Fatal cardiac tamponade associated with posterior spinal instrumentation. A case report

STUDY DESIGN: Case report of a fatal complication of pedicle screw instrumentation and review of the literature. OBJECTIVE: To describe the clinical and postmortem findings in a 35-year-old man who sustained a T11 burst fracture that was managed by transpedicular posterior instrumentation and who died 12 days after surgery of cardiac tamponade caused by a prick injury of the right coronary artery. SUMMARY OF BACKGROUND DATA: Posterior pedicle screw instrumentation is considered a safe and effective method for stabilizing a spinal motion segment. Nevertheless, there are several rare but significant complications that may occur. This is the first report of a heart tamponade after transpedicular screw insertion. METHODS: A 35-year-old man was treated for a T11 burst fracture with posterior transpedicular stabilization. The surgery was uncomplicated. RESULTS: Twelve days after the intervention, the patient died of cardiogenic shock. Postmortem examination showed a heart tamponade of 350 mL blood originating in a prick injury of the right coronary artery. Histologic findings showed evidence that the injury was caused during surgery by a Kirschner wire. CONCLUSION: There are numerous possible intraoperative complications in posterior pedicle screw fixation, such as nerve root and spinal cord injuries. This case of a fatal heart tamponade after transpedicular screw insertion is rare. It shows that the surgeon must be aware of potential risks associated with such a procedure and have a comprehensive three-dimensional understanding of the anatomic structures involved.     

Internal fixation of the spine in traumatic and scoliotic cases. The potential of pedicle screws

Internal fixation techniques are in common used to stabilize vertebral fractures and correct severe scoliosis. Consolidation of injured vertebrae with neighbouring intact vertebra is the goal in the former case whilst fusion of the vertebrae in a corrected position is aimed at in the latter case. Degenerative spine diseases are not considered in this paper. Classical instrumentation consists of rods (e.g., Cotrel-Dubousset, Harrington, Luque-Galveston) attached to the bone by means of hooks or wires. More recently, transpedicular screws are introduced as an alternative bone/implant interface. Comparing the results of several studies, the posterior pedicle screw based devices demonstrate the ability to produce the most rigid constructs. However, the insertion of pedicle screws implicates a relatively high complication risk and its success strongly depends on the experience of the surgeon. Incorrect drilled holes or malplacement of the screws can result in nerve root injuries and fracture of the pedicle. Studies reported complication ratios up to 30% with substantial neurological implications. A certain degree of automation of the critical actions may be necessary to enhance the safety of pedicle screw insertion. Two techniques of computer assisted spine surgery are compared. Both techniques permit a computer assisted surgical planning based on CT images. During operation the first system permanently observes the position of the drill relative to the spine and informs the surgeon on the deviation of the actual drill path to the planned drill path. The second system uses a pre-operative surgical planning to design and construct a mechanical drill guide, fitting perfectly on the patient's spine.     

Anatomic relations of the thoracic pedicle to the adjacent neural structures

STUDY DESIGN: This study analyzed anatomic parameters between the thoracic pedicles and the spinal nerve roots. OBJECTIVES: To quantitatively determine the anatomic relations of the thoracic pedicle to the adjacent neural structures. SUMMARY OF BACKGROUND DATA: Pedicular screw placement carries with it potential hazard to the surrounding neural structures, especially in the thoracic spine. No studies exist regarding the anatomic relations of the thoracic pedicle to the adjacent nerve roots. METHODS: Fifteen cadavers were obtained for study of the thoracic spine. All soft tissue was dissected off the thoracic spine. Laminectomy and total removal of the superior and inferior articular facets was then performed on C7-T1 through T12-L1 to expose the pedicles, nerve roots, and dura. Measurements were taken from the pedicle to the nerve root superiorly and inferiorly as well as between the pedicles. Also, the superoinferior diameter of the nerve root and the frontal angle of the nerve root were measured. Symmetrical structures were measured bilaterally. RESULTS: The results showed that no epidural space could be found between the dural sac and the pedicle in all 15 cadavers. The average distances from the thoracic pedicle to the adjacent nerve roots superiorly or inferiorly at all levels ranged from 1.9 to 3.9 mm and from 1.7 to 2.8 mm, with a minimum of 1.3 mm, respectively. The interpedicular distance increased from T1 (13.8 mm) to T3, slightly decreased in T4-T5, then gradually increased to T12 (16.6 mm). The superoinferior diameter of the nerve root increased consistently from 2.9 mm at T1 to 4.6 mm at T11. The frontal nerve root angle decreased consistently from T1 (120.1 degrees) to T12 (57.1 degrees), except at T4-T5. CONCLUSIONS: This study suggested that more care be taken into consideration in placing a transpedicular screw in the transverse plane than in placing a screw in the sagittal plane in the thoracic spine.     

