Preoperative evaluation of the cervical spine in children with trisomy-21: results of a questionnaire study

Atlantoaxial subluxation (AAS) is a form of cervical spine instability predominantly found in persons with Trisomy-21. Several case reports describe the occurrence of acute AAS in the perioperative period. Some authors have recommended cervical spine radiographs prior to elective surgery in all children with Trisomy-21. The objective of this study was to determine practice patterns of North American members of the Society of Pediatric Anesthesia with regard to the perioperative evaluation and management of potential cervical spine instability in patients with Trisomy-21. Of 171 respondents, a minority of respondents (18%) obtain preoperative radiographs and/or subspecialty consultation (9%) in asymptomatic children with Trisomy-21. For symptomatic children the majority of respondents would obtain radiographs (64%) and/or preoperative consultation (74%). Approximately half of the respondents would attempt to maintain the head and neck in a neutral position for either asymptomatic (42%) or symptomatic (55%) patients. We conclude that the majority of respondents base their preoperative evaluation of the cervical spine on the signs and symptoms of the patient. This is supported by the literature reviewed, but is contrary to the recommendations made in some case reports.

Down's syndrome and anaesthesia

Down's syndrome is a common congenital abnormality associated with characteristic morphological features, impaired intellectual development and disorders of many organ systems with a broad spectrum of severity. Many of these, including defects in cosmetic appearance, are amenable to surgical correction. The risks of anaesthesia are increased in these children. In this article the anaesthetic implications of the syndrome are reviewed and the principles of perioperative management discussed.

A method for classification of the posterior atlanto-axial subluxation

Atlanto-axial subluxation and dislocation in rheumatoid arthritis is a multidirectional abnormality. The most common subluxations take place anteriorly, vertically or laterally. Posterior atlanto-axial subluxations are rare. The distance between a line tangential to the anterior aspect of the axis (C2) and the most posterior aspect of the anterior arch of the atlas (C1) could be used to measure the displacement in posterior atlanto-axial subluxation. Routine measurement of this distance could give us a better idea of the frequency of this type of affection in rheumatoid arthritis of the cervical spine. Serial measurements might be used to estimate the progression of the disease.

Involvement of atlanto-axial joint in rheumatoid arthritis: rare or frequent?

The authors studied the incidence of atlanto-axial joint involvement by conventional radiography and CT in 183 patients with classical or definite rheumatoid arthritis (RA). In determining lesions the significance of factors such as age, sex, duration and severity of the disease was evaluated. Atlanto-axial subluxations turned out to be quite frequent (30%) in the series of patients examined and were directly correlated with age, duration and stage of the disease, and extraarticular manifestations. Clinical symptoms were evident in only 70.9% of cases, confirming the correlation reported by other authors between clinical manifestations and radiologically observed lesions. Traditional radiography performed in the dynamic position revealed a prevalence of anterior subluxation, whereas CT gave a precise indication of the entity and type of atlanto-axial lesion. In conclusion, the authors confirm the importance of such investigations in all patients with RA, even those without evident clinical manifestations. They also emphasize the necessity of periodic monitoring in view of the possible risk of mortality in these patients.

[Backward hypertranslation of the head: participation in the whiplash injury mechanism of the cervical spine?]

Based upon a review of the literature, a theory is developed that in whiplash injury the primary mechanism of the trauma is not hyperantiflexion but hypertranslation of the head backwards. Thus a hyperanteflexion (not hyperretroflexion) of the upper cervical spine, probably especially of the atlanto-axial segment, is induced, causing an overstretching of the ligaments concerned (also the alar ligaments) and the joint capsule. The disorder of the propriosensitive information concerning the position of the head relative to the body with chronic disturbances of posture and equilibrium is explained by the thus generated chronic ligamentous instability of the upper cervical spine. In humans our theory is not yet sufficiently supported by experimental results.

[Diagnosis, analysis and evaluation of functional disorders of the upper cervical spine within the scope of whiplash injuries with nuclear magnetic resonance tomography]

We tested the diagnosis of malfunctions in the upper cervical spine after whiplash injury using MRI. In the spinal segments C 0-1 and C 1-2 MRI functional diagnosis showed clear advantages compared to X-ray diagnosis. Apart from data about the normal course of movement in these joints it was possible to classify and reproduce malfunctions exactly. The malfunctions diagnosed can be found in normal volunteers as well, so that in an evaluation no causal link between the very existence of a malfunction and the complaints can be established.

