Intended and non-intended kinematic effects of atlanto-axial rotational high-velocity, low-amplitude techniques

INTRODUCTION

The study of neck kinematics during high-velocity, low-amplitude manipulations of the atlanto-axial segment is essential to understanding cervical motion mechanisms and their impact and possible risk for soft-tissue injuries during treatment of spine disorders.

METHODS

Twenty fresh-frozen specimens were tested during manual application of an axial rotation technique.

FINDINGS

The kinematics indicate the thrust induced motion components of approximately 1° at the treated segment around all three axes of the local embedded reference frame. Moreover, an equal amount of axial rotation motion took place at the adjacent atlanto-occipital joint.

INTERPRETATION

Overall atlanto-axial motion remained below the level of slow regional mobilization of the cervical spine. These findings can be correlated to literature data concerning the limited increase in vertebral artery strain during high-velocity, low-amplitude manipulation.

Case report: nonoperative treatment of an unstable Jefferson fracture using a cervical collar

The treatment of unstable burst fractures of the atlas (Jefferson fractures) is controversial. Unstable Jefferson fractures have been managed successfully with either immobilization, typically halo traction or halo vest, or surgery. We report a patient with an unstable Jefferson fracture treated nonoperatively with a cervical collar, frequent clinical examinations, and flexion-extension radiographs. Twelve months after treatment, the patient achieved painless union of his fracture. The successful treatment confirms prior studies reporting unstable Jefferson fractures have been treated nonoperatively. The outcome challenges the clinical relevance of treatment algorithms that rely on the "rules of Spence" to guide treatment of unstable Jefferson fractures and illustrates instability may not necessarily be present in patients with considerable lateral mass widening. Additionally, it emphasizes a more reliable way of assessing C1-C2 stability in unstable Jefferson fractures is by measuring the presence and extent of anterior subluxation on lateral flexion and extension views.

Screw fixation via diploic bone paralleling to occiput table: anatomical analysis of a new technique and report of 11 cases

Several types of posterior approaches have been adopted for occipitocervical fusion. Prior to this study, Foerater et al. in 1927 used a fibular strut graft in the site between the occiput and the lower cervical spine to achieve fusion. Since then, various techniques including wrings, Hartshill loop, AO reconstructive plate, and AXIS occipital plate were described and used widely. As far as we know, all these techniques involve the screw placement vertical to the diploic bone; however none has ever addressed the feasibility of screw placement in occiput parallelling to the diploic bone. In our study, 30 dry specimens of human occiputs were measured manually using vernier calipers and protractors. The intradiploic screw was first supposed to be inserted inferiorly to the superior nuchal line (SNL) prominence. The entry point located at the superior edge of the SNL prominence. Afterward, the measurements of extracranial occiput in SNL area on midline and bilateral 15 mm to the midline saggital-cutting planes of the occiput were conducted. The thickness of the occipital bone at the location of SNL prominence, the entry point, the exit point and the screw orientation were measured, respectively. Afterward, 11 patients with craniocervical malformation were treated surgically using this alternative and their X-ray radiographs and CT scans were evaluated postoperatively. The data showed that the occipital at the site of SNL prominence was the thickest. The thickest point was external occipital protuberance (EOP), which was up to 14 mm. The thickness decreased gradually from the site of SNL to the superior border of surgical decompressed area. The actual length of screw channel was about 26 mm. The mean thickness for safe screw insertion ranged from 5.73 to 14.14 mm. A total of 22 intraocciput screws parallel to diploic bone were placed precisely, without injury to the cerebral and inner occipital venous sinus. The results confirm that occiput is available for holding intraocciput screw paralleling to diploic bone.

A detailed morphologic and functional magnetic resonance imaging study of the craniocervical junction in adolescent idiopathic scoliosis

STUDY DESIGN

Conventional and phase-contrast magnetic resonance (MR) imaging were used to evaluate the morphology and cerebrospinal fluid (CSF) flow dynamics at craniocervical junction in adolescent idiopathic scoliosis (AIS).

