Intradiscal pressure recordings in the cervical spine

OBJECTIVE: Experimental investigations analyzing the biomechanics of the cervical spine are less common than similar studies of other regions of the spine. There are no reports on cervical intradiscal pressure (PID) measurements in vitro. We therefore wanted to establish normal values for PID under physiological conditions by simultaneous muscle force simulation. Moreover, the impact of ventral cervical fusion should be elucidated, because in clinical studies, it is a well-known phenomenon that the adjacent segments often show increased degenerative changes. We present a pilot study. METHODS: Seven human cervical spine specimens were tested biomechanically in a specially developed spine tester. Only pure moments were used for flexion/extension, axial rotation, and lateral bending (maximal moment +/- 0.5 Nm). PID was measured simultaneously in C3-C4 and C5-C6. The specimens were tested as intact specimens and after discectomy and fusion in C4-C5. Both test situations were repeated with simulation of muscle forces. RESULTS: We found characteristic load-pressure curves for each of the three motion axes. In neutral position, PID correlated well with former published data from in vivo measurements. After fusion of C4-C5, there was a marked increase of PID in both adjacent segments (e.g., < or = 180% for axial rotation). With muscle force simulation, the increase was even higher (e.g., < or = 400% for axial rotation). CONCLUSION: For the first time, PID could be measured in the cervical spine in an experimental setting. The results obtained using normal specimens under physiological conditions confirmed those reported in two clinical studies. After cervical fusion, a marked increase in PID could be found in both adjacent segments. Presuming that an increase in PID had a negative effect on metabolism of the intervertebral disc, our results may help to explain why progressive degeneration occurs in these segments.     

Sprain of the cervical spine: early functional vs. immobilization treatment

Copper-zinc superoxide dismutase (Cu,Zn-superoxide dismutase) activity was evaluated in lymphocytes and polymorphonuclear cells of insulin-dependent (n = 33) and non-insulin-dependent (n = 34) diabetic patients. A commercial method for the measurement of superoxide dismutase activity was adapted for use on a discrete analyser and evaluated for interference by other antioxidants with superoxide anion-scavenging properties. In comparison to healthy control subjects (n = 32), a significantly lower Cu,Zn-superoxide dismutase activity was found in both lymphocytes and polymorphonuclear cells of insulin-dependent (2.08 +/- 0.58 vs. 1.70 +/- 0.46 U/mg protein, p < 0.05, and 1.06 +/- 0.46 vs. 0.64 +/- 0.40 U/mg protein, p < 0.001, respectively) and non-insulin-dependent diabetic patients (2.08 +/- 0.58 vs. 1.61 +/- 0.48 U/mg protein, p < 0.01, and 1.06 +/- 0.46 vs. 0.53 +/- 0.24 U/mg protein, p < 0.001, respectively). There was a week, but significant negative correlation between age and Cu,Zn-superoxide dismutase activity in lymphocytes and polymorphonuclear cells (r = -0.22 and r = -0.28, p < 0.05, respectively), whereas no influence of gender, diabetes duration and glycaemic control was observed. The results indicate that diabetes mellitus could elicit a significant disturbance in superoxide anion-scavenging potential of lymphocytes and polymorphonuclear cells.     

Symptoms of the cervical spine in temporomandibular and cervical spine disorders

This study was performed to assess the prevalence of signs and symptoms related to cervical spine disorders (CSD) in subgroups of patients with temporomandibular disorders (TMD) and to compare TMD patients and CSD patients with regard to the results of orthopaedic cervical spine tests. One hundred and eleven consecutive patients with TMD and 103 consecutive patients with signs and symptoms of CSD were examined. The results indicated that there is a considerable overlap in the signs and symptoms of patients with TMD and patients with CSD. Signs and symptoms on neck extension occurred more often in CSD patients than in subgroups of TMD patients. No significant differences in upper cervical extension, neck flexion, and shoulder girdle function were found between CSD patients and subgroups of patients with TMD. Patients with CSD reported neck pain during active and passive movements of the neck more often than the subgroups of patients with TMD. TMD patients and CSD patients did not differ with regard to pain on shoulder girdle function and palpation of the shoulder girdle. Logistic regression analyses showed that orthopaedic tests of the cervical spine are of minor importance in discriminating between patients with TMD and patients with CSD. It is concluded that TMD with a myogenous involvement in contrast to TMD with only an arthrogenous involvement should no longer be viewed as a local disorder of the stomatognathic system. The upper quarter, including the stomatognathic system, cervical spine, and shoulder girdle, should be evaluated in patients with more complex or persistent symptoms in the head and neck region.     

