-based as well as landmark-based techniques. CONCLUSIONS: The authors' results show that the "fast elastic image registration" provides most accurate results with a target registration error of 1.07 ± 0.41 mm at minimum execution times of 11 ± 1 s.

Assessment of left ventricular function parameters with a new three-dimensional shape model.

PURPOSE: To evaluate a 3D model of the left ventricle (LV) which allows calculation of LV function parameters on the basis of both short axis (SA) and long axis (LA) cine acquisitions. Comparison with the conventional Simpson's rule method in a volunteer and patient collective. MATERIALS AND METHODS: Cine imaging was performed with a prospectively triggered SSFP sequence: trueFISP: TR 3.6 msec, TE 1.8 msec, bFFE: TR 3.0 msec, TE 1.4 msec, flip angle 60 degrees , resolution 1.37 x 1.37 mm, slice thickness 8 mm, gap 2 mm in SA orientation from apex to basis and in radial LA orientation (spacing 15 degrees) in 11 volunteers and 27 patients with mitral valve insufficiency. Five different volume computations were compared: Simpson's rule based on all SA slices (M0), 3D shape model based on all SA slices (M1a), 3D shape model based on 3 SA slices (M1b), 3D shape model based on all SA and LA slices (M2a), and 3D shape model based on 3 SA slices and 1 LA slice (M2b). RESULTS: M 0 and M 1a give similar results (r: 0.99, b: 0.98). M 2a produces larger volumes than M 0 (b: 0.85) due to the inclusion of the LA contours. M 1b effectively reproduces the volumes computed with M 0 (r: 0.99, b: 1.02). M 2b effectively reproduces the volumes computed with M 2a (r: 0.99, b: 0.94). M 2b and M 0 give similar results in the patient collective (r: 0.99, b: 0.97). CONCLUSION: The proposed 3D shape model allows merging of information acquired in different orientations and thus the combination of SA and LA contours with better coverage of the left ventricle. It provides a suitable fit with a reduced number of segmented contours.

Mechanical supplementation by non-rigid fixation in degenerative intervertebral lumbar segments: the Wallis system.

A first-generation implant for non-rigid stabilization of lumbar segments was developed in 1986. It included a titanium interspinous blocker and an artificial ligament made of dacron. Following an initial observational study in 1988 and a prospective controlled study from 1988 to 1993, more than 300 patients have been treated for degenerative lesions with this type of implant with clinical and mechanical follow-up. After careful analysis of the points that could be improved, a second-generation implant called the "Wallis" implant, was developed. This interspinous blocker, which was made of metal in the preliminary version, is made of PEEK (polyetheretherketone) in the new model. The overall implant constitutes a "floating" system, with no permanent fixation in the vertebral bone, to avoid the risk of loosening. It achieves an increase in the rigidity of destabilized segments beyond normal values. The clinical trials of the first-generation implant provided evidence that the interspinous system of non-rigid stabilization is efficacious against low-back pain due to degenerative instability and free of serious complications. The first-generation devices achieved marked, significant resolution of residual low-back pain. These results warrant confirmation. A randomized clinical trial and an observational study of the new implant are currently underway. Non-rigid fixation clearly appears to be a useful technique in the management of initial forms of degenerative intervertebral lumbar disc disease. This method should rapidly assume a specific role along with total disc prostheses in the new step-wise surgical strategy to obviate definitive fusion of degenerative intervertebral segments. At present, the Wallis system is recommended for lumbar disc disease in the following indications: (i) discectomy for massive herniated disc leading to substantial loss of disc material, (ii) a second discectomy for recurrence of herniated disc, (iii) discectomy for herniation of a transitional disc with sacralization of L5, (iv) degenerative disc disease at a level adjacent to a previous fusion, and (v) isolated Modic I lesion leading to chronic low-back pain.

[Postoperative compressive spinal epidural hematomas. 15 cases and a review of the literature]. / Hématorrachis ou hématome extradural rachidien (HER) postopératoire compressif. Etude de 15 cas et revue de la littérature.

