Cervical Spine Instability Research Articles

Repeated vertebrobasilar thromboembolism in a patient with severe upper cervical instability because of rheumatoid arthritis

Background context Although many reports have examined upper cervical rheumatoid arthritis (RA) and spinal cord disorders resulting from RA lesions, few cases of thromboembolic events in the vertebrobasilar system associated with RA lesions of the upper cervical spine have been reported. Purpose We encountered a rare case of repeated vertebrobasilar thromboembolism with severe upper cervical instability resulting from RA. Furthermore, we obtained clinical images of the vertebrobasilar system just before and after the first thromboembolic event. We thus present the case of a patient with RA who recovered without surgery from repeated vertebrobasilar thromboembolism that might have been caused by severe upper cervical instability. Study design Case report. Methods A 59-year-old man with a 14-year history of RA experienced nuchal pain because of severe atlantoaxial and vertical subluxations. While awaiting surgery, he developed left Wallenberg syndrome because of occlusion in the left vertebral artery (VA). Five days later, he displayed impaired consciousness and symptoms of right Wallenberg syndrome. Emergency magnetic resonance angiography showed occlusion in the basilar artery. After thrombolytic therapy, he gradually recovered. Results Because we presumed that the patient’s recurrent thrombus formation resulted from kinking of the right VA caused by severe instability of the upper cervical spine, we planned to treat him surgically despite his impaired consciousness and tracheostomy. However, the anesthesiologist would not approve surgery because the patient had high-risk conditions. The cervical spine was thus realigned and immobilized in a halo apparatus for 3 months to achieve stability. Now, more than 5 years after these events, the patient has experienced no more thromboembolic events and his condition has remained stable, without need for surgery. Conclusions Repeated vertebrobasilar thromboembolism in patients with RA may sometimes be caused by severe upper cervical instability that can be treated without surgery.

Retrospective audit of the air‐Q intubating laryngeal airway as a conduit for tracheal intubation in pediatric patients with a difficult airway

To assess the efficacy of the ILA as a conduit for tracheal intubation in pediatric patients with a difficult airway. The primary goals of this retrospective audit were to assess the clinical performance of the ILA in pediatric patients with a difficult airway, expand on our initial favorable experience with this device, and collect pilot data for future prospective and comparison studies. The charts of patients with a difficult airway in whom the ILA was used during a period of 1 year in a freestanding pediatric institution were reviewed following a practice change in the authors' institution favoring the ILA over the laryngeal mask airway as a conduit for tracheal intubation. Thirty-four pediatric patients had an ILA placed during the course of their airway management. Eight of the 34 patients in this cohort required emergent airway management. The median age was 47.1 (0.3-202.2) months and the median weight was 16.3 (3.9-86.0) kilograms. Three of the cases were unanticipated difficult airways and the remaining were anticipated difficult airways as a result of craniofacial syndromes (n = 21), cervical spine instability or immobility (n = 7), or airway hemorrhage (n = 3). Thirty-three of the 34 patients (97%) were intubated on the first attempt through the ILA, with the aid of a fiberoptic bronchoscope (n = 25), a Shikani Optical Stylet (n = 7), or blindly (n = 2). In one patient, blind tracheal intubation required a second attempt for successful intubation, making the overall success rate 100%. Oxygen desaturation was noted in 6 of the 34 cases. In a series of pediatric patients with difficult airways, the ILA was successfully used as a conduit for tracheal intubation in all patients. Visualization techniques may offer a greater degree of success in intubations through the ILA due to the potential for epiglottic down-folding in children.

A Review of Complications Associated With Craniocervical Fusion Surgery

Fusion at the craniovertebral junction is performed to treat instability of the upper cervical spine and occiput. The literature consists exclusively of case series in which complication rate and avoidance are variably addressed. To describe the rates of various complications encountered during craniocervical fusions and discuss preoperative and perioperative strategies useful for risk reduction. A computerized search of PubMed for literature on craniocervical fusion and other upper cervical fusions was performed. Keywords used in the search included: occipitocervical fusion, odontoid screw, atlantoaxial fusion, with and without complications, anterior fixation, lateral mass screw, transarticular screw, halo, vertebral artery injury, and odontoid fracture. References were limited to studies on human subjects. Other sources were identified from the reference lists of relevant publications. Twenty-two reports described data derived from 2274 procedures analyzed for complications. The most commonly encountered perioperative complications were related to instrumentation failure after nonunion with rates as high as 7% during occipitocervical fusion and 6.7% during atlantoaxial fusion. Other commonly encountered complications included injury to the vertebral artery (1.3%-4.1% during placement of C1-C2 transarticular screws, most commonly in the case of high-riding vertebral artery), dural tears, and wound infection. Occipitocervical or atlantoaxial fusion procedures can be performed with low morbidity. Safety is enhanced with appropriate preoperative assessment of anatomic variants and preparation for perioperative management of complications.