Electrophysiologic analysis of the lumbosacral radiculopathy using nerve root conduction velocity (NRCV) and cauda equina action potentials (CEAP)

Nerve root conduction velocity (NRCV) and cauda equina action potential (CEAP) have been measured to assess the severity of lumbosacral radiculopathy, the level-specific diagnosis of the symptomatic roots, and to predict the outcome. This study included 71 patients (40 males, 31 females, average age of 54 years at the time of surgery) who underwent decompressive surgery for lumbar radiculopathy. The NRCV and CEAP were directly measured during the operation. The NRCV decreased significantly with progression of radicular symptoms. The NRCV showed a marked reduction in the nerve roots of the patients with a two years or longer history of radicular symptoms; or those with compression of the nerve roots on the imaging examinations; or nerve roots that were considered to have been subjected to persistent compression over a prolonged period with severe inflammation and adhesions. Multivariative analyses suggested that the NRCV correlated closely to the postoperative neurologic recovery, and the outcome of the lumbosacral radiculopathy could be predicted to some extent by measurements of NRCV. The level-specific diagnosis of the radiculopathy could be determined when the CEAP showed a more than 30% left-right potentials difference.     

Assessment of flail mitral leaflets by dynamic three-dimensional echocardiographic imaging

Patients with diabetic amyotrophy may have an inflammatory vasculopathy and may obtain reversal of neurological deficits with immunosuppression. We present a patient with NIDDM, subacute onset of painful asymmetric polyradiculopathy, and unilateral enhancement of lumbar nerve roots on MRI. Clinical improvement and resolution of nerve root enhancement occurred with immunosuppression. We suggest, therefore, that nerve biopsy and gadolinum-enhanced lumbosacral MRI be performed in all patients presenting with diabetic amyotrophy. If nerve root enhancement is present or if nerve biopsy shows perivascular infiltrates, we recommend a trial of immunosuppression.     

Microsurgical lumbosacral ganglionectomy, anatomic rationale, and surgical results

Recent anatomic and physiologic work suggests that there may be substantial numbers of unmyelinated sensory axons in the ventral roots. The cell bodies of origin for these unmyelinated axons would presumably be located in the dorsal ganglion. We have performed 18 microsurgical lumbosacral ganglionectomies over the past two years for chronic lumbosacral pain syndromes. In spite of preoperative nerve block trials, good results were obtained in only 10 of 18 patients. Four patients obtained some pain relief, and four patients no pain relief whatsoever. Microganglionectomy in the lumbosacral area is probably easier technically than the more traditional intradural rhizotomy, but may not yield any better results.     

The function of sensory nerve fibers in lumbar radiculopathy. Use of quantitative sensory testing in the exploration of different populations of nerve fibers and dermatomes

STUDY DESIGN: The function of sensory nerve fibers in patients with lumbar radiculopathy and in control individuals was evaluated using quantitative sensory testing. OBJECTIVES: To investigate the effect of lumbar nerve root compression on different populations of nerve fibers and to explore the function of sensory nerve fibers in neighboring nerve roots not involved in the mechanical compression. BACKGROUND DATA: Results from experimental and clinical studies indicate that chronic compression of lumbar nerve roots affects the large myelinated nerve fibers. The majority of nerve fibers involved in the sensation of pain, however, are small afferent nerve fibers. It is therefore of interest to study the effect of compression on large and small sensory afferent channels. Several authors have elucidated the biochemical interaction between disc tissue and nerve roots. Chemical substances in the epidural space can reach the nerve fibers in nerve roots at the same or neighboring lumbar segments. In this way, fibers not involved in the mechanical compression may be affected. METHODS: The small nerve fibers were studied using tests for thermal thresholds (thermotest), and the large myelinated fibers were studied by vibrametry. Forty-two patients were investigated in the symptomatic and the asymptomatic leg, and the results were compared with those of 21 healthy individuals. RESULTS: The thresholds of cold, warmth, and vibration were significantly increased in the dermatome of the compressed nerve root, indicating that large and small sensory nerve fibers were affected. Further, the thresholds were significantly increased in the neighboring dermatomes in the symptomatic and the asymptomatic leg. CONCLUSION: Large and small sensory afferent nerve fibers are affected in lumbar radiculopathy. The increase in sensation thresholds in the ipsilateral neighboring dermatome and in the dermatomes in the asymptomatic leg indicates that adjacent nerve roots are involved in the pathophysiology of sciatica in patients with lumbar disc herniation.     

