Reference values of four measures of craniocervical stability using upright dynamic magnetic resonance imaging

PURPOSE

To establish reference ranges for four most commonly used diagnostic measures of craniocervical instability (CCI) in three cervical sagittal positions. This necessitated development of a reliable measurement protocol using upright, dynamic MRI (udMRI), to determine differences in the extent of motion between positions, and whether age and sex correlate with these measures.

MATERIALS AND METHODS

Deidentified udMRIs of 50 adults, referred for reasons other than CCI, were captured at three positions (maximal flexion, maximal extension and neutral). Images were analyzed, providing measures of basion-axial interval, basion-axial angle, basion-dens interval (BDI) and the Grabb-Oakes line (GOL) for all three positions (12 measures per participant). All measures were independently recorded by a radiologist and neurosurgeon to determine their reliability. Descriptive statistics, correlations, paired and independent t-tests were used. Mean (± 2 SD) identified the reference range for all four measures at each craniocervical position.

RESULTS

The revised measurement protocol produced inter-rater reliability indices of 0.69-0.97 (moderate-excellent). Fifty adults' (50% male; mean age 41.2 years (± 9.7)) reference ranges for all twelve measures were reported. Except for the BDI and GOL when moving between neutral and full flexion, significant extents of movement were identified between the three craniocervical positions for all four measures (p ≤ 0.005). Only a minor effect of age was found.

CONCLUSIONS

This is the first study to provide a rigorous standardized protocol for four diagnostic measures of CCI. Reference ranges are established at mid and ends of sagittal cervical range corresponding to where exacerbations of signs and symptoms are commonly reported.

Septic Arthritis of the Atlanto-Occipital Joint Caused By S. Intermedius in a 5-Year-Old Girl: A Case Report

Septic arthritis of the atlanto-occipital joint caused by Streptococcus intermedius is extremely rare. We present the first case report of this entity in a fully immunocompetent 5-year-old girl. The magnetic resonance imaging and blood tests were consistent with septic arthritis, so she started empirical antibiotic therapy. Septic arthritis should be excluded in children with torticollis, fever and neck pain.

[Pathomorphological change of the atlanto-occipital segment of vertebral artery related with cervical vertigo]

OBJECTIVE

To explore the pathomorphological change of the atlanto-occipital segment of vertebral artery (V3 part) related with cervical vertigo.

METHODS

From June 1999 to November 2011, the pathomorphological change of the atlanto-occipital segment of vertebral artery were observed in 1680 patients with cervical vertigo using 3D-CTA technology. The clinical data of these patients were analyzed. There were 783 males and 897 females, aged from 22 to 70 years old with an average of 52.8 years old. Doppler examination showed vertebral basilar artery flow velocity to speed up or slow down.

RESULTS

The blood vessel of 3360 branches were detected in 1680 patients and 2778 branches were detected out vascular anomaly. And 829 branches were in V1 segment, 421 were in V2, 328 were in V3, 1190 were in V4. The pathomorphological changes in the atlanto-occipital segment (V3) of vertebral artery included angiospasm, congenital absence, abnormal exit, localized stenosis.

CONCLUSION

There are 4 kinds of pathomorphological changes in the atlanto-occipital segment of vertebral artery related with cervical vertigo. The 3D-CTA result can be used to judge prognosis and adopt reasonable treatment for the patients.

Atlanto-axial approach for cervical myelography in a Thoroughbred horse with complete fusion of the atlanto-occipital bones

A 2-year-old Thoroughbred gelding with clinical signs localized to the first 6 spinal cord segments (C1 to C6) had complete fusion of the atlanto-occipital bones which precluded performing a routine myelogram. An ultrasound-assisted myelogram at the intervertebral space between the atlas and axis was successfully done and identified a marked extradural compressive myelopathy at the level of the atlas and axis, and axis and third cervical vertebrae.

Imaging of the craniovertebral junction anomalies in children

The craniovertebral junction (CVJ) is interposed between the unsegmented skull and the segmented spine; it is functionally unique as it allows the complex motion of the head. Because of its unique anatomy, numerous craniometric indices have been devised. Because of its complex embryology, different from that of the adjacent skull and spine, it is commonly the seat of malformations. Because of the mobility of the head, and its relative weight, the craniovertebral junction is vulnerable to trauma. Like the rest of the axial skeleton, it may be affected by many varieties of dysplasia. In addition, the bony craniovertebral junction contains the neural craniovertebral junction and its surrounding CSF: any bony instability or loss of the normal anatomic relationships may therefore compromise the neural axis. In addition, the obstruction of the meningeal spaces at this level can compromise the normal dynamics of the CSF and result in hydrocephalus and/or syringohydromyelia. To image the CVJ, plain X-rays are essentially useless. MR is optimal in depicting the soft tissues (including the neural axis) and the joints, as well as the bone itself. CT still may be important to better demonstrate the bony abnormalities.

Une localisation exceptionnelle de la tuberculose vertébrale Mal de Pott sous-occipital

Le mal de Pott est la forme la plus commune de la tuberculose osseuse touchant essentiellement le rachis dorso-lombaire. La localisation sous-occipitale reste exceptionnelle. Le diagnostic de cette entité est le plus souvent tardif ce qui expose à des complications graves. Les radiographies standard ne sont parlantes qu’à un stade tardif de la maladie, d'où l'intérêt de l'imagerie moderne notamment la tomodensitométrie (TDM) et l'imagerie par résonance magnétique (IRM) qui permettent un diagnostic précoce. Nous rapportons un nouveau cas de tuberculose sous-occipitale. Le diagnostic était posé sur l'imagerie en coupe et confirmé histologiquement à la biopsie transorale. Sont rappelés les aspects en imagerie de cette localisation particulière du mal de Pott.