Diagnosis of Unstable Cervical Spine Injuries: Laboratory Support for the Use of Axial Traction to Diagnose Cervical Spine Instability

The ability to detect damage to the intervertebral structures is critical in the management of patients after blunt trauma. A practical and inexpensive method to identify severe structural damage not clearly seen on computed tomography would be of benefit. The objective of this study was to assess whether ligamentous injury in the subaxial cervical spine can be reliably detected by analysis of lateral radiographs taken with and without axial traction. Twelve fresh, whole, postrigor-mortis cadavers were used for this study. Lateral cervical spine radiographs were obtained during the application of 0 N, 89 N, and 178 N of axial traction applied to the head. Progressive incremental sectioning of posterior structures was then performed at C4-C5 with traction imaging repeated after each intervention. Intervertebral distraction was analyzed using computer-assisted software. Almost imperceptible intervertebral separation was found when traction was applied to intact spines. In the subaxial cervical spine, the average posterior disc height consistently increased under traction in severely injured spines. The average disc height increase was 14% of the C4 upper endplate width, compared with an average of 2% in the noninjured spines. A change of more than 5% in posterior disc height under traction was above the 95% confidence interval for intact spines, with sensitivity of 83% and specificity of 80%. Applied force of 89 N (20 lb) was sufficient to demonstrate injury. The combination of assessing alignment and distraction under traction increased both the sensitivity and specificity to nearly 100%. This study supports further clinical investigations to determine whether low-level axial traction may be a useful adjunct for detecting unstable subaxial cervical spine injuries in an acute setting.

Application of (lamellar) keratoplasty and limbal stem cell transplantation for corneal clouding in the mucopolysaccharidoses – a review

AbstractCorneal clouding or opacification is a prominent feature of mucopolysaccharidosis (MPS), particularly in MPS I and VI. In patients with marked corneal clouding and visual impairment, penetrating keratoplasty may be considered to improve the patient's vision, functional capacity and quality of life. In MPS, glycosaminoglycans mainly accumulate in the corneal stroma and not in Descemet's membrane or the endothelium, therefore deep anterior lamellar keratoplasty (DALK) may be preferred in these patients over penetrating keratoplasty. Although there are only limited data on the use of DALK in MPS (I and VI) patients, the results are generally favourable. Nonetheless, when deciding on whether to perform keratoplasty in patients with MPS, the risk of general anaesthesia due to potential concomitant cardio‐pulmonary problems and cervical spine instability, the potential presence of other ocular manifestations that also impair vision (e.g. glaucoma, retinal degeneration and optic atrophy) and/or complications such as allograft rejection and the risk of re‐opacification of the graft, all need to be taken into consideration. Limbal stem cell transplantation, which can be combined with keratoplasty, also holds potential promise in the treatment of these complex cases. A review of the indications, local and systemic risks, techniques of lamellar and penetrating keratoplasty, and the potential of limbal stem cell transplantation is provided in the context of corneal opacity in MPS.

Orotracheal Intubation

The advantages of endotracheal intubations are many: patency of airway is reasonably assured, secretions may be removed easily from the tracheobronchial tree, the airway is better protected against aspiration, ventilation can be regulated, and drugs can be administered. The procedure is the "gold standard" of airway control, and the oral route is the most common used. The patient is assessed for potential difficulties that may arise from abnormalities of face and mouth: large face, large tongue, hypoplastic mandible, prominent or diseased maxillary teeth or facial fractures; or abnormalities of the neck: potential or real cervical spine instability, swelling, or laryngeal trauma. A plan is devised, together with one or more alternatives, should unforeseen difficulties arise, and in adherence to the principle of never removing the compensations of a coping patient. The skill is learned and practiced so that a gentle facility is always present at times of greatest need.