Transpedicular fixation with Zielke instrumentation in the treatment of thoracolumbar and lumbar injuries

STUDY DESIGN: Sixty-five patients who underwent transpedicular fixation for thoracolumbar and lumbar injuries were studied for type of injury, the severity of paralysis, the degree of postoperative correction, and instrumentation failures. OBJECTIVES: To evaluate the surgical approaches and the selection of instrumentation to determine indications for using the transpedicular fixation procedure. SUMMARY OF BACKGROUND DATA: Various transpedicular fixation devices have been used for different type of injuries, and satisfactory postoperative results were not obtained in some studies. METHODS: Forty patients had burst fractures, 19 had fracture dislocations, and six had chance-type fractures. An anterior decompression procedure was used for most cases of burst fracture and some cases of fracture dislocation where anterior compression factors were present. The Zielke or modified Zielke system was used as an internal fixator for posterior segmental fixation. RESULTS: No patient had neurologic deterioration after surgery. Twenty of 28 patients with incomplete lesions improved postoperatively according to Frankel grades. The instrumentation failed in only one patient, in whom a nonunion developed. CONCLUSION: With transpedicular fixation, it is possible to provide solid internal fixation that is circumscribed to the injured vertebral segments. The elasticity of the Zielke rod makes it an excellent transpedicular fixation device because it is easily attached and reduction is easily performed. Anterior decompression with fusion needs to be used with transpedicular fixation in the treatment of injuries (especially burst fractures).     

CT myelography for diagnosis of brachial plexus avulsion in small animals

Avulsion of nerve roots of the brachial plexus can be diagnosed clinically, neurologically, radiographically and by electromyography. But like the myelography these techniques are inprecise for determination of the severity (partial or complete disruption) and the localization of the lesion. In human medicine the combination of computerized tomography with myelography shows high accuracy. Veterinary reports of experience in this field are not yet known. The aim of the present study was to demonstrate nerve root avulsions using myelography and computerized tomography. Three dogs and one cat with traumatic lesions of the brachial plexus were examined. The lesion could be seen in all patients. Thus CT-myelography results in an improved prognostic assessment of brachial plexus paralysis. Moreover, this technique could become one of the most important diagnostic methods for brachial plexus lesions involving nerve root reinsertion--neurotizations in veterinary medicine.     

Increased spike-frequency adaptation and tea sensitivity in dorsal root fibers after sciatic nerve injury

Excitability of rat dorsal root axons were studied 3 weeks after injury to the sciatic nerve. Whole nerve recordings were obtained from injured and control nerves in a sucrose gap chamber. Constant current depolarization pulses (30-200 ms) applied approximately 50% above the stimulus strength required for maximal amplitude compound action potentials (CAPs) evoked a burst of action potentials in the dorsal root which displayed spike adaptation. The depolarization-induced burst response of the dorsal roots was greatly reduced after crush or transection of the sciatic nerve. However, application of the potassium channel blocker, tetraethylammonium (TEA), restored the burst discharge in injured dorsal root axons. Brief tetanic stimulation of the dorsal root also induced an afterhyperpolarization (AHP) that was twice as large in the transection group as compared to the control group, and which was blocked by TEA. There were no changes seen in the amplitude of the compound action potential, frequency-following characteristics, refractory properties, or 4-AP sensitivity in the dorsal roots after peripheral nerve injury. These results suggest that there is enhanced spike adaptation that occurs at the same time as an increase in the sensitivity to the potassium channel blocker, TEA, in axon regions proximal to the site of nerve injury and have implications for the pathophysiology of nerve injury.     