[Changes of swallowing function and their significance in Chiari I malformation patients with dysphagia after decompression surgery]

OBJECTIVE

To survey changes of swallowing function and their significance in Chiari I malformation patients with dysphagia after Atlanto-occipital Decompression with Duraplasty by comparing water swallowing test results and other clinical features before and after surgery.

METHODS

From January 2007 to July 2010, 126 Chiari I malformation patients were treated in Neurosurgery Department of Peking University Third Hospital. Clinical data were prospectively analyzed. There were 34 cases (26.9%, 34/126) with varying severity of dysphagia. All of those patients underwent Atlanto-occipital Decompression with Duraplasty. Water swallowing tests were performed 1 day before operation and after 7-10 days to assess dysphagia severity. The improvements of other major symptoms and signs after surgery were also compared.

RESULTS

Postoperative dysphagia was improved in 23 cases (67.6%, 23/34), and drinking water test score of preoperation was (2.74±1.11). The score was significantly reduced to (1.71±0.91) after the operation (P<0.05). Other major symptoms and signs were analyzed by Fisher's exact test which showed that only neck and shoulder pain (P=0.01) improved significantly, compared with preoperation.

CONCLUSION

Indeed part of the Chiari I malformation patients suffer from varying severity of dysphagia. The detailed clinical history collection and physical examination may improve the initial detection rate of dysphagia. Water swallow test is useful to quantify the degree of dysphagia. Atlanto-occipital Decompression with Duraplasty can improve treatment of Chiari I malformation patients with dysphagia. Improvement in treating dysphagia shortly after operation may be an effective index to evaluate the effect of surgery.

Craniovertebral junction Pott's disease

Pott's disease of the craniovertebral junction is extremely rare. The authors studied the immediate and long-term outcome after transoral decompression, occipitocervical stabilization with fusion and antitubercular therapy (ATT) in patients who had neurological deficits due to craniovertebral junction (CVJ) tuberculosis. This is a retrospective study of the management and outcome in 10 consecutive patients in whom features of spinal cord (with or without) compression were observed, and CVJ tuberculosis was diagnosed in two different neurological departments between 1990 and 2002. They ranged in age from 15 to 72 years. The onset of symptoms was either acute or subacute. Patients presented with neck and occipital pain (90%), progressive tetraparesia (40%), sensory symptoms (40%), neck stiffness (30%) and urinary dysfunction (20%). The disease caused spinal cord compression in six patients, atlantoaxial dislocation in five patients, basilar impression in one and upper vertebral column destruction without dislocation in three. Two patients presented with multiple spinal tuberculosis. Antitubercular therapy was used in all cases for 15 months. Surgical treatment performed in all patients. Four patients underwent transoral drainage of retropharyngeal abscess with granulation tissue and one odontoidectomy. Six patients then underwent occipitocervical (occiput -C3 or -C4) fusion with insertion of titanium plate and screw. Postoperatively, ATT was prescribed for 15 months. At long-term follow-up (median 50.2 months), functional status considerably improved. Two patients died 2 months later due to myocardial infarction. Patients with CVJ with features of cervical myelopathy are ideally treated with transoral decompressive procedures followed by occipitocervical fusion, because this therapy provides immediate neurological improvement, stability and allows early mobilization. The long-term prognosis in patients with this disease is excellent, provided it is treated with appropriate surgical intervention and with adequate duration of ATT. This approach provides excellent access to this region, with a low operative morbidity and no mortality.

Ventrally placed craniovertebral junction arachnoid cysts in children: a report of 2 cases and literature review

BACKGROUND

Arachnoid cysts at the craniovertebral junction are uncommon, and all the reported cases had location posterior to the brain stem. We describe 2 cases of ventral arachnoid cysts among children.

CASE DESCRIPTION

Two children, in their first decades of life, presented with spastic quadriparesis without complaints of raised intracranial pressure. Magnetic resonance imaging showed large, ventrally located cystic lesions compressing the brain stem and extending from posterior fossa to the lower level of C4 vertebra. Both patients underwent surgery via midline posterior fossa approach and fenestration of cysts along with partial excision. Both patients made complete recovery and are asymptomatic in the long-term outcome.

CONCLUSION

Ventral arachnoid cysts at the craniovertebral junction present in the pediatric age group because of compression of corticospinal tracts. These patients have good long-term outcome after fenestration and partial cyst excision.

Contemporary posterior occipital fixation

Occipitocervical fixation is technically demanding but necessary in many clinical scenarios where junctional occiptocervical instability is present. The surgeon must have a thorough knowledge of the associated anatomy, biomechanics of spinal instrumentation, and familiarity with an ever-growing number of stabilization techniques and implants. The nature of the injury, the patient's anatomy, and the quality of the host bone will ultimately determine which form of fixation is optimal. Although the contemporary modular systems, at first glance, appear to add significant surgical complexity, in truth the designs actually simplify the process by allowing the surgeon to place occipital and spinal anchors in optimal anatomic locations.

Dysplasia of C-1 and craniocervical instability in patients with Shprintzen-Goldberg syndrome. Case report and review of the literature

Shprintzen-Goldberg syndrome is a rare connective tissue disorder characterized by marfanoid habitus and additional dysmorphic stigmata. Craniocervical anomalies occur in fewer than 30% of cases. Serious vertebral instability can also occur, albeit rarely. The authors report on the first patient treated with surgical fusion at the craniocervical junction because of a C-1 dysplasia and severe instability. The skeletal and cardiovascular anomalies that can pose additional problems for surgical treatment and perioperative care are discussed in detail.