[Earache and functional disorders of the cervical spine]

The importance of the cervical spine in routine ENT practice is discussed, using the example of otalgia due to disorders of the cervical vertebra: Evaluation and follow-ups of 13,000 patients showed that 6% had diseases caused by the cervical spine. Frequency, pathophysiology and treatment results of cervicogenic otalgia are presented. The principles of adequate functional diagnostics and therapy of cervical spine disorders are explained.

Three-dimensional motion of the upper cervical spine in rheumatoid arthritis

Rheumatoid arthritis frequently contributes to instability of the upper cervical spine. Rotational instability of the upper cervical spine was evaluated in rheumatoid arthritis patients using biplanar x-ray photogrammetry. Three-dimensional cervical motion and the instantaneous axis of rotation of the atlas relative to the axis were evaluated in normal and rheumatoid arthritis patients during axial rotation in the horizontal plane. Anterior atlantoaxial subluxation did not increase during axial head rotation in either the atlantoaxial subluxation or the vertical subluxation groups, while the instantaneous axes of rotation were distributed posteriorly in the dens in the RA-normal group, but were widely scattered in the atlantoaxial subluxation group.

A new appraisal of abnormalities of the odontoid process associated with atlanto-axial subluxation and neurological disability

It is well known that abnormalities of the odontoid process may be associated with subluxation and neuraxial compression. Modern computerized imaging is demonstrating that existing classifications are in need of revision since they no longer reflect current views on development, nor do they adequately explain the patterns of abnormality commonly encountered in clinical practice. This study is a description of 62 varied clinical cases examined by high definition computerized myelography or MRI in flexion and extension, some before and after stabilization procedures. From these descriptions, and a review of the old and more recent literature concerning phylogenesis and ontogenesis of the odontoid, the following conclusions were drawn. The dens within the atlas ring is not morphologically a centrum of the first cervical vertebra, but a projection arising from it. In os odontoideum the dens forms normally, but ossifies abnormally because of abnormal motion; it is a result rather than the cause of instability. Hypoplasia of the dens is usually incorrectly diagnosed. When present it is associated with atlanto-occipital assimilation, fusion of the second and third, or more, cervical vertebrae, loss or reduction in axial rotation of the head, basilar invagination and hindbrain deformity of Chiari type. Therefore it is part of a regional anomaly involving hypoplasia of the derivatives of the occipital and upper cervical somites. Recognition of these aspects simplifies both diagnosis and the formulation of therapeutic strategies for different types of clinical presentation.

In vivo kinematics of the cervical spine. Part I: Development of a roentgen stereophotogrammetric technique using metallic markers and assessment of its accuracy

A technique for simultaneous roentgen stereophotogrammetry (RS) was developed, and its accuracy was assessed. In vitro models fabricated from dried cadaveric C4 and C5 vertebrae were used to simulate the motion behavior of the cervical spine. Metallic markers made of Vitallium beads (diameter < 0.3 mm) were implanted into the posterior and anterior surfaces of each vertebra at surgically accessible locations to simulate the bead placement for both posterior and anterior surgical approaches to the cervical spine. A series of roentgen stereo pairs were obtained to systematically assess the accuracy (validity) of displacement measurements in anteroposterior (AP) translation, axial rotation, and flexion/extension. In addition, the effects of soft tissue density on the accuracy of the system were investigated by obtaining a series of roentgen stereo pairs with the experimental model immersed in a water bath. The coordinates of the metallic markers on the radiographs were then digitized by two raters who were not informed of the actual motion (i.e., blind study). The results indicated a high accuracy throughout the study. Overall root mean square errors were 0.07 mm for AP translation, 0.08 degrees for axial rotation, and 0.14 degrees for flexion/extension. The corresponding accuracy estimates (R2 values by linear regression analysis) were very high (0.992, 0.998, and 0.995) when the measurement results were compared with the actual displacements. The water bath did not affect measurement accuracy, indicating that soft tissue density should have little effect on the accuracy of the technique for in vivo applications. This system appears to be an accurate and reliable method for assessment of simulated in vivo cervical spine motion, regardless of the rater. The technique has been further used in in vivo assessment of cervical spine kinematics in one patient to confirm the efficacy of the developed technique.