OBJECTIVES

To determine the morphology of cerebellar tonsil, foramen magnum, and dynamic flow of CSF at the craniocervical junction in AIS patients versus normal controls and their correlation with somatosensory cortical evoked potentials (SSEP).

SUMMARY OF BACKGROUND DATA

Previous studies have documented obstructed CSF flow in patients with Chiari I malformation. Low-lying cerebellar tonsils and syringomyelia are also observed in AIS patients. We sought to investigate whether disturbed CSF flow is also evident in AIS subjects at the foramen magnum level and its association with level of cerebellar tonsils and dimensions of foramen magnum.

METHODS

Conventional and phase-contrast MR were performed in 105 adolescent girls (69 AIS subjects and 36 age-matched controls). Measurements of cerebellar tonsillar level related to the basion-opsithion (BO) line, anteroposterior (AP), transverse (TS) diameter, and area of foramen magnum, and peak velocity of CSF flow in both the anterior and posterior subarachnoid space through foramen magnum were obtained. Correlations were made among different parameters and SSEP findings.

RESULTS

A total of 42% of subjects in the AIS group had the cerebellar tonsillar tip positioned 1 mm below the BO line. The cerebellar tonsillar level in AIS subjects was significantly lower than the median tonsillar level in normal controls (P < 0.01). The AP diameter and area of foramen magnum were significantly larger in AIS subjects when compared with normal controls (P < 0.05), but the peak CSF velocities through foramen magnum showed no significant difference (P > 0.05).

CONCLUSION

Peak CSF velocities through foramen magnum were not significantly different in AIS subjects despite the presence of low-lying cerebellar tonsils. This might be explained by the compensatory effect of larger foramen magnum in AIS subjects.

Using peripheral stimulation to reduce the pain of C2-mediated occipital headaches: a preliminary report

BACKGROUND

Peripheral nerve stimulation (PNS) is an accepted treatment for neuropathic pain. Recent studies have focused on its potential for relieving headache pain.

OBJECTIVES

To investigate the effectiveness of PNS in reducing occipital headache pain.

DESIGN

A prospective, 12-week pilot study involving 11 patients evaluated before and after implantation of PNS systems to treat C2-mediated occipital headaches.

METHODS

Prior to and at 4 and 12 weeks after implantation, patients completed the Short-Form McGill Pain Questionnaire (SF-MPQ), Visual Analog Scale (VAS), and Present Pain Index (PPI). Patients also answered questionnaires and kept diaries to record stimulator use, medication consumption, and numbers of headaches.

RESULTS

A comparison of pre- and post-implantation evaluations showed statistically significant declines in scores on the SF-MPQ (64%; p = 0.0013), VAS (67%; p < 0.0001), and PPI (68%; p = 0.0009). Most patients (91% and 64% respectively) reported reductions in medication use and numbers of headaches. Patients also reported a reduction in headache symptoms and the impact of headaches on activities. Two adverse events were encountered, one due to a loose connection and, the other caused by lead migration.

CONCLUSIONS

PNS reduced headache pain, headache frequency and medication use.

Atlas vertebra realignment and achievement of arterial pressure goal in hypertensive patients: a pilot study

Anatomical abnormalities of the cervical spine at the level of the Atlas vertebra are associated with relative ischaemia of the brainstem circulation and increased blood pressure (BP). Manual correction of this mal-alignment has been associated with reduced arterial pressure. This pilot study tests the hypothesis that correcting mal-alignment of the Atlas vertebra reduces and maintains a lower BP. Using a double blind, placebo-controlled design at a single center, 50 drug naïve (n=26) or washed out (n=24) patients with Stage 1 hypertension were randomized to receive a National Upper Cervical Chiropractic (NUCCA) procedure or a sham procedure. Patients received no antihypertensive meds during the 8-week study duration. The primary end point was changed in systolic and diastolic BP comparing baseline and week 8, with a 90% power to detect an 8/5 mm Hg difference at week 8 over the placebo group. The study cohort had a mean age 52.7+/-9.6 years, consisted of 70% males. At week 8, there were differences in systolic BP (-17+/-9 mm Hg, NUCCA versus -3+/-11 mm Hg, placebo; P<0.0001) and diastolic BP (-10+/-11 mm Hg, NUCCA versus -2+/-7 mm Hg; P=0.002). Lateral displacement of Atlas vertebra (1.0, baseline versus 0.04 degrees week 8, NUCCA versus 0.6, baseline versus 0.5 degrees , placebo; P=0.002). Heart rate was not reduced in the NUCCA group (-0.3 beats per minute, NUCCA, versus 0.5 beats per minute, placebo). No adverse effects were recorded. We conclude that restoration of Atlas alignment is associated with marked and sustained reductions in BP similar to the use of two-drug combination therapy.