PURPOSE OF THE STUDY: In the literature, the frequency of postoperative compressive spinal epidural hematomas (SEH) appearing very low, we conducted the present study to determine the frequency of this complication in their unit and look for causative and predisposing factors. MATERIAL AND METHODS: Among the 1,487 spinal operations performed in our unit between September 1997 and August 1998, fifteen patients had postoperative compressive SEH; their files were retrospectively analyzed regarding the initial intervention, postoperative period, revision operation and neurologic follow-up. RESULTS: Five women and ten men were involved ranging in age from 47 to 70 years (average, 59.5 years). The primary intervention concerned the cervical spine in one case, the thoracic spine in seven and the lumbar spine in seven. Ten of the fifteen cases including all seven of the thoracic SEH (performed for compressive metastatic epiduritis) involved a laminectomy. A stenotic canal was the indication for the primary intervention in six of the seven lumbar cases. The average delay before onset of symptoms was 1.5 hours, 3.7 hours, and 5.3 hours after the cervical, thoracic, and lumbar interventions, respectively. The clinical pattern began with segmental pain rapidly followed first by bilateral radicular sensory deficit, then unilateral or bilateral motor deficit, except in the patients with thoracic SEH in whom segmental pain was followed by signs of cord impingement. Excluding the four cases in which diagnosis was retarded by work-up examinations (3 cases) or a misleading picture (1 case), revision surgery was performed from 1.25 to 4 hours after onset of symptoms (average, 2.75 hours). In the patients for whom reoperation was delayed, SEH resulted in permanent complete paralysis or sphincter dysfunction. In contrast, eight of the ten patients who were reoperated within four hours of the onset of symptoms either recovered completely or recovered their former neurologic status. DISCUSSION: Compressive SEH after spinal surgery is rare, only 41 cases having been reported aside from the series of Deburge et al. In the literature, the frequency is around 1 to 2 for 1000 operations for some authors, as opposed to 3 p. 100 and 6 p. 100 found by two other groups. The 1 p. 100 of the present series is close to the latter values. Nonetheless, it is probably important to take the type of surgery into account, as shown by the current series in which SEH occurred after 5.9 p. 100 of the operations for metastasis, but only once out of 304 anterior cervical interventions. To reduce the risk as much as possible, it is important to be aware of the factors that may contribute to this complication. Several recommendations concerning prevention of SEH are thus discussed. Once SEH has occurred, the only modifiable prognostic factor appears to be the delay before reintervention. CONCLUSION: Although postoperative SEH is relatively rare, it may have dramatic consequences. In our opinion, reintervention must be performed as soon as possible after the onset of neurologic deficit, the work-up investigations only prolonging the critical surgical delay, which is probably the only alterable prognostic factor.

[Thoracoscopy versus thoracotomy in spinal surgery: comparison of 2 paired series]. / Thoracoscopie versus thoracotomie en chirurgie rachidienne: comparaison de deux séries appariées.

PURPOSE OF THE STUDY: This study was carried out to compare the intraoperative and postoperative results of conventional surgery of the thoracic spine by thoracotomy with those of the thoracoscopic technique to determine the advantages of this new approach. MATERIAL AND METHODS: A series of twenty-nine patients operated by thoracoscopy for a spinal disorder was matched regarding the etiology of spine disease and type of surgical procedure with twenty-four patients operated by thoracotomy. This matching procedure yielded two similar groups of twenty patients. The criteria used for evaluation were the duration of the procedure, blood loss, intraoperative complications, the duration of stay in postoperative intensive care, the duration and yield of pleural drainage, the time until return to the upright position, duration of use of WHO grade-three analgesics (morphine derivatives), the postoperative complications, and the length of hospitalization. RESULTS: There was a significant difference in three parameters: the duration of the procedure (thoracotomy, 172 min; thoracoscopy, 246 min; p < 0.006), intraoperative bleeding (thoracotomy, 837 mL; thoracoscopy, 447 mL; p < 0.0009), and duration of use of WHO grade-three analgesics (thoracotomy, 4.5 days; thoracoscopy, 2.3 days; p = 0.011). There was no difference in the intra- or postoperative complication rates of the two methods. DISCUSSION: The better view provided by thoracoscopy and its preservation of the wall structures probably explain why there was less bleeding and postoperative pain with this technique. The insufficiency of the current thoracoscopic instrumentation and the learning curve account for the longer duration of these interventions. CONCLUSION: These data confirm the usefulness of thoracoscopy which is less traumatizing, less hemorrhagic, and causes no more complications than thoracotomy. The longer operative duration is currently a minor drawback, and should shorten with experience and the development of specific instrumentation.

Age-related changes in the cervical spines of front-line rugby players.

Cervical spine trauma occurs frequently in front-line rugby players. To evaluate the accumulative effects of this trauma, magnetic resonance imaging scans of the cervical spine were performed on 47 rugby players and 40 age-matched control subjects. The aim of this study was to compare the changes in the cervical spine of players at different points in their careers. A study of cervical spine changes, including spinal curve, spinal constituents, posttraumatic deformities, and degenerative modifications, was completed by a study of cervical measurements. Front-line rugby players showed more early degenerative alterations on magnetic resonance imaging scans than did the control subjects of the same age. These changes correlated with age and were probably linked with repetitive cervical trauma throughout the players' careers. Particular attention should be paid to the data confirming cervical spine canal stenosis in front-line players, which may place these athletes at risk for acute neurapraxia while playing this collision sport.