Predictors of aggravation of cervical spine instability in rheumatoid arthritis patients: the large joint index

BackgroundImproved rheumatic drugs have provided significant benefits, but activities of daily living are not improved if spinal symptoms are overlooked. Furthermore, the appropriate timing for examining the cervical spine during follow-up is unclear. MethodsTo evaluate the relations of cervical spine instabilities and an index for cervical spine lesion in rheumatoid arthritis (RA) based on extremity radiographs, we examined preoperative radiographs of 100 RA patients who underwent total knee arthroplasty. Radiographic results for eight large joints (bilateral shoulders, elbows, hips, and knees) were graded as follows: Larsen grade ≥2 for each joint was scored as 1 point, which we refer to as the “large joint index” (LJI), based on 0–8 points. The associations of radiographic cervical lesions with LJI, Ranawat class, the disease duration, RA drugs, or blood analysis data were evaluated. ResultsAtlantoaxial subluxation (AAS) (≥5mm) was found in 45 patients, vertical subluxation (VS) (≤13 mm) in 42, a posterior atlantodental interval (PADI) (<14mm) in 21, and subaxial subluxation (SAS) (≥3 mm) in 23. Most patients with a PADI < 14mm (19/21, 90%) were complicated with both AAS and VS. LJI had a significant association with AAS (P < 0.0001), VS (P < 0.01), and PADI (P < 0.01). The PADI was significantly lower (P < 0.0001) and the LJI was significantly higher (P < 0.01) in patients of Ranawat class II compared to patients of Ranawat class I. The disease duration, age at surgery, and age at onset were also significantly associated with cervical instabilities. ConclusionsPADI should be recognized as a predictor of paralysis with anteroposterior instability and vertical and middle-low cervical spine instability. The LJI proposed in this study has the possibility of being a predictor of cervical lesions. Patients with RA onset at a young age and a long disease duration also have a risk of progression of cervical spine instability.

Clinical application of C2 laminar screw technique

C2 laminar screws have become an increasingly used alternative method to C2 pedicle screw fixation. However, the outcome of this technique has not been thoroughly investigated. A total of 35 cases with upper cervical spinal instability undergoing C2 laminar screw fixation were reviewed. All cases had symptoms of atlantoaxial instability, such as craniocervical junction pain, and were fixed with the Vertex cervical internal fixation system. A total of 68 screws were placed and hybrid constructs (a C2 translaminar screw combined with a C2 pars screw) were incorporated in two patients. In this series, there were no intraoperative complications and no cases of neurological worsening or vascular injury from hardware placement. Computed tomographic scans demonstrated a partial dorsal laminar breach in ten patients. None of these resulted in neurological symptoms. None of the patients was found to have a breach of the ventral laminar cortex. All the C2 laminar screws fixations were performed successfully. There was no instability seen on the films with no evidence of hardware failure or screw loosening during the follow-up period in all patients. In conclusion, C2 laminar screw technique is straightforward and easily adopted; it can efficiently and reliably restore upper cervical stability. It is an alternative method to C2 pedicle screw fixation, especially in patients with unilateral occlusion of vertebral artery and pedicle deformity of C2.

Brain Stem Compression and Atlantoaxial Instability Secondary to Chronic Rheumatoid Arthritis in a 67-Year-Old Female

Objective This case study describes a patient with long-standing rheumatoid arthritis of the cervical spine who presented with significant bone destruction, gross joint derangement, and a potentially life-threatening complication, basilar invagination with brain stem compression. The pathophysiology, clinical presentation, imaging, and surgical management are discussed. Clinical Features A 67-year-old female presented to a chiropractic clinic with chronic neck pain of 30 years of duration complicated by rheumatoid arthritis. Her neck pain had recently exacerbated and was radiating into her trapezius muscle and shoulders. She also reported a recent onset of mild dysphagia. The patient was referred to a neurosurgeon for consultation and management. Intervention and Outcome Computed tomography and magnetic resonance imaging of the cervical spine demonstrated significant bone destruction, gross joint derangement, and basilar invagination. There was moderate stenosis of the foramen magnum secondary to basilar invagination with significant brain stem compression. The patient underwent surgical stabilization fusion from the occiput to T2 using a posterior approach. Her pain severity was lessened after surgery, and the dysphagia had not progressed suggesting stabilization of brain stem compression. Conclusion Patients with long-standing rheumatoid arthritis of the cervical spine often present with chronic neck pain. Cervical spine instability may arise from rheumatoid osteolysis and is also secondary to horizontal or vertical subluxation of the atlantoaxial and occipitoatlantal regions, respectively. High-velocity, low-amplitude manipulation of the upper cervical spine is an absolute contraindication in cases of atlantoaxial instability. A timely diagnosis and favorable surgical outcome provided relief from a potentially life-threatening disorder. This case exemplifies the clinical caution necessary for managing patients with chronic cervical spine pain complicated by rheumatoid arthritis.