Intraoperative dynamic angiography to detect resolution of Bow Hunter's syndrome: Technical case report

BACKGROUND

Bow Hunter's syndrome is a rare form of vertebrobasilar insufficiency that may be successfully treated by surgical intervention. Use of intraoperative dynamic transcranial Doppler ultrasound for surgical treatment of vertebrobasilar insufficiency has been described in literature. However, this technique was inconsistent and unreliable in some patients. We present a case of a patient with Bow Hunter's syndrome treated surgically and emphasize the valuable addition of intraoperative dynamic angiography to determine resolution of vertebral artery compromise.

CASE DESCRIPTION

The patient was a 58-year-old man with complaints of dizziness, vertigo, and near-syncopal episodes that occurred when he rotated his head to the left. Imaging revealed compromise of the dominant left vertebral artery with leftward head rotation. An anterior cervical approach with decompression of the left subaxial vertebral artery was performed. Significant osteophyte formation was observed. Removal of bone and decompression of the vertebral artery was performed. Intraoperative dynamic angiography confirmed resolution of vertebral artery compression and minimized the amount of decompression. No further intervention was required.

CONCLUSION

Intraoperative dynamic angiography is a definitive test to determine hemodynamic resolution of Bow Hunter's syndrome. It offers real-time feedback of vertebral artery decompression, potentially minimizes the amount of decompression, and can be performed safely.

Rotational vertebral artery syndrome: oculographic analysis of nystagmus

In four patients with rotational vertebral artery syndrome (RVAS), the initial nystagmus was mostly downbeat, with the horizontal and torsional components beating toward the compressed vertebral artery side (n = 3) or directed away (n = 1). Three patients showed spontaneous reversal of the nystagmus and two exhibited no or markedly diminished responses on immediate retrial of head rotation (habituation). The patterns of nystagmus suggest that RVAS may result from differing mechanisms.

Palpatory diagnosis of plagiocephaly

INTRODUCTION

The term plagiocephaly, from the Greek plagios (oblique) and kephalê (head), means distortion of the head, and refers clinically to cranial asymmetry. Cranial Osteopathy, since it was first proposed, has focussed upon the diagnosis and treatment of birth trauma and cranial asymmetries, and consequently specific therapy for plagiocephalic deformities has been described. Osteopathic manipulation also has been proposed as a treatment for torticollis, a condition associated with plagiocephaly. For these reasons, we decided to look at the mechanics of the occipital bone and the adjacent atlas and bones of the cranial base, in relation to functional plagiocephaly.

METHODS

The records of 649 children seen in an osteopathic practice in Lyon, France, were reviewed retrospectively, in compliance with the legal requirements of the Commission Nationale de l'Informatique et des Libertés (CRIL) and the Helsinki accord, for gender, age at presentation, birth history, obstetrical data (breech presentation, vacuum extraction, forceps delivery or Caesarean section), presenting complaint, side of posterior plagiocephaly, side of frontal plagiocephaly, torticollis, motion pattern of the occipital bone upon the atlas, and motion pattern of the spheno-occipital synchondrosis.

RESULTS

We found significant correlations between plagiocephaly (right/left) and primipara (P=0.024), use of forceps (P=0.055) and extractor suction (P=0.055). Correlations were also found between flattening of the occiput (right/left) and lateral strain of the spheno-occipital synchondrosis (P=0.002) and between plagiocephaly (right/left) and occipito-atlantal motion (P=0.000).