Os odontoideum: chronic neck pain after car accident; failure of two posterior atlantoaxial arthrodeses--medicolegal issues in the occupational setting

OBJECTIVE

To present the case of a woman with previously asymptomatic os odontoideum (OO) who developed chronic neck pain after a car accident.

CLINICAL FEATURES

A 32-yr-old woman developed slight constant neck pain following a car accident. Radiographs revealed OO with 12-mm atlantoaxial subluxation on neck flexion. There was no spinal cord compression clinically or on magnetic resonance imaging.

INTERVENTION AND OUTCOME

Posterior atlantoaxial arthrodesis was performed twice but the bone graft resorbed for no apparent reason. The patient was treated with analgesics, physiotherapy and a Philadelphia collar to prevent accidental spinal cord compression.

CONCLUSION

OO patients may remain asymptomatic if "space available for cord" is sufficient. Even low velocity rotational injury can precipitate chronic neck pain in adults with OO. Posterior atlantoaxial arthrodesis can fail inexplicably even under the best circumstances. Medicolegal issues in the occupational setting are discussed.

Neurologic involvement in patients with rheumatoid arthritis with atlantoaxial subluxation--a clinical and neurophysiological study

Anterior subluxation of the atlantoaxial joint (AAS) is a frequent and potentially serious complication of rheumatoid arthritis (RA). The results of neurological evaluation, obtained in 30 patients with RA with AAS, and of somatosensory evoked potentials (SEP) studies, accomplished in 25 of these patients, were compared with the findings observed in 20 patients with RA without AAS, all of whom underwent neurological evaluation and SEP studies. Abnormal plantar responses were found only in patients with RA with AAS. There were more frequent SEP abnormalities in patients with RA with AAS than in patients without AAS, namely increased latencies of the N13 potentials evoked by stimulation of the median and radial nerves, which correspond to conduction delays at the cervical spinal cord level. A sensitivity of 56% and a specificity of 90% for SEP studies in the diagnosis of AAS in patients with RA were found. On the other hand, the observation that the mean values for the latencies of the N11 and N13 potentials evoked by stimulation of the radial nerves were significantly higher in patients with RA with AAS compared to patients with RA without AAS may suggest the existence of a frequent subclinical involvement of the cervical spinal cord caused by AAS.

Somatosensory and brainstem auditory evoked potential in congenital craniovertebral anomaly; effect of surgical management

Clinical features and evoked potential recordings were analysed in 32 patients with congenital atlantoaxial dislocation before and after surgery. Seven patients (group 1) had atlantoaxial dislocation, while 22 patients had associated basilar invagination (group 2). In both groups, pyramidal tract signs, posterior column signs, wasting of the upper limbs, and abnormality of somatosensory evoked potentials (SSEP) were similar. Conversely, lower cranial nerve involvement and abnormal brainstem auditory evoked potentials (BAEP) were significantly more in patients with basilar invagination (p less than 0.05). All seven patients in group 1 and 17 patients in group 2 were operated upon. Clinical and electrophysiological deterioration were significant in patients with basilar invagination (group 2), following posterior fixation compared with group 1. Among the patients in group 2, who clinically deteriorated following posterior fixation, seven had transoral excision of odontoid and six of them improved both clinically and electrophysiologically. Two patients in group 2 had odontoid excision before posterior fixation, and in both the evoked potentials improved postoperatively. In group 1 the patient's BAEP remained unaffected following posterior fixation, however, in group 2, eight patients over 53% showed improvement in brainstem function following posterior fixation. This study shows the value of evoked potentials in congenital atlantoaxial dislocation, and rationalizes the surgical procedure in these patients. In patients with basilar invagination, odontoid excision is the preferred first stage procedure.

Biomechanical evaluation of four different posterior atlantoaxial fixation techniques

Four different techniques for posterior atlantoaxial fusion were tested in vitro: 1) wire fixation with one median graft (Gallie type); 2) wire fixation with two bilateral grafts (Brooks type); 3) transarticular screw fixation (Magerl); and, 4) two bilateral posterior clamps (Halifax). The experiment was designed to determine the immediate three-dimensional stability of the spinal construct. Ten fresh human cadaveric specimens were tested intact, injured, and instrumented with each of the fixation techniques. The injury consisted of a severe soft tissue injury model, in which the alar, transverse, and capsular ligaments were transected. The three-dimensional motions of C1 relative to C2 were measured as the specimens were subjected to loads of pure moments in flexion-extension, axial rotation, and lateral bending. Each fixation technique significantly decreased motion in all directions, as compared to the intact and injured spines. We found that the Gallie system generally allowed significantly more rotation in flexion, extension, axial rotation, and lateral bending than the other three fixation techniques. There was generally no significant difference between the amount of rotation with the other three fixation techniques. However, the Magerl technique tended to allow the least rotation. The anteroposterior translation of two points on C1 were about equal for all fixation techniques.