Effect of age and loading rate on human cervical spine injury threshold

STUDY DESIGN: Statistical analysis of human cadaver cervical spine compression experiments. OBJECTIVES: To quantify the cervical spine compressive injury threshold as a function of the person's age, gender, and external loading rate. SUMMARY OF BACKGROUND DATA: Results of epidemiologic studies have indicated that most survivors of cervical spinal cord injury have spinal column fractures and dislocations that result from a compression or compression-flexion force vector. Cervical spinal column injury thresholds are dependent on many factors. Delineation of the injury thresholds according to age, gender, and loading rate is necessary to improve clinical assessments and prevention strategies. METHODS: Twenty-five human cadaver head-neck compression tests were included in the analysis. Two statistical models were used to quantify the effects of age, gender, and loading rate on the force required to induce failure in the cervical spine. A multiple linear regression model provided a direct equation that quantified the effects of the variables, and a proportional hazards model was used to quantify probability of injury with each factor. RESULTS: The regression model had a correlation coefficient of 0.87. There was an interactive effect between age and loading rate: Increasing age reduced the effect of loading rate and at approximately 82 years, loading rate had no effect. Men were consistently 600 N stronger than women. The 50% probability of failure for a 50-year-old man at a 4.5-m/sec loading rate was approximately 3.9 kN. Differences in probability curves followed the same trends as seen in the regression model. CONCLUSIONS: The effects of age on cervical spine injury threshold are coupled with the rate of loading experienced through the external force vector that causes the trauma. Assessment of injury mechanisms and thresholds should be based on the person's age, gender, and loading rate to determine treatment and prevent injuries.     

Effect of continuous rotational therapy on intracranial pressure in the severely brain-injured patient

Deoxycytidine kinase activity (dCk) was monitored in cell lines from a rat acute myeloid leukemia model of acquired resistance to cytosine arabinoside (AraC) and decitabine (DAC). In both AraC-resistant cell lines (RCL/A and its subclone RA/7), as well as in a DAC-resistant cell line (RCL/D) which we generated from the drug-sensitive RCL/0 cell line, a total deficiency of dCk activity and a cross-resistance for AraC and DAC was demonstrated. Furthermore, the metabolization of deoxycytidine (dC) was severely impaired in all these cell lines. Km values for dC (9.4 microM in RCL/0 cells) had increased 70- to 100-fold in RCL/D (Km = 673.2 microM), in RCL/A (Km = 947.2 microM) and in RA/7 (Km = 817.5 microM). Vmax values were unaltered in RCL/D and RA/7, and twofold increased in RCL/A. Addition of hydroxyurea (HU) to cell cultures stimulated dCk salvage pathway activity in RCL/0 cells for dC, AraC, and DAC by increasing Vmax values approximately 160% leaving Km constants unchanged. In all resistant cell lines, HU pre-incubation did not influence the level of dCk activity, leaving Km and Vmax values unaltered. These data indicate that deficiency of dCk activity is crucial in the mechanism of drug resistance in this model.     

Athletes with cervical spine injury

Athletic injuries to the cervical spine are infrequent, but can present difficulty in both diagnosis and management. We designed a simple classification system consisting of three broad types of injuries to facilitate management decisions. Also included is a discussion of variations among injuries within each type and recommendations regarding the athlete's return to competition.     

Inflammatory disorders of the cervical spine

The most common inflammatory disorders affecting the cervical spine include adult and juvenile rheumatoid arthritis, ankylosing spondylitis, Reiter's syndrome, and psoriatic arthritis. These disorders are characterized by typical deformities and instabilities of the cervical spine that result from the destruction caused by synovitis in bony and ligamentous structures in the neck. The treatment of these inflammatory lesions differs from the treatment of similar lesions found in the posttraumatic or degenerative spine. This article attempts to outline the epidemiology, clinical manifestations, and natural history of these conditions. Various radiographic parameters for evaluating disease progression have been used over the years, and their usefulness is reviewed in the context of recent studies better defining the radiographic natural history of these lesions. An algorithm for the use of the various imaging methods including magnetic resonance scanning is provided, and recent progress in delineating the proper timing of surgical intervention and the predictors of neurologic recovery is presented. The current surgical procedures available to treat these conditions are discussed with emphasis on distinguishing those cases in which stabilization alone is required from those in which a decompression procedure is also necessary.     

Biomechanics of injury of the cervical spine

Whiplash injuries of the cervical spine are of special medical and socio-economic importance. Biomechanical studies of the injury have proven, that a hypertranslation of the capito-cervical region takes place first, leading to ligamentous hyperdistension and ruptures, when exceeding elastic deformation, thus possibly resulting in mechanical disturbance and rotatory malpositioning. Diagnosis of so called "functional disorders" bears difficulties concerning objective tests for structural lesions. This demands the definition of diagnostic parameters and clinical signs, which also consider vegetative phenomena. This paper aims at a systematic clinical and radiological check. Adequate therapeutic means have to be concordant to prognosis. Therefore functional parameters should already determine differential diagnosis. This is based on technical feasibilities and needs future scientific efforts.     

Surgery in the degenerative cervical spine

Degenerative changes of the cervical spine include changes of the bony and discoligamentous structures that can create mechanical alterations of the anatomy. Compressive syndromes and deformation or instability represent basic indications for surgery. In the upper cervical spine, osteoarthritis of the C1-C2 facet manifests with suboccipital pain syndrome caused by generally unilateral degenerative changes of the atlantoaxial facet. Fixation and atlantoaxial fusion represent the treatment of choice. In rare instances the presence of os odontoideum is responsible for atlantoaxial instability. Narrowing of the lateral recess in the subaxial spine produces radicular symptoms. The clinical symptoms should be supported with imaging methods such as computed tomography or magnetic resonance imaging. Selective decompression produces satisfactory results. Spondylotic cervical myelopathy requires the addition of neurophysiologic investigations. Posterior decompression with laminoplasty or anterior decompression procedures with corpectomy of the involved segments represent therapeutic options with comparable results. In the presence of axial neck pain, the exact location of the painful segment challenges clinicians and radiologists. Only in cases in which the clinical findings correlate with the radiologic changes should surgical fusion be considered as a last therapeutic means to resolve the painful condition.     