CONCLUSION

We found a significant correlation between the lateral strain pattern of the spheno-occipital synchondrosis and plagiocephaly and between rotational dysfunction of the occiput upon the atlas and the side of posterior plagiocephaly. We suggest that thorough neonatal osteopathic examination can identify individuals predisposed to develop posterior plagiocephaly.

Why Atlas, why not Heracles: reflections on the rheumatoid cervical spine

Rheumatoid involvement of the 24 joints of the cervical spine leads to prominent changes in the occipito-atlanto-axial area. Eight different subtypes of such changes are recognized, depicted, and defined. The frequencies of these 8 subtypes in rheumatoid arthritis and other arthritides are tabulated. A central role in these disorders is played by a small-size, heavy-duty fitting piece or adapter, atlas, between the occiput and C2. The history of the fate of Atlas, who led the fight of godlike titans against the new gods of Olympos, is recapitulated. In particular, for a short moment Atlas was released from his heavy physical ordeal by another strongman, the heavy-weight wrestler of his times, Heracles. The reasons for the current nomenclature and answer to the question "Why Atlas, why not Heracles" are provided.

Cervical angina caused by atlantoaxial instability

Cervical angina is defined as a paroxysmal precordialgia that resembles true cardiac angina caused by cervical spondylosis. Cervical angina most commonly results from compression of the C7 ventral root. We present here a case of cervical angina caused by atlantoaxial instability. This case had marked atlantoaxial instability but no flexibility of the middle to lower levels of the cervical spine. Although there was mild C7 root compression on the radiologic findings, the chest pain was induced by neck motion, and the precordialgia disappeared after posterior atlantoaxial fusion without C7 root decompression. Therefore, we diagnosed this case as cervical angina caused by spinal cord compression at the C1-C2 level. It was speculated that a perturbation of the sympathetic nervous system or a hypofunction of the pain suppression pathway in the posterior horn of the spinal cord caused the pectoralgia. Although cervical angina is a rare disease, physicians should be aware of it; if there are no abnormal findings on cardiac examinations for angina pectoris, they should examine the cervical spine. Cervical angina due to atlantoaxial instability is one of the differential diagnoses of precordialgia.

Finite element model of the Jefferson fracture: comparison with a cadaver model

This study tries to explain the reason why the Jefferson fracture is a burst fracture, using two different biomechanical models: a finite element model (FEM) and a cadaver model used to determine strain distribution in C1 during axial static compressive loading. For the FEM model, a three-dimensional model of C1 was obtained from a 29-year-old healthy human, using axial CT scans with intervals of 1.0 mm. The mesh model was composed of 8200 four-noded isoparametric tetrahedrons and 37,400 solid elements. The material properties of the cortical bone of the vertebra were assessed according to the previous literature and were assumed to be linear isotropic and homogeneous for all elements. Axial static compressive loads were applied at between 200 and 1200 N. The strain and stress (maximum shear and von Mises) analyses were determined on the clinically relevant fracture lines of anterior and posterior arches. The results of the FEM were compared with a cadaver model. The latter comprised the C1 bone of a cadaver placed in a methylmethacrylate foam. Axial static compressive loads between 200 and 1200 N were applied by an electrohydraulic testing machine. Strain values were measured using strain gauges, which were cemented to the bone where the clinically relevant fracture lines of the anterior and posterior arches were located. As a result, compressive strain was observed on the outer surface of the anterior arch and inferior surface of the posterior arch. In addition, there was tensile strain on the inner surface of the anterior arch and superior surface of the posterior arch. The strain values obtained from the two experimental models showed similar trends. The FEM analysis revealed that maximum strain changes occurred where the maximum shear and von Mises stresses were concentrated. The changes in the C1 strain and stress values during static axial loading biomechanically prove that the Jefferson fracture is a burst fracture.