Mucopolysaccharidosis VI

Mucopolysaccharidosis VI (MPS VI) is a lysosomal storage disease with progressive multisystem involvement, associated with a deficiency of arylsulfatase B leading to the accumulation of dermatan sulfate. Birth prevalence is between 1 in 43,261 and 1 in 1,505,160 live births. The disorder shows a wide spectrum of symptoms from slowly to rapidly progressing forms. The characteristic skeletal dysplasia includes short stature, dysostosis multiplex and degenerative joint disease. Rapidly progressing forms may have onset from birth, elevated urinary glycosaminoglycans (generally >100 μg/mg creatinine), severe dysostosis multiplex, short stature, and death before the 2nd or 3rd decades. A more slowly progressing form has been described as having later onset, mildly elevated glycosaminoglycans (generally <100 μg/mg creatinine), mild dysostosis multiplex, with death in the 4th or 5th decades. Other clinical findings may include cardiac valve disease, reduced pulmonary function, hepatosplenomegaly, sinusitis, otitis media, hearing loss, sleep apnea, corneal clouding, carpal tunnel disease, and inguinal or umbilical hernia. Although intellectual deficit is generally absent in MPS VI, central nervous system findings may include cervical cord compression caused by cervical spinal instability, meningeal thickening and/or bony stenosis, communicating hydrocephalus, optic nerve atrophy and blindness. The disorder is transmitted in an autosomal recessive manner and is caused by mutations in the ARSB gene, located in chromosome 5 (5q13-5q14). Over 130 ARSB mutations have been reported, causing absent or reduced arylsulfatase B (N-acetylgalactosamine 4-sulfatase) activity and interrupted dermatan sulfate and chondroitin sulfate degradation. Diagnosis generally requires evidence of clinical phenotype, arylsulfatase B enzyme activity <10% of the lower limit of normal in cultured fibroblasts or isolated leukocytes, and demonstration of a normal activity of a different sulfatase enzyme (to exclude multiple sulfatase deficiency). The finding of elevated urinary dermatan sulfate with the absence of heparan sulfate is supportive. In addition to multiple sulfatase deficiency, the differential diagnosis should also include other forms of MPS (MPS I, II IVA, VII), sialidosis and mucolipidosis. Before enzyme replacement therapy (ERT) with galsulfase (Naglazyme®), clinical management was limited to supportive care and hematopoietic stem cell transplantation. Galsulfase is now widely available and is a specific therapy providing improved endurance with an acceptable safety profile. Prognosis is variable depending on the age of onset, rate of disease progression, age at initiation of ERT and on the quality of the medical care provided.

Reference data for assessing widening between spinous processes in the cervical spine and the responsiveness of these measures to detecting abnormalities

Background context Traumatic injury to the spine is evaluated and treated based on the perceived stability of the spine. Recent classification schemes have established the importance of evaluating the discoligamentous complex to fully comprehend stability. There are a variety of techniques to evaluate the discoligamentous complex, including assessment of interspinous distance. However, there currently are no clinically validated methods to define and assess abnormal interspinous widening. Purpose The purpose of the study was to provide reference data and evidence to support the objective use of spinous process widening in the diagnosis of cervical spine injury and instability. Study design The study was designed to be biomechanical and observational. Methods Distances between spinous processes were measured from lateral flexion-extension X-rays of 156 skeletally mature asymptomatic subjects who reported never having had neck symptoms as well as 12 whole human cadavers before and after creating increasingly severe damage to posterior structures. Cervical interspinous distances were measured and then normalized to the width of the C4 vertebral end plate. The change in the distance from flexion to extension was also calculated. Results Descriptive statistics, including the 95% confidence intervals for each cervical level were tabulated for 863 levels in 149 analyzable asymptomatic volunteers. In the simulated cadaver model, interspinous widening was highly specific and mildly sensitive for detecting damage to the posterior structures of the cervical spine. Conclusions This study provides reference data that can be used to quantitatively assess interspinous process widening in the cervical spine. Application of the reference data to a cadaver model of cervical trauma suggests that although objective evidence of abnormal widening may be uncommon, when present, it is suggestive of extensive damage to the cervical spine. Derived from this data were two “rule of thumb” criteria to identify abnormal interspinous widening in flexion X-rays; when greater than 30% relative to an adjacent level (40% between C1–C2 and C2–C3) or greater than 50% of the anterior-posterior width of the C4 vertebral body (30% for C2–C3).

