Whiplash: a review of a commonly misunderstood injury.

Whiplash injury is a relatively common occurrence, but its mechanism and optimal treatment remain poorly understood. It is estimated that the incidence of whiplash injury is approximately 4 per 1,000 persons. The most common radiographic findings include either preexisting degenerative changes or a slight flattening of the normal lordotic curvature of the cervical spine. Computed tomography and magnetic resonance imaging are generally reserved for cases of neurologic deficit, suspected disc or spinal cord damage, fracture, or ligamentous damage. Biomechanics studies have determined that after rear impact C6 is rotated back into extension before movement of the upper cervical vertebrae. Thus, the lower cervical vertebrae were in extension while the upper vertebrae were in a position of relative flexion, producing an S shape in the cervical spine. It is believed that this abnormal motion pattern might play a role in the development of whiplash injuries. Historically, a soft cervical collar has been used early after the injury in an attempt to restrict cervical range of motion and limit the chances of further injury. More recent studies report rest and restriction of motion to be detrimental and to slow the healing process.

Interleukin-2-dependent T lymphocytes for the diagnosis and investigation of inherited metabolic disorders.

Interleukin-2-dependent T cell lines can be started from as little as 1 ml of peripheral blood and expanded to 50 x 10(6) cells within 12 days. These cells represent an easily obtainable source of nucleated tissue with certain advantages over skin fibroblasts or transformed B lymphoblastoid cells for the rapid diagnosis and study of inherited metabolic disorders. A panel of 19 enzymes were assayed in IL-2-dependent T lymphocytes and the diagnosis of four enzyme deficiencies is demonstrated using T lymphocytes.

Effects of introspecting about reasons: inferring attitudes from accessible thoughts.

Previous research has shown that analyzing reasons can change people's attitudes, but the exact mechanisms of this effect have not been entirely clear. It was hypothesized that introspecting about reasons focuses people's attention on thoughts that are accessible in memory and increases the extent to which people view their accessible thoughts as applicable to their current attitudes. In Study 1, college students formed initial impressions of a target person, and then positive or negative thoughts about the target person were made memorable. After a delay, half of the participants analyzed reasons for their attitude and half recalled the target person's behaviors. As predicted, people who analyzed reasons reported attitudes toward the target person that were based more on what they could recall about her. Study 2 showed that this effect occurs regardless of whether people initially form an online impression. Implications for the effects of analyzing reasons and for attitude formation are discussed.

Complications of myelography after partial metrizamide withdrawal.

Lumbar metrizamide myelography (LMM) has been associated with a high incidence of side effects. A total of 94 patients underwent LMM for suspected disc disease or spinal stenosis. In Group 1 a 22-gauge spinal needle was used. Containing the same amount and concentration of metrizamide, an 18-gauge spinal needle was used in Group 2 after which there was partial withdrawal of the metrizamide (average withdrawal: 73%). In Group 1 a total of 38% of patients experienced one side effect whereas 8.5% had two side effects. In Group 2 a total of 8.5% of patients experienced one side effect and 4.25% had two side effects. This study demonstrates a statistically (P less than 0.003) lower incidence of side effects with metrizamide withdrawal after myelography.

Extradural synovial thoracic cyst.

SUMMARY OF BACKGROUND DATA. Case studies documenting the incidence of thoracic intraspinal, extradural synovial cysts are limited. The occurrence of synovial cysts is associated with varied symptoms that differ among cervical, thoracic, and lumbar regions. The clinical appearance may be similar to other spinal diseases. METHODS. This report describes symptoms exhibited by and care provided for a patient with extradural synovial thoracic cyst.

The natural history of the cervical foramen in symptomatic and asymptomatic individuals aged 20-60 years as measured by magnetic resonance imaging. A descriptive approach.