Transoral resection of retro-odontoid disc sequestration: case report and review of the literature

A rare case of retro-odontoid disc sequestration causing significant cord compression and progressive neurological deterioration is presented. The clinical history, radiology, treatment and pathogenesis of the case are described, along with a review of the relevant literature.

A biomechanical study of Jefferson fractures

STUDY DESIGN

Fifteen specimens of the first cervical vertebra were tested by the application of pure tensile forces to failure. Seven specimens had intact transverse ligaments, and eight had transection of the transverse ligament before testing. Specimens were tested to failure by the rapid application of laterally directed tensile force to the ring; this force then was exerted through the lateral masses to simulate the mechanism of injury for this fracture as proposed by Jefferson.

OBJECTIVES

To measure the biomechanical characteristics of the C1 ring, including the fracture patterns created with tensile loading, and to describe the influence of the transverse ligament on the behavior of the ring as it failed under tension.

SUMMARY OF BACKGROUND DATA

Jefferson fractures have been reproduced in the laboratory by subjecting head and neck preparations to axial load. However, no previous detailed biomechanical studies of the fracture characteristics of the isolated C1 vertebra have been reported.

METHODS

Specimens were tested to failure by rapid application of laterally directed tensile forces to the ring.

RESULTS

Eleven two-part and three three-part fractures occurred. The mean tensile strength of the atlas was found to be 2,280 N. The average deformation required to fracture the C1 ring was 1.57 mm. The total energy absorbed by the ring averaged 1.99 N-m. There was no statistically difference between those specimens with the transverse ligament intact and those without a transverse ligament.

CONCLUSIONS

The results of this study show that fractures of the C1 ring of greater than two parts can occur with pure tensile loading. The ring will fracture with as little as 1 mm of deformation.

Indications for surgery in upper cervical spine injury

20% of all spine injuries are cervical spine injuries. Surgical treatment of these injuries must take into account the great mobility of this part of the spinal column. Therefore, biomechanical aspects must be considered, especially in the upper cervical spine-C1 and C2. Describing our own therapeutical regimen in 35 patients with unstable upper cervical spine injuries we explain the biomechanical back-ground and review the literature. It becomes evident that ventral approaches are superior to dorsal techniques for decompression, reposition, and stabilization with minimal loss of mobility.

Spinal cord compression caused by ossification of the transverse ligament of the atlas

Although ossification of the posterior longitudinal ligament and ligamentum flavum are well known, ossification of the transverse ligament of the atlas is extremely rare. We present the case of a 79-year-old man who developed a gradually progressive spastic quadriparesis caused by upper cervical canal stenosis due to ossification of the transverse ligament of the atlas together with ligamentum flavum hypertrophy.

Multidirectional instabilities of experimental burst fractures of the atlas

For the purpose of understanding the acute instability of a burst (Jefferson) fracture of the atlas, the authors produced the fractures experimentally and measured multidirectional flexibilities in seven cadaveric C0-C3 specimens. The flexibilities were measured by the authors' standardized method: they applied six types of physiologically pure moments (up to 1.5 Nm) and recorded the ensuing C0-C2 motions by stereophotogrammetry. The flexibility tests were performed before and after the production of the fracture. The greatest increase in flexibility due to the injury was in flexion-extension (+22.0 degrees, 41.7%). In lateral bending, the increase was 7.7 degrees, or 23.9%. The flexibility was mostly maintained in axial rotation (+4.8 degrees, 5.4%). The increase in motion was due to an increase in neutral zone in flexion-extension, and an increase in the elastic zone in lateral bending. These flexibility results of experimentally produced fractures reflect quite well the acute instabilities seen clinically.

Assimilation of the atlas with associated syringomyelia and Chiari 1 malformation (Klippel-Feil type 2)

This case report describes an unusual congenital anomaly of the craniovertebral junction in a 14 year old male. Cervical radiographs showed the bony anomaly, while thin slice CT (with 2-D and 3-D reformations), MR imaging, and angiography were particularly useful in accurately assessing the bony, soft tissue and vascular anatomy, prior to and following surgery.