Klippel-Feil syndrome: a case report

To report the clinical presentation and peculiarity of management of Klippel-Feil syndrome (KFS) at the University of Abuja Teaching Hospital, Gwagwalada. KFS is a rare pathology that has not been previously reported on in Nigeria. Case review was employed to report this pathology. This case is a 10 year old boy with KFS presenting with cosmetic blemish and scoliosis. Surgical treatment of the cosmesis was offered but patient defaulted because of fund due to their low income. KFS is an uncommon pathology in the male. The management is essentially conservative but surgery is an option if there was cervical spine instability, scoliosis and cosmetic blemish.

Atlantoaxial Transpedicular Screw Fixation for the Management of Traumatic Upper Cervical Spine Instability

Objective: The morbidity and mortality are high for traumatic upper cervical spine instability with cervico-medullary compression. In a clinical retrospective study, the clinical and radiographic results of occipitocervical (OC) fusion using posterior atlantoaxial transpedicular screw fixation in 12 patients with traumatic upper cervical spine instability was reviewed. Methods: Twelve patients with traumatic upper cervical spine instability (8 males and 4 females) were treated at our department over four years. Instability resulted from acute C1-C2 dislocation (4 cases), an acute unstable C2 fracture (1 case), acute C1-2-3 fracture dislocation (2 cases), acute C1 fracture (1 case), OC dislocation (2 cases) and old unstable C2 fracture (1 case). All 12 patients were internally fixed with occipital-/C1-C2 transpedicular screw fixation. The outcome (mean follow-up period, 16.5 months) was based on clinical and radiographic review using the Japanese Orthopedic Association (JOA) score. Results: Four neurologically intact patients remained the same after surgery. Among eight patients with cervical myelopathy, clinical improvement was noted in six cases (75%). The JOA score of the 8 patients were 9.4 (range, 0-16) before surgery and 12.1 (range, 0-17) with a recovery rate of 38.3% at the time of the last follow up. One patient died 2 months after the surgery because of pneumonia and sepsis. Fusion was achieved in 10 patients (90.9%) by the last follow-up. Conclusion: Early OC fusion is recommended in cases with traumatic upper cervical spinal instability, OC fusion with posterior atlantoaxial transpedicular screw fixation was a safe and effective method for the treatment of traumatic cervical spine instability. (J Kor Neurotraumatol Soc 2010;6:143-149)

C5 Palsy After Cervical Decompression Procedures

Study Design Review of literature. Objectives To review the literature regarding the clinical features, incidence, underlying mechanism, possible prevention, and prognosis of C5 palsy after cervical decompression surgery. Summary of Background Data Palsy of the C5 nerve after cervical spine decompression surgery is a well-known complication. There is persistent controversy concerning the underlying mechanism and appropriate prophylaxis. Methods A review of studies describing C5 palsy after cervical spine decompression procedures was carried out. Results Postoperative C5 palsy can be present after cervical spine decompression with a reported incidence between 0% and 50%. Postoperative C5 palsy has been reported regardless of the underlying cause of cervical spinal cord compression and the surgical procedure carried out. The current literature describes 5 basic underlying mechanisms. These include direct injury to the nerve root, segmental spinal cord pathology, progressive cervical spine malalignment and instability, nerve root traction, and abnormal spinal cord blood flow and reperfusion injury. The true pathomechanism of postoperative C5 palsy remains unclear and no single method of prevention is regularly used. The prognosis of postoperative C5 palsy is generally good with full recovery reported in the majority of patients. Conclusions Postoperative C5 palsy is a complication seen after surgical decompression of the cervical spine. It can occur regardless of the cause of cervical spinal cord compression and the surgical procedure carried out. Numerous theories exist as to the underlying cause of postoperative C5 palsy, but there is no strong evidence to support any single pathomechanism or appropriate prophylaxis. Most patients with postoperative C5 palsy experience full recovery within 6 months, although many patients continue to have some residual pain or neurologic deficit.