Long-term incidence of subaxial cervical spine instability following cervical arthrodesis surgery in patients with rheumatoid arthritis

OBJECTIVE

Cervical spine deformities are well-known complications of RA. A 5- to 20-year follow-up of 51 consecutive rheumatoid patients who underwent posterior cervical arthrodesis is presented to evaluate the recurrence of instability and need for further surgery.

METHODS

We conducted a retrospective review of the clinical features of 11 men and 40 women with an established diagnosis of RA and associated cervical deformities who underwent cervical spine surgery at the Mayo Clinic (Rochester, MN) between 1979 and 1990. Their mean age was 61 +/- 10 years (SD), and their duration of RA averaged 21 +/- 8.9 years (SD). There were 22 patients who presented with myelopathy, 7 with radiculopathy, and 22 with instability/neck pain. There were 33 patients with AAS, 2 with SMO process into the foramen magnum, 8 with SAS, and 8 with combinations of these. Preoperative reduction was followed by decompression and fusion using wiring techniques and autologous bone graft. Postoperative halo orthosis was provided for at least 3 months. The mean follow-up was 8.3 +/- 6 years (SD).

RESULTS

There were 31 patients (61%) who underwent atlantoaxial arthrodesis, 17 patients (33%) who underwent subaxial, and 3 patients (6%) who underwent occipitocervical arthrodesis. During follow-up, 39% (13/33) of patients with AAS developed nonsymptomatic (6) or symptomatic/unstable (7) SASs subsequent to C1-C2 fusion. The latter 7 patients (21%) subsequently required extension of their arthrodesis. Adjacent segment disease was most common at the C3-C4 interspace after atlantoaxial fusion in 62% (8/13). Among the 8 patients who underwent isolated cervical fusion for SAS, 1 patient (1/8, 12%) developed adjacent instability after a fall and required extension of the previous fusion. No secondary procedure was required for the 6 patients initially stabilized by C1-(C6-T1) fusions for combinations of AAS + SAS. None of the patients initially treated by C1-C2 arthrodesis for AAS progressed to SMO.

CONCLUSIONS

The incidence of subaxial instability in patients with rheumatoid disease who underwent cervical arthrodesis may be higher than previously reported, indicating the need for continued follow-up in these patients. Adjacent segment disease may be most common at the C3-C4 level following atlantoaxial fusion. Early stabilization of the C1-C2 complex in the patients with AAS may potentially prevent progression of SMO.

Neurenteric cysts in children: 16 consecutive cases and review of the literature

OBJECT

The authors of this retrospective review and analysis of the literature cover an institutional series of neurenteric cysts of the central nervous system in children treated in the magnetic resonance imaging era during a 14-year period.

METHODS

Sixteen patients 20 days to 14 years of age are described. The most frequent signs and symptoms at presentation were acute spinal cord compression (11 patients), paresis of a cranial nerve (two patients), meningitis or infection (two patients), and intracranial hypertension (one patient). The locations of the cysts were as follows: in the spinal canal in 12 patients (75%), the clivus in two (12.5%), the cavernous sinus in one (6%), and the craniocervical junction in one (6%). The most common location was the ventral aspect of the spinal canal (seven patients). Associated spinal deformities were found in five patients. All patients underwent surgery, with a posterior approach used in all of the spinal cases. Total resection was achieved in 12 of the 16 cases and partial resection in four. Of the four patients who underwent subtotal resection, the cyst recurred in three, requiring further surgery.

CONCLUSIONS

Neurenteric cysts are uncommon congenital anomalies that can present acutely in the pediatric population. Total removal is usually possible and is associated with a good prognosis.

Traumatic atlanto-occipital dislocation in children

BACKGROUND

Traumatic atlanto-occipital dislocation in children and adolescents is a rare and often fatal injury. Although historically most reported cases have been fatal, the advent of modern prehospital care has led to an increase in survival following this injury. As a consequence, some patients may achieve or maintain satisfactory neurologic function following early intervention, stabilization, and definitive management. We analyzed the data on children and adolescents in whom traumatic atlanto-occipital dislocation had been treated with modern resuscitation techniques at our institution.

METHODS

Atlanto-occipital dislocation is defined as disruption of the ligaments and other supporting soft tissues as indicated by displacement in either a transverse or vertical direction. With use of the Trauma Registry database at our institution, we identified sixteen such injuries that had occurred between 1986 and 2003. The hospital charts, clinic notes, and radiographs were reviewed. A careful neurological evaluation was performed for all of the survivors at the time of the latest follow-up.

RESULTS

The mean age of the sixteen patients at the time of the injury was 7.6 years. The mechanisms of injury were diverse. The mean Glasgow Coma Scale score was 7.4 points. Eleven of the sixteen patients underwent intubation in the field, two were intubated in the emergency department, and three were not intubated. Eight of the sixteen patients were declared dead on arrival in the emergency department. The eight surviving patients initially were immobilized with either a halo vest or another orthosis. All patients except one received intravenous steroids in the emergency department. Three of the patients who survived the initial injury subsequently died while undergoing neurosurgical procedures for the treatment of extensive intracranial injuries. Four of the remaining five survivors underwent occiput-C2 fusion, and one was managed with a Minerva cast. At the time of the final follow-up, at a mean of 4.2 years after the injury, one patient was neurologically normal, three had mild spastic hemiparesis and were very functional, and one had spastic quadriplegia and was ventilator-dependent.