1997 Volvo Award winner in clinical studies. Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective, randomized study comparing decompressive laminectomy and arthrodesis with and without spinal instrumentation

STUDY DESIGN: This prospective study analyzed the influence of transpedicular instrumented on the operative treatment of patients with degenerative spondylolisthesis and spinal stenosis. OBJECTIVES: To determine whether the addition of transpedicular instrumented improves the clinical outcome and fusion rate of patients undergoing posterolateral fusion after decompression for spinal stenosis with concomitant degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: Decompression is often necessary in the treatment of symptomatic patients who have degenerative spondylolisthesis and spinal stenosis. Results of recent studies demonstrated that outcomes are significantly improved if posterolateral arthrodesis is performed at the listhesed level. A meta-analysis of the literature concluded that adjunctive spinal instrumentation for this procedure can enhance the fusion rate, although the effect on clinical outcome remains uncertain. METHODS: Seventy-six patients who had symptomatic spinal stenosis associated with degenerative lumbar spondylolisthesis were prospectively studied. All patients underwent posterior decompression with concomitant posterolateral intertransverse process arthrodesis. The patients were randomized to a segmental transpedicular instrumented or noninstrumented group. RESULTS: Sixty-seven patients were available for a 2-year follow-up. Clinical outcome was excellent or good in 76% of the patients in whom instrumentation was placed and in 85% of those in whom no instrumentation was placed (P = 0.45). Successful arthrodesis occurred in 82% of the instrumented cases versus 45% of the noninstrumented cases (P = 0.0015). Overall, successful fusion did not influence patient outcome (P = 0.435). CONCLUSIONS: In patients undergoing single-level posterolateral fusion for degenerative spondylolisthesis with spinal stenosis, the use of pedicle screws may lead to a higher fusion rate, but clinical outcome shows no improvement in pain in the back and lower limbs.     

Omega-3 fatty acids in the prevention-management of cardiovascular disease

Eight cervical spines were used to evaluate the relation of the screw tip to the nerve root in the intervertebral foramen. The specimens were divided into two groups: (a) lateral placement without contact with the nerve root, and (b) lateral placement with penetration of the nerve root. Six screws were used for each specimen. After screw placement, oblique radiographs and axial computed tomography (CT) scans were taken. The results on oblique radiographs showed that 23 (95.8%) of 24 screws without contact with the nerve root were found in the upper zone or the junction between the upper and lower zones of the intervertebral foramen. Twenty (83.3%) of 24 screws with penetration of the nerve root were located in the junction between the lower zone of the intervertebral foramen and the pedicle zone. No definite diagnosis of screw penetration of the nerve root could be made on axial CT scans, although scans can show that the screw is violating the foramen. Whether or not a screw violating the intertransverse foramen and affects the nerve root depends on its position on the oblique radiograph. It may be not necessary to remove or change the screw immediately if a longer screw is found in the upper portion of the intervertebral foramen on the oblique view and angled laterally on axial CT scan in a patient without radicular symptoms.     

Stability of posterior spinal instrumentation and its effects on adjacent motion segments in the lumbosacral spine