STUDY DESIGN: This study was intended to identify normal degenerative morphologic evolution in the bony foramen in asymptomatic subjects by decade in comparison with symptomatic subjects of like decades. OBJECTIVES: To determine normal degenerative changes in the cervical spine caused by the aging process that predispose a person to foraminal stenosis and radiculopathy. SUMMARY OF BACKGROUND DATA: Cervical radiculopathy is a common problem caused by degenerative changes as people age. The characteristics of the foramen that result in stenosis are not known. METHODS: Five to six symptomatic and asymptomatic people in each decade volunteered for magnetic resonance imaging. Lordosis, disc heights, and ratio of spinal cord diameter to spinal canal diameter were measured at C4-C5, C5-C6, and C6-C7 from sagittal magnetic resonance images. Foraminal heights, widths, and areas were measured at the isthmus of the same foramen from oblique images. RESULTS: Foraminal heights, widths, and areas were larger in asymptomatic patients than in symptomatic patients. Morphologic analysis showed that inferior facet hypertrophy tended to decrease the width of the foramen in aging people. Disc heights, lordosis, and ratio of spinal cord diameter to spinal canal diameter showed no significant differences. CONCLUSIONS: Foraminal height affects overall foraminal area but tends to change little with age. Width also affects overall area and not only decreases in older people but also significantly affects the available area for the exiting nerve root.

Cervical epidural steroid injection with intrinsic spinal cord damage. Two case reports.

STUDY DESIGN: Intrinsic cervical spinal cord damage represents the serious and permanent complications that can occur if cervical epidural steroid injections are administered while the patient is sedated. Two case reports are presented. OBJECTIVES: To draw attention to the dangerous consequences that can arise from sedating a patient before administering a cervical epidural steroid injection. SUMMARY OF BACKGROUND DATA: Reported complications of cervical epidural steroid injections have been minor and infrequent. No reports of intrinsic cervical cord damage could be found in a comprehensive English language literature search. METHODS: Two case reports of permanent intrinsic cervical cord damage in patients who had been administered cervical epidural steroid injections while under intravenous sedation are presented. Magnetic resonance imaging was performed before and after the administration of cervical epidural steroid injections. Each patient had herniated nucleus pulposus before they received cervical epidural steroid injections and intrinsic cord damage on postinjection magnetic resonance images. RESULTS: Both patients developed increased pain and neurologic symptoms within 24 hours of injection. To date, these symptoms appear to be permanent. However, Patient 1 had pain relief in her right arm and shoulder after undergoing a microdiscectomy, but pain was still persistent in her left leg, and she has developed a positive Lhermitte's sign. CONCLUSION: These case reports indicate fluoroscopic guidance will not insure or prevent intrathecal perforation or spinal cord penetration during the administration of cervical epidural steroid injections. In addition, although intravenous sedations during cervical epidural steroid injections have been used numerous times without reported complications, it appears intravenous sedation in these two cases resulted in the inability of the patient to experience the expected pain and paresthesias at the time of spinal cord irritation. Therefore, the authors conclude that the patient should be fully awake during the administration of cervical epidural steroid injections, with only local anesthetic in the skin used for analgesia.

Management of incidental durotomy without mandatory bed rest. A retrospective review of 20 cases.

STUDY DESIGN: A retrospective review of 20 patients with incidental durotomy treated without mandatory bed rest. OBJECTIVES: To determine whether patients with incidental durotomy can be treated effectively without multiple days of bed rest. SUMMARY OF BACKGROUND DATA: Incidental durotomy can cause postural headaches, nausea, vomiting, dizziness, photophobia, tinnitus, and vertigo. These symptoms are believed to result from a decrease in cerebrospinal fluid pressure, leading to traction on the supporting structures of the brain. Traditional management includes bed rest for up to 7 days to eliminate traction and reduce hydrostatic pressure during the healing process. METHODS: Twenty incidental durotomies were repaired intraoperatively with dural stitches and fibrin glue. Patients were allowed to ambulate according to the natural course after surgery without mandatory bed rest. Symptoms were monitored closely for 1 week, and long-term follow-up assessments were obtained at a minimum of 10 months. RESULTS: Of the 20 patients in this study, 75% had no symptoms after repair of the incidental durotomy. Each of the dural tears was 1-3 mm in length. Two patients reported headache, two reported nausea, and one reported tinnitus; no patients experienced vomiting. One patient (5%) had stitch loosening requiring revision surgery. There were no additional serious complications. CONCLUSIONS: This study has shown that the majority of patients with incidental durotomy can be treated effectively with dural stitches and fibrin glue. Patients can be permitted to ambulate immediately after surgery but should be cautioned to lay flat if they develop symptoms. This will reduce the costs related to the hospital stay and missed work.