[Therapy of functional disorders of the craniovertebral joints in vestibular diseases]

Cervicogenic vertigo is caused by functional disorders of the craniovertebral joints. Improvement of vertigonous symptoms by chiropractic treatment was often described. The therapeutic effect of chiropractic treatment in 28 patients with vertigo and purely functional disorders of the upper cervical spine or with a combination of functional disorders of the upper cervical spine and the labyrinth was evaluated. Improvement of vertigonous symptoms on patients with purely functional disorders of the craniovertebral joints as well as on patients with combined functional disorders of the craniovertebral joints and labyrinth could be seen. Two of the 28 patients showed persistent relief of symptoms and normalisation of cervical motility whereas the vestibular deficit persisted. One patient with persistent vestibular dysfunction showed recurrent malfunction of the upper cervical spine and vertigo. In our opinion chiropractic treatment is mandatory for the therapy of patients with vestibular affections and functional disorders of the craniovertebral joints.

[Chronic rotational dislocation in the lateral atlanto-axial joint in a seven year old girl]

A case of inveterate, rotational dislocation in the atlanto-axial joint type III in 7 year old girl hit by a car was presented. Direct skull traction was applied resulting in complete reduction and regaining of the full range of motion in the cervical spine.

The effect of flexion-extension movement on vertical atlantoaxial subluxation measurements

Flexion-extension movement and atlantoaxial subluxation (AAS) serve to alter the relations between the anatomical landmarks used in the diagnosis of vertical subluxations. The effects of such alterations are examined here. Lateral view radiographs of the cervical spine taken during flexion and extension were studied in 86 female patients with rheumatoid arthritis, 56 of whom also had AAS. All the methods used (McRae, McGregor, Redlund and Sakaguchi-Kauppi) showed a shift of the mean values in a pathological direction during flexion (p less than 0.001, Sakaguchi-Kauppi: p less than 0.003). The difference between the flexion and extension values (McRae, Redlund, Sakaguchi-Kauppi) correlated with the severity of AAS in flexion (correlation coefficients and p values: 0.403, 0.303 and 0.441, p less than 0.001, p = 0.005, p less than 0.001 respectively). Thus, some vertical movement is connected with AAS during flexion and this should be taken into consideration when weighing treatment options.

[Analysis of radiographic changes in the cervical spine in rheumatoid arthritis]

At the outpatient department of rheumatology 100 patients having definitive or classic rheumatoid arthritis (RA) were examined and their cervical spine was radiographed with traditional X-ray technique. Correlation between roentgen signs and some parameters of the patient and of the disease was processed by regression analysis. The presence of the rheumatoid factor and second line drug therapy did not influence radiographic changes. Degenerative roentgen signs showed a linear correlation with the RA functional capacity and the duration of cervical complaints, and an exponential correlation with the duration of disease and the age of the patient. There was a linear correlation between osteoporosis and all the parameters examined. Inflammatory radiographic changes showed an exponential correlation with functional capacity and duration of cervical complaints, and a linear correlation with the duration of illness and the age of the patient. Symptoms of patients never treated with steroids was more severe than of those receiving short steroid therapy, but less serious than of those who had taken steroids for a long time (for longer than 10 years).