CONCLUSIONS

Prompt recognition and treatment of traumatic atlanto-occipital dislocation in children and adolescents can result in improved survival. Early diagnosis, prompt intubation, early and adequate immobilization of the head and neck, and the use of intravenous steroids appear to facilitate survival. We recommend arthrodesis from the occiput to C2 (or the nearest adjacent intact and stable vertebra caudad to C2) for all children who survive a traumatic atlanto-occipital dislocation, particularly those with an incomplete spinal cord injury.

A Case Report of Manipulation Under Anesthesia of Posttraumatic Type II Occipital-Atlantoaxial Rotatory Subluxation in a 4-Year-Old Girl

OBJECTIVE

To discuss a case of occipital-atlantoaxial rotatory subluxation successfully treated with manipulation under general anesthesia.

CLINICAL FEATURES

A 4-year-old girl presented to the Taichung Veterans General Hospital with acute torticollis and neck stiffness for 1 week after she had fallen. Although some nonsteroidal anti-inflammatory drugs had been prescribed for her, her neck still tilted to the right side and her chin inclined to the left side. There were no neurological signs, no significant pain if she did not move her neck and head, and no muscular hypertonocity. There was painful guarding in the right sternocleidomatoid muscle when manipulation was attempted. Three-dimensional computer tomography revealed uneven joint space between the C1 anterior arch and odontoid process and confirmed a type II atlantoaxial rotatory subluxation.

INTERVENTION AND OUTCOME

Manipulation under anesthesia was performed by a medical doctor trained in manual therapy. The low-velocity, right rotational manipulation applied to the occiput included axial traction. The neck symptoms were relieved immediately after treatment.

CONCLUSION

Under general anesthesia, manipulation may be a good method for treating noncomplicated type II atlantoaxial rotatory subluxation. Additional investigations may be necessary to evaluate the treatment effect.

[Surgical aspects of the cervical spine in rheumatoid arthritis]

Approximately 20% percent of the patients with rheumatoid arthritis show pathology in the cervical spine. The translational instability between axis and atlas might be painful and leads in the long term to myelopathic changes due to chronic traumatization of the myelon. Ongoing osseous resorption of the lateral masses of the atlas cause upward migration of the dens into the foramen magnum. In the subaxial cervical spine, the inflammatory process causes instability and deformity. Neck pain is the most common indication for surgery, but neurological symptoms with myelopathy or radicular deficits might be the primary cause for surgery. Neurophysiological investigation is suitable to obtain objective results. Stabilization of the atlantoaxial segment is the most common procedure for treatment of atlantoaxial instability. It is performed by screw fixation technique from a posterior approach. In case of severe occipitocervical dislocation, the fixation has to be extended to the occiput. Persistent dislocation or compression by the dislocated dens has to be treated by transoral decompression. In the subaxial spine, instabilities may be treated by posterior plate fixation with lateral mass screws or pedicle screws. Concomitant nar-rowing of the spinal canal should be approached by anterior decompression with corpectomy and/or posterior laminectomy. The timing of surgery in rheumatoid patients is crucial to obtain satisfactory clinical results.

Ultrasound-guided atlanto-occipital puncture for myelography in the horse

Complications of cervical myelography arising from the puncture of the subarachnoid space to collect the cerebrospinal fluid and to inject the contrast medium have been described in humans and animals. In this study, 2 ultrasound-guided procedures were developed for puncture of the atlanto-occipital subarachnoid space, collection of cerebrospinal fluid, and injection of contrast medium. Myelography was performed on 6 ataxic horses using these procedures. The first attempt to puncture the subarachnoid space was successful in 5 horses and in one horse, a second attempt was necessary. Collection of cerebrospinal fluid and injection of contrast medium were achieved without difficulty. Ultrasound-guided myelography allowed reduction of potential complications associated with blind percutaneous puncture of the subarachnoid space. Methods described in this study should be tried-at least initially in an experimental setting--to collect cerebrospinal fluid from the atlanto-occipital site in standing horses where it may represent an alternative method when lumbosacral cerebrospinal fluid collection has been unsuccessful or contaminated with blood.

[The efficiency of spinal manipulation in otorhinolaryngology. A retrospective long-term study]

BACKGROUND

The vertebral genesis of many functional disorders in otorhinolaryngology, such as dizziness, hearing-impairment, ear-pressure, ear-pain, foreign body sensation in the throat and dysphonia, is suggested by the success of spinal manipulative therapy, particularly of the atlanto-occipital joint. Up to now, there are no retrospective investigations which show the duration of the therapeutic effect.

METHODS

We examined 220 patients with cervical otorhinolaryngological disorders (100 patients with dizziness, 49 with hearing impairment, 47 with tinnitus and 24 with dysphonia) after cervical manipulation lasting more than 6 months.

RESULTS AND CONCLUSIONS

The extraordinary satisfaction with the manipulative therapy in 82% of patients with dizziness (46% total relief, 36% high improvement) reflects the high efficiency of this manual therapy. In contrast to these results, only 10% of patients with tinnitus showed an improvement (P<0.001). This retrospective investigation demonstrates that a successful outcome after manual therapy is not based on a "placebo effect".