STUDY DESIGN: An in vitro biomechanical analysis of three anterior instability patterns was performed using calf lumbosacral spines. Stiffness of the constructs was compared, and segmental motion analyses were performed. OBJECTIVES: To clarify the factors that alter the stability of the spinal instrumentation and to evaluate the influence of instrumentation on the residual intact motion segments. SUMMARY OF BACKGROUND DATA: Recently, many adverse effects have been reported in fusion augmented with rigid instrumentation. Only few reports are available regarding biomechanical effects of stability provided by spinal instrumentation and its effects on residual adjacent motion segments in the lumbar-lumbosacral spine. METHODS: Eighteen calf lumbosacral spine specimens were divided into three groups according to instability patterns--one-level, two-level, and three-level disc dissections. Six constructs were cyclically tested in rotation, flexion-extension, and lateral bending of intact spines, of destabilized spine, and of spines with four segmental posterior instrumentation systems used to extend the levels of instability (Cotrel-Dubousset compression hook and three transpedicular screw fixation systems). During each test, stiffness values and segmental displacements were measured. RESULTS: The rigidity of the instrumented construct increased as the fixation range became more extensive. Although application of the instrumentation effectively reduced the segmental motion of the destabilized vertebral level, the motion at the destabilized level tended to increase as the number of unstable vertebral levels increased, and the fixation range of the instrumentation became more extensive. Instrumented constructs produced higher segmental displacement values at the upper residual intact motion segment when compared with those of the intact spine. In contrast, the instrumented constructs decreased their segmental displacement values at the lower residual intact motion segment with higher magnitude of the translational (shear) motion taking place compared with the intact spine in flexion-extension and lateral bending. These changes in the motion pattern became more distinct as the fixation range became more extensive. CONCLUSIONS: As segmental spinal instrumentation progresses from one level to three levels, the overall torsional and flexural rigidity of the system increases. However, segmental displacement at the site of simulated instability becomes more obvious. Application of segmental instrumentation changes the motion pattern of the residual intact motion segments, and the changes in the motion pattern become more distinct as the fixation range becomes more extensive and as the rigidity of the construct increases.     

Anterior transpedicular fixation of the lower thoracic and lumbar spine. Experimental verification using a new direction finder

Currently, no anterior spinal implant provides a strong bone-screw interface because of the cancellous characteristics of the vertebral body. A more secure anchorage could be obtained by anterior transpedicular screw fixation. Four hundred transpedicular screws located between T7 and L5 were placed using the newly developed direction finder. Measurements were obtained directly from radiographs of the cadaveric specimens. In 10 cases (2.5%), the screws crossed the medial pedicle border, but never by more than 1.4 mm. A lateral protrusion was noted in another 41 screws (10%), with no protrusion greater than 2.2 mm. Encroachments beyond the superior or inferior border were not observed. The mean angle of the screws at each level measured between 7 and 19 in the transverse plane and between 2 and 4.5 in the sagittal plane. This technique should be reserved for vertebrae without significant arthritic changes. The rare screw with minimal infraction through the medial or lateral pedicle wall should not cause any vascular or neural compromise. The anterior transpedicular screw technique appeared relatively safe (88%) and encouraged the development of the new plate system for anterior spinal stabilization.     

Neuropathy presenting as prolonged dyspnea. Case report and review of literature

Polyneuropathy presented as isolated respiratory muscular paralysis. Transdiaphragmatic pressure measurements, nerve conduction studies, electromyography, and biopsy of intercostal muscle confirmed the nature of the process. Patients with unexplained respiratory insufficiency must be carefully evaulated for underlying neuromuscular disease.     

Direct evidence of parasympathetic vasodilatation in cat periodontal ligament

Sympathetic regulation of periodontal ligament blood flow (PLBF) is well-attested; however, vasodilator responses mediated by parasympathetic nerve fibers have yet to be conclusively demonstrated in the periodontal ligament (PL). The present study was designed to determine whether parasympathetic vasodilator mechanisms do or do not exist in the cat PL. In our cats, the cervical sympathetic trunks were sectioned bilaterally prior to any stimulation in order to eliminate sympathetic effects on the vascular beds under study. Dynamic changes in PLBF, with mandibular lip blood flow (LBF) recorded for comparison, were investigated in cat mandibular canine teeth using laser Doppler flowmetry. The peripheral cut ends of the facial and glossopharyngeal nerve roots, which have been reported to contain parasympathetic nerve fibers to the oral tissues, were electrically stimulated intracranially. Such stimulation caused blood flow to increase in the ipsilateral PL and lip, without an increase in systemic blood pressure. These vasodilator responses in the PL and lip were sensitive to ganglion blockade (with hexamethonium), indicating vasodilation via activation of parasympathetic vasodilator fibers. In contrast, although intracranial stimulation of the trigeminal nerve root also induced increases in both PLBF and LBF, these were unaffected by hexamethonium, but reduced by tripelennamine, indicating antidromic vasodilatation via the trigeminal sensory nerve. These results suggest that parasympathetic vasodilator mechanisms do exist in feline PL.     