Experimental study of atlas injuries. II. Relevance to clinical diagnosis and treatment

Atlas injuries were produced in vitro and evaluated by radiographic examinations and anatomic studies from a clinical viewpoint. Ten cadaveric human upper cervical spine specimens were subjected to a high-speed axial impact. Injuries to the atlas consisted of six bursting fractures, two ruptures of the transverse ligament, one four-part fracture without a prominent bursting, and one posterior arch fracture. The major soft tissue injury involved the transverse ligament. There were five bony avulsions and three midsubstance tears. In this study, computed tomographic examinations clearly demonstrated the sites of fracture and bony avulsions of the transverse ligament. The best diagnostic tool for function of the transverse ligament was determined to be the atlantodental interval on flexion radiographs. Axial traction force reduced a bursting fracture of the atlas ring. The in vitro atlas injury model gives useful information for clinical diagnosis and treatment.

Experimental study of atlas injuries. I. Biomechanical analysis of their mechanisms and fracture patterns

Understanding injury mechanisms is important for the prevention, diagnosis, and treatment of spinal injuries. Using 10 fresh cadaveric human spine specimens of occiput to C3, clinically similar injuries of the atlas (C1) were produced with high-speed (4.4 m/sec) axial compression. The traumatic event was biomechanically monitored. The resulting injuries were studied with radiography, computed tomography, and a multidirectional instability test. The average compressive failure force was 3,050 N for specimens impacted in neutral posture (n = 437) and 2,100 N for those in extended posture (n = 282). Corresponding values for the impulse were 34.9 Nsec (n = 8.3) and 17.6 Nsec (n = 1.8). Average instability for both groups, as measured by the neutral zone and range of motion, increased by 90% and 44%, respectively, in flexion-extension and 20% in lateral bending, but not in axial rotation. These findings confirm the clinical observations.

[Chiropractic diagnosis of the atlanto-occipital joint with reference to the Palmer-Sandberg-Gutman functional aspects from the traditional medic-radiologic viewpoint]

Owing to joint mechanics, movement of the atlas alone, as envisioned in HIO diagnosis for producing a superior or inferior position, is not possible when the tranverse ligament is intact, since an atlas movement of this kind would necessitate a change in the statics of the dens amounting to kyphosis or lordosis. Only in the superior or inferior position, as defined by Decking and ter Steege, is there a true malposition of the atlas as a result of atlas movement, and this is only possible if the dens assumes a lordotic or kyphotic position. In such cases all the segments of the cervical spine are used to modify dens statics. Aside from this, superior and inferior positions in HIO diagnosis do not represent any pathology requiring treatment, but normal positions of the atlas within a relatively broad physiologic range. In the vast majority of cases, providing the angle of view is horizontal, there are no findings reflecting the current position of the atlas, but rather a finding due to the development of a condyle movement.

CT-functional diagnostics of the rotatory instability of upper cervical spine. 1. An experimental study on cadavers

Twelve specimens of the upper cervical spine were functionally examined by using radiography, cineradiography and computerized tomographic (CT) scan. The range of rotation was measured from CT images after maximal rotations to both sides. The left alar ligament was then cut and the examination repeated. The alar and transverse ligaments could be differentiated on CT images in axial, sagittal, and coronal views. Rotation at occiput-atlas was 4.35 degrees to the right and 5.9 degrees to the left and at atlas-axis it was 31.4 degrees to the right and 33 degrees to the left. After one-sided lesion of the alar ligament, there was an overall increase of 10.8 degrees or 30% of original rotation to the opposite side, divided about equally between the occiput-atlas and the atlas-axis. It is concluded that a lesion (irreversible overstretching or rupture of alar ligaments) can result in rotatory hypermobility or instability of the upper cervical spine.

Orthopedic problems of the shoulder and neck

If one excludes trauma, problems of the neck and shoulder in children are relatively uncommon. Still, the pediatrician or family practitioner should have sufficient familiarity to provide the family with appropriate counseling and referral. This article emphasizes the common problems, but also notes less common conditions that, if unrecognized, may have serious impact on the health and well-being of the child.