[A prospective study of ENT complication following surgery of the cervical spine by the anterior approach (preliminary results)]. / Etude prospective des complications ORL de la chirurgie du rachis cervical par voie antérieure (résultats préliminaires).

In order to evaluate complications due to cervical spine surgery using the anterior cervical approach a prospective study was conducted on 125 patients. ENT examination with the fibroscope was employed for all the patients before the procedure. The patients were operated on under general anesthesia and were intubated with an armoured tube, and then were placed in an intensive care unit for 24 hours. Assessment of deglutition and an ENT examination were performed the day after surgery. Before surgery, two cases of vocal cord paralysis were noted. 111 patients (88.8%) presented with subjective disorders: problems such as sore throat, odynophagia, dysphagia, dysphagia with overspill and hoarseness were respectively noted in 55 (44%), 34 (27.2%), 32 (25.6%), 11 (8.8%) and 13 (10.4%) cases. Dyspnoea was found in 2 cases (1.6%). 117 patients (93.6%) presented postoperative anomalies which were found on the posterolateral pharyngeal wall, on the arytenoids and on posterior third of the vocal cords. Inflammatory and/or swollen lesions were slight, moderate, significant or very significant in respectively 22.4%, 22.4%, 15.2% and 1.6% of cases. Very significant circumferential swelling of the pharyngeal wall and of the arytenoids was responsible for two cases of respiratory distress, and the patients required reintubation and return to theatre. Severe pharyngeal lesion correlated with duration of surgery (r = 0.20; p < 0.05), with the number levels of fusion (r = 0.02; p < 0.02) and with the age of the patient (p < 0.02). Six patients presented problems of mobility of the vocal cords: 3 had a right vocal cord paresis which was temporary and 3 had paralysis, also on the right but which persisted. There were no other complications. It is concluded that (i) ENT complications are frequently found in postoperative cervical spine surgery using the anterior cervical approach, some of them being severe. An ENT examination must be performed before the procedure for legal reasons. It is also recommended in the postoperative period in the case of discomfort; (ii) patients need to be placed in an intensive care unit during for the first 24 hours (iii). This study needs to be attended over more patients (iv) comparison with a control group of patients having non cervical surgery and intubated in the same way is needed to differentiate lesions related to surgery or intubation.

Reduction technique for uni- and biarticular dislocations of the lower cervical spine.

STUDY DESIGN: A technical report concerning the methods of reduction of dislocations of the lower cervical spine used in 168 consecutive cases (77 unilateral and 91 bilateral dislocations). OBJECTIVES: To evaluate the efficacy of a reduction protocol comprising three successive phases: reduction by traction, reduction by closed maneuvers with the patient under general anesthesia, and open reduction. SUMMARY OF BACKGROUND DATA: Management of cervical dislocations varies greatly among spine treatment centers, especially concerning the upper limit of traction, the safety of closed manipulations in anesthetized patients, and the approach preferred when surgical reduction is necessary. METHODS: Reduction by gradual traction without anesthesia was attempted first. In case of failure, specific closed manipulations were used with the patient under general anesthesia just before anterior arthrodesis was performed. If this failed, anterior surgical reduction was attempted. Anterior fusion was performed in every patient, even when closed reduction was successful, because of the lasting instability produced by attending ligamentous lesions. RESULTS: Of the patients in 168 cases of dislocation, the protocol failed in 5, all of whom had longstanding unilateral dislocation. Of the 91 with bilateral dislocation, reduction was achieved by simple traction in 39 (43%), by maneuvers with the patient under general anesthesia in 27 (30%), and by anterior surgery in 25 (27%). Among the patients in 77 cases of unilateral dislocation, reduction was achieved by traction in 18 (23%), by external maneuvers in 28 (36%), and by anterior surgery in 26 (34%). In 7 patients, discal herniation engendering neurologic signs was resected during anterior surgery. No neurologic deterioration during or immediately after reduction by this protocol was observed. CONCLUSIONS: This protocol consists of application of rapidly progressive traction, followed if necessary by one or two reduction maneuvers with the patient under general anesthesia. If both methods fail, specific surgical procedures using an anterior exposure seem to be reliable, in that anatomic reduction was obtained in 163 of 168 patients without neurologic deterioration.

Periganglionic foraminal steroid injections performed under CT control.