Os odontoideum with posterior atlantoaxial instability

Nine patients who had os odontoideum with posterior atlantoaxial instability are reviewed. Three parameters were measured on the lateral radiographs: the distance from the os odontoideum to the spinous process of the axis in extension (Dext), the distance from the os odontoideum to the posterior arch of the atlas (Datl), and the degree of instability (Inst). Patients were classified into four groups: Group I, local symptoms (N = 3); Group II, transient myelopathy (N = 0); Group III, progressive myelopathy (N = 6); and Group IV, cerebral symptoms (N = 0). The development of cervical myelopathy was not related to degree of instability but to distance from the os to the spinous process of the axis (Dext). Dext was more than 16 mm in Group I and less than or equal to 16 mm in Group III. Five of six patients in Group III underwent myelography. Based on myelographic findings, Group III was further subdivided into two groups, Group IIIA (N = 2) and Group IIIB (N = 3), according to the following characteristics: In Group IIIA, the distance from the os to the posterior arch of the atlas was more than 13 mm, and the spinal cord was impinged between the os odontoideum and the lamina of the axis in extension and reduced in flexion. In Group IIIB, Datl was less than or equal to 13 mm, and the spinal cord was compressed at the level of the atlas during flexion and extension. Stenotic Datl of 13 mm or less specifically defined severe cervical myelopathy. Surgical treatment for cervical myelopathy in os odontoideum with posterior instability is suggested as follows: in the absence of canal stenosis of the atlas (Group IIIA), atlantoaxial fusion in a reduced position is indicated; when associated with canal stenosis of the atlas (Group IIIB), laminectomy of the atlas followed by occiput-to-C2 arthrodesis is indispensable.

Atlantoaxial mobility after screw fixation of the odontoid: a computed tomographic study

Between 1979 and 1989, anterior screw fixation of the odontoid process was performed in 16 patients with fractures of the odontoid. One patient died suddenly 2 days after the operation. Postmortem examination could not disclose the cause of death. No other complication was noted. We followed 13 patients. At examinations 7 to 82 months after injury, all fractures were consolidated in reduced position. In all patients, a functional computed tomographic (CT) examination of the atlantoaxial rotation was performed. Atlantoaxial rotation measurement ranged from 7 to 38 degrees to the right (average: 25.2 degrees) and 7 to 41 degrees (average: 24.1 degrees) to the left side. Five patients presented a normal range of atlantoaxial rotation, 29 to 41 degrees; 3 had a rotation of 20 to 28 degrees; 3 a rotation of 10 to 20 degrees; and in 2, rotation was less than 10 degrees to one side. Our results suggest that anterior screw fixation is the therapy of choice for Type II and cephalad Type III dens fractures. However, significant complications have been reported by other authors. Therefore, a careful surgical technique is mandatory, and contraindications should be respected.

Flexion, extension, and lateral bending of the upper cervical spine in response to alar ligament transections

The purpose of this in vitro experimental study was to determine the role of alar ligaments in providing flexion, extension, and lateral bending stability to the upper cervical spine. Ten fresh human cadaver specimens occiput-C3 were studied in a complete unconstrained and three-dimensional manner, first intact and then after sequential cutting of the left and right alar ligaments. At the C0-C1 joint, there were increases in flexion motion with sequential cutting of the alar ligaments but none in extension. For the same joint, cutting of the left alar ligament resulted in a significant increase in neutral zone in right lateral bending but not in left lateral bending, whereas there were no significant increases in the ranges of motion. At the C1-C2 joint, there were significant increases both in flexion and extension due to cutting of the left alar ligament, but subsequent cutting of the right alar ligament resulted in a small increase for flexion only. At this joint, right lateral bending increased due to cutting of the left alar ligament, but the same was not true for the left lateral bending. Subsequent cutting of the right alar ligament resulted in significant increases for both the right and left lateral bending.

[Instability in injury of the alar ligament. A biomechanical model]

Fresh human cadaveric specimens of occiput (C0) to C3 were subjected to 1.5 nm of flexion, extension and bilateral bending and axial torque. The resulting physiological motions were studied in an unconstrained three-dimensional manner. The effects of sequential transections of the left and right alar ligaments on the relative motion of C0-1 and C1-2 were studied. After transection of the left alar ligament, the percentage increases in neutral zones (NZ) and ranges of motion (ROM) were documented at both the C0-1 and C1-2 joints. In the sagittal plane, the most increase was at C1-2 due to the flexion moment, e.g., 47.4% in NZ and 27.6% in ROM. In lateral bending, the left alar transsection resulted in mostly right lateral bending increases and at the C0-1 joint, 37.1% in NZ and 19.6% in ROM. In axial rotation, changes in the total motion of the C0-2 joint complex were more reliable indicators. For left alar transsection, most increases were in right axial rotation, e.g., 25.6% for right rotation versus 11.2% for left rotation in the NZ parameter. Functional loss of the alar ligaments indicates a potential for instability which, however, must be determined in conjunction with other clinical findings, such as neurological dysfunction, pain and deformity.