2009 in Review

2009 in Review

Balancing the Force of Direct Laryngoscopy with Manual In-Line Stabilization

Manual in-line stabilization (MILS) is employed during direct laryngoscopy in patients with known or potential cervical spine instability to try to stabilize the spine. A recent article by Santoni et al. evaluated how MILS affected the pressure against the tongue and jaw during direct laryngoscopy.1Pressure was measured with sensors attached to the upper surface of a Macintosh 3 blade. In nine anesthetized paralyzed patients, institution of MILS increased the pressures during laryngoscopy almost two-fold, as compared with pressures measured without MILS. Although MILS is intended to stabilize the cervical spine during laryngoscopy, the authors proposed that “secondary increases in pressure application with MILS have the potential to increase pathologic cranio-cervical motion.”In the absence of MILS, upward and forward force exerted on the airway will be transmitted in some part to the cervical spine and the spine will move, as Dr. Todd and his group have demonstrated.2The force will also compress the tongue, contributing to exposure of the vocal cords with laryngoscopy.3However, it is not clear how much movement-generating force, if any, will be applied to the spine if MILS is instituted as described. Santoni et al. explain that MILS is performed by an assistant holding the patient's occiput and applying “forces equal and opposite to those created by the anesthesiologist.”1One might expect that matching laryngoscopy force with an equal and opposite force would result in no net force on the head, thus reducing the force and movement of the cervical spine, as compared with the situation with no MILS. In fact, Santoni et al. list the goal of the MILS as preventing or minimizing head and neck movement.How MILS actually works in practice is another issue. The assistant performing the task is guided by feel without any measurement of force. Thus, MILS may not balance the force of laryngoscopy and may not minimize movement. The Santoni group may be correct that MILS does not accomplish the objective. However, they only measured the pressure on the laryngoscope and did not evaluate the force exerted by MILS . Thus, they do not know what the net force was and cannot say one way or another from this body of research whether MILS had the potential to reduce or increase the craniocervical motion.The observation that MILS worsened glottic visualization, a finding also reported by other investigators, is interesting and could be an outcome of the way the MILS was executed. The increased force on the tongue with MILS should lead to greater compression of the tongue, increase the space in the airway and, if anything, improve the glottic view rather than impairing it. In a study examining simulated cervical spine precautions, we showed several years ago that having an assistant hold a patient's head firmly against the table during laryngoscopy significantly reduced the amount of head extension necessary to expose the vocal cords compared to the state with no head stabilization.4We suggested that less head extension was needed because the downward pressure on the head allowed the laryngoscopist to lift more forcibly and achieve greater displacement of the tongue from the field of view. Some additional factor must be operative in the Santoni study to worsen the view with MILS. Perhaps the main effort of the assistants was to resist head extension, rather than balance the upward force of laryngoscopy. Limited head extension would make laryngoscopy more difficult and could contribute to higher grade views. In our 1991 paper, the assistants did not oppose head extension.We congratulate Santoni et al. on their highly relevant study. The degree to which MILS is beneficial in patients with potential cervical spine injury is an important and timely issue.5The application of physics and engineering principles to medical problems will help answer clinical questions such as this. We would welcome further research about how laryngoscopy and MILS impact the forces exerted on the spine and airway, and how best to implement MILS.*VA San Diego Healthcare System and University of California, San Diego, California. rhhastings@ucsd.edu

Tracheal intubation with the AirwayScope™ videolaryngoscope using straight vs curved reinforced tubes