Complete surgical excision of intramedullary schwannoma at the craniovertebral junction in neurofibromatosis type-2

Intramedullary spinal schwannomas are extremely rare. We describe a case of a 13-year-old female who was found to have an intramedullary schwannoma at craniovertebral junction along with incidental bilateral acoustic neuromas, which was excised completely. To our knowledge, this is the first report of a case of intramedullary schwannoma in association with NF-2 located at the craniovertebral junction. The literature has been reviewed with emphasis on radiological imaging, histopathological diagnosis and technique to achieve complete microsurgical excision.

Atlanto-occipital dislocation: a case report and review of the literature

Although traumatic atlanto-occipital dislocation is perceived to be an uncommon injury frequently resulting in death, improvements in emergency management of the patient in the field, rapid transport, and better recognition have resulted in more survivors of atlanto-occipital dislocation in the past 2 decades. Infrequent observation of patients with atlanto-occipital dislocation and missed diagnosis may impair outcomes of patients with this unusual injury. The case of atlanto-occipital dislocation that is presented here is particularly interesting because the patient was missed diagnosis for eight months after the accident. He came to Prasat Neurological Institute by wheel chair with tetraparesis and could not help himself. After investigation by cervical spine radiograph and MRI of the cervical spine confirming the diagnosis, he was operated on the following day. The plates were fixed in the occipital bone and lateral mass of the cervical spine on both sides, craniectomy of the occipital bone at the foramen magnum and laminectomy C1 for decompression, then auto bone graft was fused at the occiput and C2. After the operation the patient was sent for 3 months physical therapy, he improved well and gained power of the extremities and could walk with a walker.

[Dural fistula in the craniocervical junction. A case report and review of the literature]

INTRODUCTION

Spinal dural fistulas consist in an artery that penetrates into the dura mater and drains into a perispinal vein. They are most commonly located in the dorsal or lumbar region; a craniocervical position is infrequent. The clinical features presented by these patients involve an progressive ascending myelopathy caused by severe venous hypertension, although they can also start with symptoms of a subarachnoid haemorrhage.

CASE REPORT

A 62 year old male with symptoms of progressive myelopathy due to a dural fistula dependent on meningeal branches of the right PICA, which was treated surgically by fistula clipping performed using an extreme lateral suboccipital approach. In the literature that was reviewed there were 35 cases of dural fistulas located at the craniocervical junction.

CONCLUSIONS

The existence of clinical features compatible with cervical myelopathy and an anodyne cervical resonance justify the need to perform medullar arteriography owing to a suspected vascular malformation. An early diagnosis of a dural fistula and its proper treatment lead to a diminished morbidity and mortality rate in these patients.

Stability analysis of craniovertebral junction fixation techniques

BACKGROUND

Craniovertebral arthrodesis in the upper cervical spine is challenging because of the high degree of mobility afforded by this region. A novel method for achieving atlantoaxial fixation with use of polyaxial screws inserted bilaterally into the lateral masses of C1 and transpedicularly into C2 with longitudinal rod connection has recently been introduced. The question remains as to whether this technique provides adequate stability when extended cephalad to include the occiput. The purpose of this study was to determine the primary stability afforded by this novel construct and compare its stability with the current standard of bilateral longitudinal plates combined with C1-C2 transarticular screws.

METHODS

We used ten fresh-frozen human cadaveric cervical spines (C0-C4). Pure moment loads were applied to the occiput, and C4 was constrained during the testing protocol. We evaluated four conditions: (1) intact, (2) destabilized by means of complete odontoidectomy, (3) stabilization with longitudinal plates with C1-C2 transarticular screw fixation, and (4) stabilization with a posterior rod system with C1 lateral mass screws and C2 pedicle screws. Rigid-body three-dimensional rotations were detected by stereophotogrammetry by means of a three-camera system with use of marker triads. The range of motion data (C0-C2) for each fixation scenario was calculated, and a statistical analysis was performed.

RESULTS

Destabilization of the specimen significantly increased C0-C2 motion in both flexion-extension and lateral bending (p < 0.05). Both fixation constructs significantly reduced motion in the destabilized spine by over 90% for all motions tested (p < 0.05). No significant differences were detected between the two constructs in any of the three rotational planes.

CONCLUSIONS

Both hardware systems provide equivalent construct stability in the immediate postoperative period when it is critical for the eventual success of a craniovertebral arthrodesis. On the basis of this work, we believe that the decision to use either construct should be determined by clinical rather than biomechanical concerns.

Antinociceptive potency of intrathecal morphine in the rat tail flick test: a comparative study using acute lumbar catheter in rats with or without a chronic atlanto-occipital catheter

Chronic spinal catheterization via an atlanto-occipital puncture (CAO) has been widely used to study the effects of drugs on spinal nociceptive mechanisms, but this method is associated with spinal cord damage that may change the efficacy of spinally injected analgesics. Using a slight modification of the method of Storkson et al. (J. Neurosci. Methods 65 (1996) 167), the rat spinal cord was acutely catheterized via a lumbar puncture (AL) and the potency of morphine-induced antinociception in the tail flick test was comparatively studied in animals with or without a CAO catheter. The opiate potency via an AL catheter (AD50; 95% confidence limits) was significantly more intense in rats without (0.29 microg; 0.19-0.47) than in rats with a CAO catheter (1.1 microg; 0.87-1.47) and stronger than via a CAO catheter (8.2 microg; 4.6-14.4). The potency of morphine via a CAO catheter was significantly improved in indomethacin-pretreated rats (1 mg/kg, i.p., twice a day for 5 days), thus indicating that inflammatory changes produced by a CAO catheter are at least in part the reason for the lower efficacy of the opiate. The use of an AL catheter minimizes such spinal changes and permits acute experimental protocols in which more than one spinal injection is necessary.