Complications of pediatric thoracolumbar and lumbar pedicle screws

STUDY DESIGN: This was a retrospective review of 223 consecutive cases (1986-1996) from one institution where 759 thoracolumbar and lumbar pedicle screws were used in the treatment of various pediatric spinal disorders in patients less than 18 years of age. OBJECTIVES: To determine the incidence of short- and long-term (> 2 years follow-up) complications in this group of patients-specifically, complications related to instrumentation and those directly attributable to pedicle screws in these pediatric patients. SUMMARY OF BACKGROUND DATA: Although much has been written regarding the use of pedicle screws in the adult population, no published study has examined complication rates with regard to thoracolumbar and lumbar pedicle screws placed for pediatric spinal disorders. METHODS: A retrospective review of 223 consecutive cases involving 759 pedicle screws placed for a variety of pediatric spinal disorders was performed. Complications were divided into short term and long term (> 2 years follow-up) and into those relating to instrumentation and those relating to pedicle screws specifically. RESULTS: Short-term complication occurred in 5 patients (2.2%) for a total of 17 screws ultimately removed. Only two of these patients had screws removed for lumbar radicular complaints. No residual sequellae resulted. No long-term (> 2 years postoperative) complications were noted. CONCLUSION: Low short- and long-term complication rates specific for pediatric pedicle screws suggests that for properly trained spinal surgeons, pedicle screws fixation in the pediatric population can be performed safely to treat a variety of spinal disorders.     

Succinylcholine-induced hyperkalemia following prolonged pharmacologic neuromuscular blockade

While being treated for the acute respiratory distress syndrome, a 27-year-old woman developed profound hyperkalemia and cardiac arrest following the administration of succinylcholine chloride (SCh). She had none of the risk factors previously described for development of severe hyperkalemia following SCh administrations; however, she had been intermittently treated with nondepolarizing neuromuscular blocking drugs throughout the course of her illness. We suggest that immobilization of critically ill patients with pharmacologic neuromuscular blockade may predispose them to severe hyperkalemia and cardiac arrest following administration of SCh. SCh should be used with great caution in such patients.     

Post transfusion non-cardiogenic pulmonary edema in a patient with chemotherapy-related hemolytic uremic syndrome

Recent experimental studies performed at the Dept of Orthopaedics at Gothenburg University have systematically assessed the basic pathophysiological mechanisms behind sciatica due to disc herniation. It has hereby been seen that the epidural presence of nucleus pulposus may induce structural and functional injury of the adjacent nerve roots similar in magnitude to those induced by mechanical deformation. By increasing the knowledge of the substances and mechanisms leading to this nucleus pulposus-induced nerve injury it may be assumed that sciatica to a certain extent may be treated by specific pharmacologic agents in the future, in combination with existing treatment modalities.     

Delay of clinical recovery from paralysis induced by atracurium: comparison between orbicularis oculi and adductor pollicis

OBJECTIVE: To compare with train-of-four stimulation the delays of the beginning of the spontaneous recovery of the orbicularis oculi and of the adductor pollicis after profound neuromuscular blockade with atracurium. STUDY DESIGN: Prospective, comparative open study. PATIENTS AND METHODS: Twenty-eight physical class ASA 1 and 2 patients under general anaesthesia (propofol, N2O, fentanyl) and profound neuromuscular blockade with atracurium. Train-of-four stimulation, every 10 s, of the ulnar nerve at the wrist (for assessing by tactile means the response of the adductor pollicis) and of the temporal branch of the facial nerve (for assessing visually the response of the orbicularis oculi). On each site, measurement of the delay between the end of the maintenance of deep neuromuscular blockade (last dose of atracurium) and the beginning of the recovery (first response to train-of-four stimulation). RESULTS: In each case, the recovery of the orbicularis oculi began earlier than the recovery of the adductor pollicis (26 +/- 9 min vs 34 +/- 9 min, P < 0.001). The delays of recovery at each site were strongly correlated (r = 0.87; P < 0.001) but the time lag between the responses varied greatly: 1 to 21 min, mean: 8 +/- 5 min, coefficient of variation: 56.6%. CONCLUSION: The orbicularis oculi should not be monitored alone for assessment of recovery from profound neuromuscular blockade by atracurium, as it predicts poorly the time of the recovery of the adductor pollicis.