Clinical outcomes after cervical spine fusion

The advent of sterile technique, modern anesthesia, and organized industrial society have allowed for great advances and widespread use of cervical arthrodesis for a variety of disorders. This article defines expected outcome for cervical arthrodesis used to treat degenerative disease, trauma, deformity, and a variety of other disorders.     

Medicolegal aspects of athletic cervical spine injury

Here we describe properties of the P2-purinoceptor, which is involved in the regulation of the key enzyme of estrogen biosynthesis, aromatase cytochrome P-450, in stromal cells from human adipose tissue. Aromatase activity induced by cortisol and platelet-derived growth factor BB (PDGF-BB) is further increased by addition of ATP, ADP, AMP and, albeit with reduced potency, adenosine, GTP and adenosine(5')tetraphospho(5') adenosine. Stable P1-purinoceptor agonists are inactive, whereas P2X-purinoceptor agonists mimic the effects of purine(s) (nucleotides). Prior incubation of cells with a P2-purinoceptor antagonist, but not P1-purinoceptor antagonists, blocks augmentation of aromatase activity by all ligands. Nucleotides, but not adenosine, retain their ability to augment aromatase activity in the presence of adenosine deaminase, indicating that they do not act via their metabolite adenosine. These results lead to the conclusion, that at least one member of the P2-subclass of purinoceptors exists in adipose tissue and is involved in modulation of aromatase activity in vitro. The pharmacological profile of the P2-site differs from those reported for cloned P2-purinoceptors, but is similar to that of the P2X-subclass. Therefore, a combined response of different members of the P2X-purinoceptor subclass or of members of different P2-purinoceptor subclasses cannot be discounted. Purinoceptor activation triggers cytoplasmic calcium transients, which, in contrast to aromatase induction, are independent from the presence of cortisol and PDGF-BB. Therefore the involved P2-purinoceptor(s) seem(s) to be constitutively expressed in human adipose tissue stromal cells. P2-purinoceptor(s) might provide a direct link between sympathetic nerve activity and estrogen biosynthesis in human adipose tissue. Furthermore it (or they) may contribute to the regulation of lipolysis.     

Reduction and positioning of cervical spine injuries

Prerequisites for successful reduction of cervical spine injuries are an exact analysis and classification of every lesion. In locked dislocations disc protrusion should be excluded prior to reduction by MRI or CT-scan. For manual reduction and closed manipulation by the trauma surgeon we use a halo-ring which is applied in local anaesthesia and fluoroscopic control. The anatomic position is maintained by a halo-fixator until surgery. Skeletal traction is used mainly for locked dislocations and late malalignements. Traction is provided by a halo-ring and weights up to 20 kg. Repeated clinical and neurological examinations are necessary to rule out overdistraction of the spine or neurologic deterioration. The weight may be reduced after reduction to 2 kg. For intraoperative positioning and reduction of cervical spine injuries we designed a special device which is connected to the halo ring and allows to fix the head and spine in any desired position. It may be used in prone or supine position of the patient. Operative reductions are rarely necessary on the cervical spine. Typical indication are fractures of posterior elements of the spine preventing closed reduction. Reduction manoeuvers depend on the kind of injury and are mainly composed of traction and a reversal of the trauma mechanism. The most severe complication is a neurologic deterioration. Reports in literature about 13 patients having sustained such a fate are showing the following: In most cases disc material dislocated in the spinal canal during reduction could be made responsible for the catastrophic course. Especially at risk are patients with open reduction from a posterior approach.     

Sodium nitroprusside and intracranial pressure

The effects of sodium nitroprusside on intracranial pressure were studied in 10 patients, candidates for surgical treatment, prior to anaesthesia. Blood pressure was lowered to at least 50% of its initial value. In all cases, at the beginning of nitroprusside infusion, both the mean and the pulse intracranial pressures increased (mean increase: 83.2% of the initial value). At a certain moment, however, while the blood pressure continued to fall, the mean intracranial pressure did not increase any more; on the contrary, it decreased. On the other hand, in many cases, the pulse intracranial pressure continued to increase. No neurological or EEG changes were observed. The possible changes of cerebral circulation and CSF dynamics underlying the phenomena observed are discussed.     

Reconstruction of cervical stability following old facet dislocation of cervical spine]

One hundred fifty adolescent inpatients with major depression were systematically assessed for demographic and clinical differences between psychotic and nonpsychotic depression. Delusions and/or hallucinations were present in 10% of the subjects. The psychotic group had significantly more frequent and severe suicidal ideation. Posttraumatic stress disorder was also more frequent in the psychotic group.