Nuchal fibrocartilaginous pseudomotor. Case report and review of the literature

The case of a 30-year-old woman who, many years after a trauma to the neck, developed a hard tissue mass in the posterior midline at C5-C6 level is reported. The patient underwent surgical excision of the mass. Nucal fibrocartilaginous pseudotumor (NFP) was diagnosed. This is a very rare non-neoplastic lesion, probably arising throug a post-traumatic metaplasia of the nuchal ligament, and only 14 cases have been reported to date in the literature. The clinicopathologic and neuroradiologic features of NFP are described.

[Inside-outside occipito-cervical fixation: technical report]

The clinical knowledgement of biomechanics of atlantoaxial complex have been proved that progressive instability has a mandatory occurrence after anterior decompression of the craniocervical junction. We report the occípitocervical fixation so called inside-outside technique, originally described by Pait et al. appliedin in two patients whom underwent odontoidectomy. The occipitalcervical fixation technique consist in the use of a titanium rod bended according with occipital cervical angle placed and fixed laterally over the cervical spine. The rod is fixed to the occipital bone by mean of placement a screw which flat portion is positioned onto the epidural space. In the cervical spine the rod is attached to transarticular screws placed at the superolateral quadrant of the articular mass. In the axis the screw is introduced through the pars interarticularis finishing at the axis body or the lateral mass of the atlas. This technique proved to be safe and easily applied in the patients whom underwent this surgical procedure.

Management of osteomyelitis of the anterior skull base and craniovertebral junction

OBJECTIVES

The study goals were to determine the patient demographics, identify predisposing factors, and determine efficacy of treatment for nonotologic osteomyelitis of the skull base and craniovertebral junction.

STUDY DESIGN

All patients with a biopsy-proven diagnosis of osteomyelitis of the skull base treated by the author from 1997 through 2001 were retrospectively evaluated.

RESULTS

Six patients were identified on review. The average age at presentation was 56.7 years (age range, 38 to 70 years), and all except one patient had an underlying immunocompromising condition (diabetes mellitus, human immunodeficiency virus infection, steroid use). Most presented with neurologic deficits associated with a destructive lesion of the osseous skull base. Aggressive debridement of involved bone enabled through the use of broad field standard skull base approaches was associated with clinical resolution of symptoms in each case. Systemic antibacterial/antifungal therapy and medical optimization remain important adjuncts in the treatment of this group of patients.

CONCLUSION

The diagnosis of this entity may be difficult to discern from neoplastic involvement of the skull base. Standard skull base approaches are useful for both the diagnosis and the treatment of nonotologic osteomyelitis.

Upper cervical spine injuries

The unique anatomy of the upper cervical spine and the typical mechanisms of injury yield a predictable variety of injury patterns. Traumatic ligamentous injuries of the atlanto-occipital joint and transverse atlantal ligament are relatively uncommon, have a poor prognosis for healing, and often respond best to surgical stabilization. Bony injuries, including occipital condyle fractures, atlas fractures, most odontoid fractures, and traumatic spondylolisthesis of the axis, generally respond well to nonsurgical management. Controversy in management remains, however, especially with type II odontoid fractures.

Neurenteric cyst of the craniocervical junction. Report of three cases

Neurenteric cysts of the craniocervical junction (CCJ) are very rare lesions. Their origin is the subject of long-standing controversy, but a failure during the embryogenic phase may be responsible for their formation. Accurate histopathological diagnosis may be difficult due to the similarity they share with other cystic lesions such as colloidal cysts, Rathke cysts, and cystic teratomas. Surgical removal is the treatment of choice for intracranial neurenteric cysts, but in some cases, infiltration of the surrounding structures may hinder complete resection. Three cases of neurenteric cysts located at the CCJ are reported.

Harvesting the intact cadaveric cervical spine (C0-Th1)

STUDY DESIGN

Technical report on harvesting method for human cadaveric cervical spine.

OBJECTIVES

Description of a new method for harvesting the intact cervical spine during routine autopsies, including the atlanto-occipital and cervico-thoracic joints, without visible disfigurement above the suprasternal notch.

SUMMARY OF BACKGROUND DATA

Despite the need for cervical spine specimens, there are only few articles describing procedures for harvesting an intact cervical spine. Presently available techniques either do not preserve the atlanto-occipital joint or leave visible disfigurement.

METHODS

The body was placed in a prone position with the head flexed, and a posterior midline incision was performed. The spine was separated from surrounding tissue, then the caudal end was cut off through the Th1/Th2 disc space. A circular craniotomy provided access to the cranial base. A square window surrounding the foramen magnum was cut at the cranial base (through the sella turcica, the internal occipital protuberance, and 5 cm parasagittal on either side), and the entire cervical spine extracted through the posterior incision. The defect was reconstructed using wood and plaster materials.

RESULTS

Eighteen specimens were harvested to date using this method. The average time of harvesting the cervical spine was less than 30 minutes. Reconstruction using wood and plaster resulted in a nearly normal appearance of the neck.

CONCLUSIONS

Using this technique, the nuchal ligament providing stability to the cervical spine can be preserved. The suggested method was found simple, efficient, and reproducible for harvesting the intact cervical spine, including the atlanto-occipital and cervico-thoracic joints, from any routine autopsy.