To the Editor, The AirwayScope (AWS-S100; IMI Co., LTD., Koshigaya Saitama, Japan) is proposed as an alternative to the classical Macintosh laryngoscope for tracheal intubation in patients with cervical spine instability and/or neck stiffness, because it offers a better laryngeal view with less cervical spine movement. Its introducer, the INTLOCK, gives the straight reinforced tube a downward orientation, whereas the curved tube points upwards. Therefore, intubation difficulties may be more frequent with the straight tube because of more likely impingement with the arytenoids (Fig. 1). We compared straight and curved reinforced endotracheal tubes in terms of intubation success rate, delay of intubation, incidence of impingement with the arytenoids, and postoperative sore throat and hoarseness. After obtaining approval from the Research Ethics Committee of Wakayama Medical University and written informed patient consent, 55 patients (45–84 yr) American Society of Anesthesiologists’ physical status I–III undergoing lumbar spine surgery had their tracheal intubation performed with an AWS using a tube size 7.5 for females (F) and 8.0 for males (M). Patients were assigned to the curved group (curved reinforced tube; Covidien, Mansfield, MA, USA), n = 25, M/F = 14/11, or to the straight group (straight reinforced tube; Fuji Systems Co., Bunkyo-ku, Tokyo, Japan), n = 30, M/F = 14/16. If intubation did not succeed at the first attempt, another insertion was allowed by adjusting the AWS direction upward. Twenty-four hours after surgery, severity of sore throat and hoarseness were graded. Sample size calculation was performed using the time from laryngeal view to intubation as the primary end point. Twenty-five patients were needed for an 89% power to detect changes of 4.8 sec at a significance level of 0.05; standard deviation (SD) = 5.2. Statistical analysis was performed using the Mann–Whitney U test or the v test. Patients in both groups had similar characteristics, including sex ratio, age, body mass index, Mallampati score, and duration of anesthesia. The intubation success rate was greater in the curved group than in the straight group (100% vs 83.3%, respectively; P 0.05). When failure of tracheal intubation occurred in the straight group, it was due to the arytenoid cartilages interfering with the tube advancement and not due to an inadequate view of the larynx. The time from laryngeal view to intubation lasted longer in the straight group than in the curved group (11.1 ± 5.2 sec vs 6.3 ± 4.7 sec, respectively; mean ± SD; P 0.05), whereas the time until the glottic view did not differ between groups (10.2 ± 7.0 sec vs 9.8 ± 5.9 sec, respectively). These results suggest that intubation delay in the straight group was not due to the inadequate laryngeal view. The number of insertion attempts was greater in the straight group than in the curved group (2.4 ± 1.4 attempts vs 1.2 ± 0.5 attempts, respectively; P 0.05), reflecting the need for more upward adjustments of the introducer tip T. Minonishi, MD H. Kinoshita, MD, PhD (&) K. Tange, MD Y. Hatano, MD, PhD Wakayama Medical University, Wakayama, Japan e-mail: hkinoshi@nike.eonet.ne.jp; hkinoshi@wakayama-med.ac.jp

Difficult intubation during rapid sequence induction in a parturient with Ehlers-Danlos syndrome, hypermobility type

There have been several reports of resistance to local anaesthetic agents in women with Ehlers-Danlos syndrome, hypermobility type, also known as Ehlers-Danlos syndrome Type III. General anaesthesia with rapid sequence induction was performed for caesarean section due to prolonged second stage of labour, but intubation proved to be difficult. We propose that intubation difficulty probably arose from collapse of fibro-elastic tissues and adjoining C-shaped cartilages of the trachea with appropriately applied cricoid pressure. We found no other case reports of difficult intubation in patients with Ehlers-Danlos syndrome, hypermobility type. There are reports of cervical spine instability and temporomandibular joint dysfunction in patients with this syndrome suggesting a potential for difficult airway management. Additional anaesthetic problems associated with Ehlers-Danlos syndrome involve patient positioning and vascular access.

Unstable Subaxial Cervical Spine Injury With Normal Computed Tomography and Magnetic Resonance Initial Imaging Studies