PURPOSE: The purpose of our study was to evaluate the efficacy of direct intraforaminal steroid injections into the periganglionic space in the treatment of radicular pain. METHODS: Periganglionic infiltrations were performed in 41 patients with acute or chronic radicular pain. Neuroradiologic imaging in all patients showed foraminal stenosis due to degenerative disorders or herniated disk. All injections were performed under CT control. RESULTS: Seventy percent of patients had significant pain reduction, with the greatest success (90% of patients) in those whose foraminal stenosis was due to degenerative disorders; 45% of patients with foraminal herniated disks had pain relief. CONCLUSION: Intraforaminal steroid injection is useful in the treatment of radicular pain, particularly in cases of foraminal degenerative stenosis.

Complications of vertebral metastasis surgery.

The authors report their experience concerning complications of spinal metastasis surgery. The purpose of this study was to assess the frequency of such complications and analyse the factors influencing their occurrence. The records of 145 patients treated between 1982 and 1991 for metastatic disease of the spine were retrospectively reviewed for intra- and postoperative complications. Other factors such as radiation therapy, emergent nature of surgery, and neurologic deficits were analysed for potential correlations with the frequency of complications. Twenty-seven (18.6%) patients developed postoperative complications. Wound dehiscence and infection (11%) were the most frequent complications. Statistical analysis showed a significant influence of three factors: preoperative radiation therapy, paraplegia before surgery, and surgery under emergency conditions. The rate of complications in this surgery is lower than might be expected and can be significantly reduced. Surgery should be performed before radiation therapy and before appearance of substantial neurologic deficits.

[Thoracolumbar fractures. Pathomorphology and indications for treatment]. / Les fractures du rachis thoraco-lombaire patho-morphologie et indications thérapeutiques.

The indications for conservative and surgical management of fractures of the thoracolumbar spine are reviewed, based upon the morphology of the lesions, which is assessed by meticulous analysis of radiographs, CT scan and in some cases MRI. The author advocates using the AO classification, which considers several subtypes of fractures: compression fractures, distraction fractures and fractures with multidirectional displacement. The indication for treatment is based upon morphological analysis of the lesions, while other factors such as the general condition of the patient or the locally available surgical environment must also be taken into consideration. Up to 50% of thoracolumbar fractures can benefit from surgical management, with posterior or anterior stabilisation, the latter performed through thorascoscopy in selected cases.

A novel paraspinal surgical approach for lumbar lateral extraforaminal root entrapment.

We describe a new surgical route that we call the "crest approach" for treating extraforaminal disc herniation in the lumbar spine. This approach is useful only for the levels above L5-S1. It permits perfect root decompression without any bony resection that would contribute to instability. Muscle retraction and devascularization are reduced. Risk of nerve root lesions is minimal since the herniation is removed before root mobilization. Fifteen patients have been treated using this procedure. In all 15, pain and/or neurologic deficits remitted rapidly with no postoperative complications. In conclusion, the crest approach provides highly satisfactory operating conditions by simplifying exposure and greatly limiting the risk of complications. In our relatively limited experience using this procedure, only satisfactory results have been observed.

[Sagittal balance of the spine]. / L'équilibre rachidien dans le plan sagittal.

PURPOSE OF THE STUDY: The authors examined the modifications of sagittal shape and muscular functions in different vertebral diseases in order to investigate their correlations and to specify the role of hip extension in standing posture. MATERIALS AND METHODS: We included 57 patients presenting various diseases, among which lumbar kyphosis, spondylosis and spondylolisthesis, backache and lumbar stenosis. We measured joint mobility (hip extension, lumbar flexion), muscular retractions (ilio-psoas, hamstrings, rectus femoris), and muscular strength (spine flexors and extensors, hamstrings, quadriceps femoris). On standing lateral x-rays, measurements were made of various spinal and pelvic parameters, among which the "pelvi-femoral angle", proposed by the authors for hip extension evaluation. RESULTS: There was a significant correlation between pelvi-femoral angle and pelvic backward tilting (r = 0.8037 p < 0.01). This angle can therefore be considered as fundamental for evaluation of sagittal posture. Characteristic abnormalities were found for each pathogenic group, notably for lumbar kyphosis and spondylolisthesis. DISCUSSION: Upright posture is secondary to hip extension and lumbar lordosis, and an optimal and economic standing posture is obtained when balance between these two phenomena is correct. In lumbar kyphosis pelvic modifications such as hip extension, and pelvic backward tilt-up arise compensating the anterior displacement of the center of gravity, while in spondylolisthesis, anterior displacement is secondary to sacral obliquity. CONCLUSION: It is very important to evaluate the pelvis position in sagittal spinal diseases, in order to understand postural deterioration mechanisms. Lumbar kyphosis and spondylolisthesis are two examples of failure of upright posture.