Atlanto-occipital dislocation: an unusual lethal airbag injury

Airbag-induced injury fatality is increasing in frequency. We present the case of a 6-year-old passenger who sustained a fatal atlanto-occipital dislocation associated with airbag deployment in a low-speed motor vehicle crash. The current literature regarding airbag fatalities and methods to ameliorate airbag-induced injury are reviewed.

Minimally invasive techniques in neurosurgery: the transoral transpharyngeal approach to the brain

In 30 cases, an analysis of the transoral transpharyngeal approach to the ventral brain stem was made. All preparations were performed in situ using microscopic and endoscopic methods. Modern imaging techniques and computer-assisted approach planning were also applied and discussed. To show the subarachnoidal cisterns and receive a realistic impression of the tissue, the preparation was performed 26 times in non-fixed cases. To use currently available equipment safely, it is important to take anatomical details into account when determining the size and type of the clivus window to be used. Preparation of the preclival tissue is the most difficult step. It requires a precise approach plan to ensure safe closure. This selective approach gives the best access to the lower ventral brainstem, without any of the problems associated with other approaches to the same region. The transoral transpharyngeal approach is described here within the context of minimally invasive techniques, in particular endoscopy, modern imaging methods, and computer-assisted approach planning.

A rat model of chronic lumbar epidural catheterisation

PURPOSE

There are no rodent models of chronic epidural catheterisation which can induce clinically relevant analgesic effects of morphine (potency ratio of intrathecal:epidural = 10 to 30:1). The purpose of this study was to investigate a new rat model of chronic epidural catheterisation by comparing the analgesic effect of epidural and intrathecal morphine.

METHODS

In Sprague-Dawley rats, for epidural catheterisation, a skin incision and muscle dissection were made at T13 level in the midline. The intervertebral ligament was cut to insert an epidural catheter (polyethylene tube; outer diameter 0.14 mm) 2 cm caudally. The distal end of the catheter (0.61 mm) was passed s.c. to exit in the dorsal neck area. For intrathecal catheterisation, the atlanto-occipital membrane was incised to insert a catheter (0.61 mm) 8.5 cm caudally. The effects of morphine (1, 3, 10, 30, or 100 micrograms.10 microliters-1 intrathecally, and 30, 100, or 300 micrograms.5, 10, or 20 microliters-1 epidurally) on thermal escape latency were investigated by a hot box test. Behaviour and motor function were also tested.

RESULTS

A volume of 20 microliters induced greater analgesic effect than 5 and 10 microliters epidural administration. The ED50 of epidural morphine (94.1 micrograms) was 30 times more than that of intrathecal morphine (3.1 micrograms).

CONCLUSION

A new rat model of chronic epidural catheterisation is described, which provides a similar analgesic epidural: intrathecal potency ratio for morphine to that in humans when morphine is administered in a volume of 20 microliters.

Cerebrospinal fluid constituents collected at the atlanto-occipital site of xylazine hydrochloride sedated, healthy 8-week-old Holstein calves

Cerebrospinal fluid (CSF) collected at the atlanto-occipital site and serum were obtained from 10 male, 8-week-old, Holstein calves after sedation with xylazine hydrochloride. Glucose, creatine kinase, alkaline phosphatase, urea nitrogen, creatinine, sodium, potassium, chloride, calcium, phosphorus, total protein, and albumin were determined in serum and CSF. Optical characteristics, specific gravity, total red blood cell and nucleated cell counts and differentials were also evaluated in the CSF. Additionally, CSF protein electrophoresis and immunoglobulin concentrations were determined. Then, albumin quotients (AQ) were derived. Erythrocytes were observed in 9 of 10 CSF samples. Total nucleated cell counts ranged from 0-10 cells x 10(6)/L with a mean of 3 cells x 10(6)/L. Differential nucleated cell count in the CSF consisted primarily of lymphocytes/small mononuclear cells (57%), fewer monocytes/ large mononuclear cells (38%), and scant neutrophils (4%) and eosinophils (0.05%). The concentration of sodium (134 to 139 mEq/L) was similar to that of serum, but the concentration of potassium (2.8 to 3 mEq/L) was lower than that of serum. Creatine kinase activity (0 to 4 U/L) of CSF was markedly lower than serum activity. The CSF glucose concentration was approximately 80% of the serum value. Cerebrospinal fluid total protein concentration determined by electrophoresis ranged from 110 to 330 mg/L with a mean of 159 mg/L. Cerebrospinal fluid albumin ranged from 48 to 209 mg/L with a mean of 86 mg/L. In all CSF samples, radial immunodiffusion of unaltered CSF and concentrated CSF (four-fold concentration) revealed quantities undetectable by the present techniques in which the lowest standard values for IgG1, IgG, and IgM determinations was 70 mg/L and IgG2 was 30 mg/L. The albumin quotient ranged from 0.15 to 0.65 with a mean of 0.25. Based on the results of this study, CSF may be collected at the atlanto-occipital site safely and efficiently in calves, and reported values for CSF from adult cattle may not be suitable for evaluation of CSF collected from immature cattle.