Case series. To describe 4 cases of unstable subaxial cervical spine injury not demonstrated with initial radiograph, computed tomography (CT), and magnetic resonance (MR) imaging. When evaluating the cervical spine for ligamentous or osseous injuries in the blunt trauma patient population, negative predictive value measurements of 100% for CT and MR imaging have been published. Unstable subaxial cervical spine injury has rarely been reported in the spine literature in conjunction with initial radiograph, CT, and MR imaging demonstrating no osseous or ligamentous injury. Historically, reports of subacute cervical spine instability following trauma exist and were presented before the availability of MR and multidetector CT imaging. We report 4 examples of unstable subaxial cervical spine injury each with initial imaging interpreted as negative. All 4 cases presented at a level-one tertiary care facility. Follow-up radiographs demonstrated unstable cervical spine injuries requiring surgical stabilization. Notwithstanding high sensitivities, specificities, and negative predictive values for cervical spine imaging and "clearance" mechanisms, 4 cases that illustrate the potential for undetected unstable cervical spine injuries are presented. Tremendous advancements in medical imaging have been made. However, radiograph, CT, and MR imaging may still fail to accurately translate the anatomic and dynamic complexity of the cervical spine into digital images that accurately guide clinical practice. A full understanding of and keen appreciation for the fact that no imaging technique, classification method, or clearance protocol can produce 100% sensitivity at all times is essential. These case reports cumulatively demonstrate a 0.04% to 0.2% incidence of undetected cervical injury requiring surgical stabilization. Removing cervical collar immobilization as quickly as possible based on negative interpretation of imaging data may prove harmful in a measurable percentage of patients and must be undertaken with caution only after clinical correlation and strict follow-up is established.

Endotracheal tube as a nasogastric tube introducer

To the Editor, Nasogastric tube (NGT) insertion is a procedure performed routinely in critical care settings. However, NGT placement often proves to be a daunting task, especially in the setting of anesthetized/uncooperative patients with anatomic distortion (i.e., patients with cervical spine instability and/or restricted neck movement) and an endotracheal tube (ETT) already in situ for airway protection and support of the respiratory system. In fact, serious complications secondary to NGT placement appear often in the literature. Therefore, NGT insertion may be a complex procedure that requires skill, experience, and the ability to improvise if it does not proceed smoothly. A 63-year-old male patient, who was sedated and mechanically ventilated in our intensive care unit, had a hard cervical collar in place after sustaining severe traumatic brain injury, cervical spine fracture, and multiple long bone fractures in a motor vehicle accident. The NGT was unintentionally removed during routine patient care, and despite many gentle and prolonged attempts, the on-call physicians’ efforts to re-insert the NGT were unsuccessful. The presence of the cervical collar created poor laryngoscopic views, even with the left molar approach, and the patient’s cervical spine injury did not allow maneuvres that could facilitate NGT insertion, such as neck flexion, turning the head laterally, lateral neck pressure, and forward displacement of the larynx. To this end, a number of techniques to advance the NGT were attempted without success, including blind insertion plus a combination of direct laryngoscopy and use of Magill forceps, placement of fingers in the posterior pharynx to guide the NGT tip downward, deflation of the ETT cuff, and use of a frozen NGT. Finally, a 9.5-mm internal diameter ETT (‘‘conduit’’ ETT) was placed in the oropharynx and—under direct laryngoscopy—was continually kept in contact with the posterior pharyngeal wall and behind the ETT already in place while simultaneously being advanced gently and as far as possible into the esophagus. A well-lubricated 14-Fr NGT was threaded into the ‘‘conduit’’ ETT and was advanced into the full length of the stomach without difficulty during the first attempt. Afterward, the ‘‘conduit’’ ETT was withdrawn and the NGT was pulled back, positioned at the appropriate length, and fastened in the usual way. It is worth noting that no change of head or neck position, no ETT cuff deflation, and no involvement of an assistant were necessary during this alternative mode of NGT insertion. The only technical requirement was to ensure that the ‘‘conduit’’ ETT diameter could accommodate the NGT, including its funnel-shaped proximal end. We did not determine fibreoptically the point where the NGT met resistance and was successfully bypassed by the ‘‘conduit’’ ETT. However, it has been previously shown that the most common sites of resistance at the laryngeal level are the piriform sinuses and the arytenoid cartilages. In conclusion, the use of an ETT as an introducer can facilitate NGT insertion in difficult settings. This alternative mode of NGT insertion is easy, inexpensive, and widely available in the operating room and the intensive care unit. In our view, it is worth considering this blind approach before the physician resorts to other techniques (i.e., videolaryngoscopy) that are either more expensive or that necessitate the involvement of additional equipment. P. Kopterides, MD (&) C. Papageorgiou, MD G. Dimopoulos, MD A. Armaganidis, MD 2nd Critical Care Department, ‘‘Attiko’’ University Hospital, 1 Rimini Str., Haidari, Athens, Greece e-mail: petkop@ath.forthnet.gr