The surgical treatment of far lateral L3-L4 and L4-L5 disc herniations. A modified technique and outcomes analysis of 25 patients.

STUDY DESIGN: A retrospective review of 25 patients who underwent a modified surgical procedure for the treatment of far lateral disc herniation. OBJECTIVES: To describe a modification of previous surgical techniques for the treatment of far lateral disc herniation and to review the outcomes in resolution of pain and improvement of functional status. SUMMARY OF BACKGROUND DATA: Lumbar disc herniations that occur far lateral to the intervertebral facet result in spinal nerve compression at L3-L4 and L4-L5. Previous surgical techniques have resulted in an increased risk of instability or continued postoperative back pain. METHODS: Twenty-five patients with far lateral disc herniation underwent surgery using an extreme lateral approach. There was no medial facetectomy or disruption of the pars interarticularis. The intertransverse ligament was released from the superior portion of the inferior transverse process, and the nerve was located before removal of the disc. Preoperative and postoperative visual analog pain scale and Oswestry functional status evaluation were reviewed along with complications to evaluate the efficacy of the surgery. RESULTS: No serious complications were noted, although transient neuropathic pain was common and was theorized to be caused by manipulation of the dorsal root ganglion during surgery. This pain was usually resolved within 4 to 6 weeks. The mean preoperative and postoperative visual analog scale scores were 7.7 and 4.2, respectively. The mean preoperative and postoperative Oswestry scores were 50.7% and 34.7%, respectively. Both of these improvements were statistically significant (P < 0.01). CONCLUSIONS: This far lateral approach allowed the nerve and far lateral disc herniations to be easily identified. Also, there was less blood loss and no medial facetectomy or disruption of the pars interarticularis. This is a safe, effective technique with no disruption of spinal stability.

Reliability of magnetic resonance imaging in predicting disc material posterior to the posterior longitudinal ligament in the cervical spine. A prospective study.

STUDY DESIGN: This was a prospective study to evaluate the accuracy of magnetic resonance imaging in predicting the presence of disc material posterior to the posterior longitudinal ligament (PLL), compared with the accuracy of intraoperative visual and tactile examination of the PLL. OBJECTIVES: To determine the accuracy of magnetic resonance imaging in predicting the presence of disc material posterior to the PLL. SUMMARY OF BACKGROUND DATA: Whether removal of the disc to the PLL is sufficient when performing an anterior cervical discectomy and fusion or it is necessary to explore the spinal canal by taking down the PLL is controversial. METHODS: Fifty-four cervical levels were examined by magnetic resonance imaging before surgery to determine whether there was disc material posterior to the PLL. During surgery, the PLL was examined and probed for disruption. The ligament was taken down, and free fragments were identified and removed. RESULTS: Of 54 levels, 12 were correctly identified by magnetic resonance imaging as having disc material posterior to the PLL, and 26 were correctly identified as not having disc material posterior to the PLL. Surgery confirmed that at 26 levels there was disc material posterior to the PLL. Of these 26, 23 (88.5%) had visual or palpable disruption of the PLL. Magnetic resonance imaging failed to predict disc material posterior to the PLL in 14 of the cases in which its presence was confirmed during surgery. Magnetic resonance imaging had 46.2% sensitivity and 92.9% specificity rates. CONCLUSIONS: Because of low sensitivity, magnetic resonance imaging should be used cautiously for predicting free disc material posterior to the PLL. Visual or palpable examination of the PLL during surgery is more accurate for this prediction.