[Integrated role of computerized tomography and magnetic resonance imaging in identifying the early changes in rheumatoid arthritis of the craniocervical junction]

Any cervical spine segment may be affected by rheumatoid arthritis, but destructive changes are most prominent at the craniocervical junction. Cervical involvement is a devastating complication of the disease, because of the risk of a range of neurological complications (paresthesia, cervical myelopathy, vertebro-basilar insufficiency), and even sudden death from medullary compression. However, the incidence of both cervical rheumatoid arthritis and its neurological complications are still debated, being respectively reported in 17-86% and 11-70% of the patients, according to the variability in neurological and radiologic classification systems adopted by the authors. To assess the incidence of cervical rheumatoid arthritis and the integrated role of different imaging techniques in its diagnosis, 38 consecutive patients (29 women and 9 men) with rheumatoid arthritis according to the American Rheumatism Association criteria were examined. The average age was 60 years (range: 27-70 years) with a mean disease duration of 6.6 years (range: 6 months-25 years). All the patients underwent conventional radiography of the cervical spine, unenhanced Computed Tomography (CT) of the craniocervical junction and unenhanced and Gadolinium-enhanced Magnetic Resonance Imaging (MRI) of the cervical spine. Cervical spine involvement was demonstrated in 25/38 (66%) patients 20 women and 5 men, with an average age of 57 years and a mean disease duration of 8.5 years. In 13 of them (mean disease duration: 12.7 years), the diagnosis was made with radiography which showed atlantoaxial and subaxial subluxations and/or erosions. Of the 12 patients with negative conventional radiography (mean disease duration: 2.5 years), 4 were identified with both CT and MRI (synovial pannus and erosions). 3 with MRI only (joint effusion/hypervascularized synovial pannus), and 5 exhibited questionable CT findings which were clarified only by MR demonstration of inflammatory tissue contiguous to suspicious irregularities of the cortical bone of the odontoid process. 52% (13/25) of cervical rheumatoid arthritis patients were identified with plain radiographs, 68% (17/25) with CT and 100% (25/25) with MRI. Our preliminary data show that a specific tool for the diagnosis is recommended even in the early disease phases since rheumatoid arthritis commonly affects the craniocervical junction. Studying the craniocervical region is clinically difficult, and diagnostic imaging assessment is essential. Conventional radiography allowed to detect more than half the patients with cervical rheumatoid arthritis, but only in advanced disease stages. On the contrary, MRI had the unique potential of direct and detailed synovial visualization, thus permitting the diagnosis of cervical involvement even in the early phases of the inflammatory process, when CT findings were still negative or questionable.

Pott's disease of the cervico-occipital junction in an AIDS patient

Pott's disease of the cervical spine is relatively rare despite the fact that tuberculous spondylitis is still the most common manifestation of bone and joint infection. We describe a case, the first to our knowledge, of sub-occipital Pott's disease associated with a retropharyngeal abscess in an acquired immune deficiency syndrome (AIDS) patient. Neurological signs were the main clinical findings. The patient was successfully treated with anti-tuberculosis drugs combined with external stabilization of the spine.

Lumbar catheterization of the spinal subarachnoid space in the rat

The method commonly used for catheterization of the lumbar subarachnoid space in the rat implies inserting the catheter through the atlanto-occipital (A-O) membrane and moving the catheter caudally along the spinal cord. The method is associated with a considerable morbidity. A method for direct catheterization of the lumbar subarachnoid space was therefore developed. Major surgery was avoided by using a catheter-through-needle technique. Of 32 rats, none died. There were no signs of neurological disturbances, and all animals gained weight as normal the first week after implantation. Data from rats catheterized by the A-O method were used for comparison. Of 40 animals, 2 died, 11 showed signs of neurological disturbances, and the mean weight was reduced during the first week after catheterization. The two groups of animals showed different behavioural responses to intrathecal injection of N-methyl-D-aspartate (NMDA, 0.1-1.6 mM, 15 microliters) which is thought to stimulate afferent pathways mediating nociception. Animals with a lumbar catheter showed licking, biting and scratching behaviour in a dose-related manner for concentrations up to 1.6 mM. The animals with A-O catheters showed a maximum level of this behaviour already at 0.4 mM, while 0.5 mM induced convulsions. A possible explanation of this difference in response to NMDA could be a long-lasting pain state in the A-O group, caused by catheter-induced changes in the spinal cord and by the extensive surgery. It is concluded that the direct lumbar catheterization has several advantages compared to the A-O method, decreasing the suffering of the animals, the neurological disturbances and the interference with nociceptive functions of the spinal cord.

Microsurgical anatomy of the atlantal part of the vertebral artery

BACKGROUND

Microanatomy of the vertebral artery has been the subject of multiple studies. However, none of them has covered every aspect of microvascular anatomy of the atlantal part of the vertebral artery.

MATERIALS AND METHODS

Microsurgical anatomy of the atlantal part of the vertebral artery was studied in 14 cadaveric specimens. The artery was dissected using the standard microsurgical technique under operative microscope magnification. The atlantal part of the vertebral artery was divided into five segments: the foraminal, sagittal, transverse, medial condylar, and dural. The length of each segment was measured, as was the diameter of the artery. The branches of this part of the artery were identified and the distance between the point of dural entry of the artery and the midline of the atlanto-occipital dura was measured. Distance between the mastoid tip and the artery and the distance between the mastoid tip and the tip of C1 transverse process were measured.

RESULTS

Results of all measurements are summarized in tables and text. We discuss various anomalies, branches, and lesions of the vertebral artery and surgical approaches with new methods of managing diseases in this area.

Brachyolmia: a report of two cases

Brachyolmia is a rare form of skeletal dysplasia characterized by generalized platyspondyly without significant epiphyseal, metaphyseal, or diaphyseal changes in the long bones. Two cases of brachyolmia are reported: one of the Hobaek type, and another of the dominant type. One patient developed linear densities in the femoral necks: The manifestation is thought to be specific to the Hobaek type. Another patient had atlantoaxial instability and failure of ossification of the dens. These complications of brachyolmia have not been previously reported.