Study of the course of the incidence angle during growth.

Standing posture is made possible by hip extension and lumbar lordosis. Lumbar lordosis is correlated with pelvic parameters, such as the declivity angle of the upper surface of the sacrum and the incidence angle, which determine the sagittal morphotype. Incidence angle, which is different for each individual, is known to be very important for up-right posture, but its course during life has not yet been established. Incidence angle was measured on radiographs of 30 fetuses, 30 children and 30 adults, and results were analysed using the correlation coefficient r and Student's t test. A statistically significant correlation between age and incidence angle was observed. Incidence angle considerably increases during the first months, continues to increase during early years, and stabilizes around the age of 10 years. Incidence is a mark of bipedism, and its role in sagittal balance is essential.

Asymptomatic cervical haemangioma treated by percutaneous vertebroplasty.

We report a 17-year-old asymptomatic patient with a partially collapsed seventh cervical vertebra due to a haemangioma revealed by conventional radiographs performed for army enrollment. Given radiological evidence of aggressiveness, percutaneous vertebroplasty by injection of methyl methacrylate cement was performed to prevent complications. CT a year later showed no progression of the lesion. The patient remains asymptomatic.

[Spontaneous vertebral pseudarthrosis in ankylosing spondylitis. Apropos of 3 cases]. / Pseudarthrose rachidienne spontanée sur spondylarthrite ankylosante. A propos de 3 observations.

PURPOSE OF THE STUDY: The authors describe the surgical treatment of three cases of vertebral pseudarthrosis in two patients suffering from rheumatoid spondylitis for an average of 20 years. MATERIAL: Two pseudarthrosis involved the thoracic level (T9-T10 and T10-T11), after an insignificant trauma. In the other case, the lesion was a secondary localization (L5-S1) arising spontaneously two years after the treatment of a T10-T11 lesion. Initial conservative treatment was unsuccessful in all three cases. Anterior surgery was performed in all three cases. In two out of the three, posterior surgery was associated with the anterior approach. RESULTS: After surgery, the three lesions healed. DISCUSSION: Extensive discovertebral lesions during the course of rheumatoid spondylitis are well known. The authors discuss the pathophysiological mechanisms, the diagnostic difficulties of such lesions in patients referred for chronic spinal pain, and the choice of treatment. CONCLUSION: Surgical treatment was considered necessary in view of the mechanical solicitations of the mobile segment. A double approach, both anterior and posterior, gave good results and is advocated by the authors.

Thoracic spinal trauma and associated injuries: should early spinal decompression be considered?

The relative benefits of conservative or surgical treatment in thoracic spinal trauma are still controversial. Owing to its anatomic relations, thoracic spinal trauma is specific regarding neurologic prognosis, the high incidence of associated injuries, and surgical management. Over a 30-month period, 49 patients sustained thoracic spinal trauma with neurologic impairment. The authors review population characteristics, associated injuries, and surgical management, and underline the high incidence of associated injuries, in particular, blunt chest trauma. In their opinion, early spinal decompression has no indication in complete paraplegia. Concerning partial paraplegia, early surgery may enhance neurologic recovery. Nevertheless, they suggest three main criteria in deciding whether or not to perform surgery early: the existence of residual spinal compression, the degree of neurologic impairment, and the presence of potential hemorrhagic lesions or blunt chest trauma, especially pulmonary contusion.

Anterior evacuation of a spontaneous cervical epidural hematoma.

The case of a spontaneous cervical epidural hematoma treated by anterior corporectomy and arthrodesis is reported. An anterior approach is preferable when an epidural hematoma is anterior to the dural sac and when MRI shows an aspect of old clotted blood that can not be easily evacuated by a posterior laminectomy.

Anterior discectomy without interbody fusion for cervical disc herniation.

Between 1985 and 1990, 68 patients with cervical radiculopathy due to soft disc herniation were treated by anterior cervical discectomy without interbody fusion. Eleven patients were unavailable for follow-up examination. The mean follow-up was 23 months (range 12-54 months). Both clinical and radiographic follow-ups were done, and 92% of the patients was found to have excellent or good clinical results. Radiographic follow-up revealed that 34% had fused spontaneously and 66% developed fibrous healing of the disc space with an average range of mobility of 2.07 deg. All patients were shown to be stable on flexion-extension films. Complications included two transient CSF leaks. No neurologic deficits arose. One patient was reoperated and fused for intractable residual neck pain. We conclude that anterior cervical discectomy without interbody fusion is a simple, safe and effective procedure for patients with soft disc herniation.