Comparison of posterior and transforaminal approaches to lumbar interbody fusion.

STUDY DESIGN: A study of the transforaminal lumbar interbody fusion and the posterior lumbar interbody fusion techniques was performed. OBJECTIVES: To describe the transforaminal lumbar interbody fusion technique, and to compare operative data, including blood loss and operative time, with data from posterior lumbar interbody fusion technique. SUMMARY OF BACKGROUND DATA: The evolution of posterior lumbar fusion combined with anterior interbody fusion has resulted in increased fusion rates as well as improved reductions and stability. The transforaminal lumbar interbody fusion technique pioneered by Harms and Jeszensky offers potential advantages and provides a surgical alternative to more traditional methods. METHODS: In 13 consecutive months, two spinal surgeons performed 40 transforaminal lumbar interbody fusions and 34 posterior lumbar interbody fusion procedures. Data regarding blood loss, operative times, and length of hospital stay were recorded. These data were analyzed using analysis of variance to show any significant differences between the two techniques. To determine whether differences in measured variables were dependent on patient gender or number of levels fused, epsilon(chi2) analysis was used. RESULTS: No significant differences were found between transforaminal and posterior lumbar interbody fusions in terms of blood loss, operative time, or duration of hospital stay when a single-level fusion was performed. Significantly less blood loss occurred when a two-level fusion was performed using the transforaminal approach instead of the posterior approach (P < 0.01). Differences in measured variables for the two procedures were independent of patient age, gender, and the number of levels fused. There were no complications with the transforaminal approach, but the posterior approach resulted in multiple complications. CONCLUSIONS: In this comparison of patients receiving transforaminal lumbar interbody fusion versus posterior lumbar interbody fusion, no complications occurred with the transforaminal approach, whereas multiple complications were associated with the posterior approach. Similar operative times, blood loss, and duration of hospital stay were obtained in single-level fusions, but significantly less blood loss occurred with the transforaminal lumbar interbody approach in two-level fusions. The transforaminal procedure preserves the interspinous ligaments of the lumbar spine and preserves the contralateral laminar surface as an additional surface for bone graft. It may be performed at all lumbar levels because it avoids significant retraction of the dura and conus medullaris.

Load-carrying capacity of the human cervical spine in compression is increased under a follower load.

STUDY DESIGN: An experimental approach was used to test human cadaveric cervical spine specimens. OBJECTIVE: To assess the response of the cervical spine to a compressive follower load applied along a path that approximates the tangent to the curve of the cervical spine. SUMMARY OF BACKGROUND DATA: The compressive load on the human cervical spine is estimated to range from 120 to 1200 N during activities of daily living. Ex vivo experiments show it buckles at approximately 10 N. Differences between the estimated in vivo loads and the ex vivo load-carrying capacity have not been satisfactorily explained. METHODS: A new experimental technique was developed for applying a compressive follower load of physiologic magnitudes up to 250 N. The experimental technique applied loads that minimized the internal shear forces and bending moments, loading the specimen in nearly pure compression. RESULTS: A compressive vertical load applied in the neutral and forward-flexed postures caused large changes in cervical lordosis at small load magnitudes. The specimen collapsed in extension or flexion at a load of less than 40 N. In sharp contrast, the cervical spine supported a load of up to 250 N without damage or instability in both the sagittal and frontal planes when the load path was tangential to the spinal curve. The cervical spine was significantly less flexible under a compressive follower load compared with the hypermobility demonstrated under a compressive vertical load (P < 0.05). CONCLUSION: The load-carrying capacity of the ligamentous cervical spine sharply increased under a compressive follower load. This experiment explains how a whole cervical spine can be lordotic and yet withstand the large compressive loads estimated in vivo without damage or instability.