[Forms of fracture of the dens axis in the application of ventral flexion force]

In fracture experiments in 220 cast models of the axis and atlas, an attempt was made to separate two different factors influencing the position of the dens fracture (superior and inferior type): the direction of the force application and the inclination of the dens axis. For this purpose, two extreme forms of dens inclination in the sagittal plane were used, namely a form with a ventrally inclined axis (kyphotic form) and a dorsally oriented axis (lordotic form). The force was applied in ventral flexion in 11 single steps between 10 and 75 degrees. The fracture types occurring under natural conditions could be reproduced with this experimental paradigm. Depending on the direction of the force application, both types of dens fracture occurred in ventral flexing traction alone. Independent of the inclination of the dens axis, this ventral flexion led to an inferior fracture type with a shallow angle, and a superior fraction type with a steep angle. With 75 degrees flexion, no longer the dens fracture, but the Hangman's fracture was the usual fracture type in both dens forms. With fundamental agreement of both dens forms with regard to the direction-dependent genesis of the fracture pattern, the lordotic dens and kyphotic dens displayed differences in the details which are discussed exhaustively. In this connection, the differences in the size of the horizontal thrust component due to the primary form of the dens with the same direction of force application is pointed out. According to the present investigations, a classification of dens fractures should be made more precise by specification of the dens form.

Torticollis in children caused by congenital anomalies of the atlas

Hemi-atlas is a rare congenital anomaly in the formation of the first cervical vertebra. It may cause a rather severe and progressive torticollis. When a child is young, the neck, despite the deformity, is flexible and the torticollis can be passively corrected. However, in some patients it becomes increasingly severe and fixed. I describe the findings in seventeen patients, seven of whom were operated on between 1975 and 1983. Treatment with a brace was shown to be ineffective. In patients with severe deformities, fusion of the upper part of the cervical spine is recommended. Fusion was obtained in all seven patients in whom it was attempted, and there was good postural correction in all. Early operation is recommended if the deformity is increasing. Gradual correction in a halo cast followed by posterior fusion is recommended as the treatment of choice in patients with severe torticollis.

Chronic atlanto-axial instability in Down syndrome

We studied the radiographs of thirty-two patients with Down syndrome for evidence of atlanto-axial instability. One of the patients had instability in 1970 and seven had it in 1983. The interval between the atlas and the odontoid process in the patients who demonstrated motion at that interval radiographically averaged 2.78 millimeters in 1970 and 6.93 millimeters in 1983 (p less than 0.005). Four patients whose radiographs showed atlanto-axial motion in 1970 lost that motion by 1983, and in seven patients who did not show atlanto-axial instability in 1970 it developed by 1983. Atlanto-axial instability was more likely to develop in boys who were more than ten years old. Accessory upper-cervical ossicles became evident in three patients, none of whom had atlanto-axial motion. However, one of these three patients had an abnormally wide atlanto-axial interval.

[Relation between atlas position, prognathism and prognathous jaw anomalies]

The position of the 1st cervical vertebra is investigated in relation to special anomalies of the craniofacial morphology. Two extremely different types like prognathism and progenia are chosen to demonstrate an interdependence. The latter is probably caused by a different head posture which in itself is influenced by the maxillo-facial anomalies. With the aid of the literature the findings can be explained on a functional basis.

Pain arising in the posterior arch of the atlas

Headache of cervical origin is by no means an adequate diagnosis. The exact mechanism has to be established for the case in question. A type of cervical headache which arises from the posteriorr arch of the atlas is described. The basic finding is tenderness of this structure on palpation; the technique of palpation is described. In a majority of cases movement restriction (blockage) between the occiput and the atlase is found. The headache as described by the patient is not characteristic, migrainous attacks being present in about one-third of the cases. A frequent feature is pain on retroflexion of the head. Treatment consists of manipulation of the blockage, and infiltration or needling of the posterior arch of the atlas if there is no blockage or if pain continues after the restoration of mobility. In the more complicated cases remedial exercise is indicated. Experience with 64 cases is described.