Predicting factors of successful recovery from lumbar spine surgery among workers' compensation patients.

It is commonly believed that patients who are compensated for a work-related injury have less incentive to return to work. This study evaluated how various factors affected the outcomes of lumbar spine surgery in terms of pain relief, functional status, return to work, and general health. Eighty-seven workers' compensation patients had spinal fusion or microdiskectomy. Subjects were evaluated preoperatively and postoperatively using the Oswestry disability scale and the Visual Analog Scale for Pain. The type of surgery performed significantly affected patient outcomes, while such factors as gender, age, smoking, and litigation were insignificant. Microdiskectomy patients, for example, had greater reduction in pain and disability than did fusion patients (P < .01). Return-to-work status was negatively affected by fusion (P < .01). Overall, 55% of patients did return to work in some capacity, but the rate was 72% for microdiskectomy patients versus 43% for fusion patients. While outcomes significantly improved, postoperative scores remained severe. This did not correlate with return-to-work rates, suggesting that outcomes measures may not be effective.

Techniques for stimulating spinal fusion: efficacy of electricity, ultrasound, and biologic factors in achieving fusion.

Many advancements have been made in an attempt to decrease the rate of pseudoarthrosis. Some of these have involved the actual fusion surgery. Fusions with internal fixation devices are able to more effectively eliminate motion during the healing process, thus leading to increased fusion rates. Electrical stimulation and ultrasound were initially developed to aid in fracture healing, but have shown to be efficacious in spinal fusion, as well. Biologic growth factors have long been known to control the bone growth process. These proteins have been identified and isolated for use in augmenting spinal fusion. The discovery of bone morphogenetic protein has great promise in significantly improving fusion rates over the use of either allograft or autograft.

Adjacent-segment degeneration after lumbar fusion: a review of clinical, biomechanical, and radiologic studies.

Lumbar fusion is commonly performed to relieve pain from degenerative conditions, including spinal stenosis and spondylolisthesis. While clinical studies have reported favorable fusion rates with limited complications, few have investigated the effect of fusion on the adjacent motion segment. A solid fusion alters the biomechanics at the adjacent level, resulting in increased mechanical demands. There have been reports of increased rates of adjacent-level pathologic lesions after fusion, but these have not accounted for the natural history of degenerative changes. Biomechanical and radiographic studies have shown increased forces, mobility, and intradiscal pressure in adjacent segments after fusion. It has been hypothesized that these changes lead to an acceleration in pathologic changes.

Bovine beta-mannosidase deficiency.

A fatal inherited glycoprotein storage disorder is described in Salers cattle which affects both sexes. Affected calves are unable to stand at birth, have a marked intention tremor, markedly enlarged kidneys, decreased white matter in all areas of the brain, and cytoplasmic vacuolation in multiple cell types of multiple tissues with nervous, renal, lymphoid and thyroid tissues most severely affected. Affected calves were grossly deficient in lymphocyte and brain beta-mannosidase activity and had markedly reduced but not deficient activity in liver and kidney. A test mating of obligate carriers produced three genotypes: affected, carrier, non-carrier in essentially the expected ratio of 1:2:1, consistent with autosomal recessive inheritance.

Intraoperative loosening of Bagby and Kuslich cages during anterior lumbar interbody fusion.

The Bagby and Kuslich (BAK) interbody fusion system has been shown to be a safe and effective method for obtaining solid fusion while maintaining lumbar lordosis. Although postoperative cage loosening has been reported, intraoperative cage loosening has not. The authors describe three cases in which BAK cages became loosened during operation. After the first BAK cage was inserted, it appeared to be well positioned and firmly seated; after placement of the second cage, however, the first cage was loose. Each of these cages was replaced without incident and appeared well placed on follow-up. It is crucial for the surgeon to verify that all cages are firmly seated before closure. This may reduce the incidence of postoperative cage migration.