Conservative treatment of fragility fracture of the pelvis: A retrospective study.

BACKGROUND: Although an increasing number of studies have reported the usefulness of early minimally invasive surgery (MIS) or fragility fracture of the pelvis (FFP), MIS is difficult to perform in every hospital, partly because of equipment problems. Moreover, different opinions exist on FFP treatment methods and the indication for surgery is usually determined by the fracture type. Since our hospital follows a conservative approach as the basic treatment, this study examined the outcomes of such an FFP approach. HYPOTHESIS: FFP outcomes are influenced by the fracture type and walking ability before the injury. PATIENTS AND METHODS: We investigated the bone fusion rate, bone fusion duration, unloading duration, walking ability trends, and outcomes in 76 patients with FFP treated conservatively at our hospital. RESULTS: The union rate, mean period until union, and follow-up period were 93.4%, 3.3 months, and 14.3 months, respectively. Walking ability significantly decreased from 5.1 points before the injury to 4.4 points during the last follow-up (p<0.01). The average unloading period was 12.8 days, and FFPs showed a high bone fusion rate, even with conservative treatment. DISCUSSION: Most patients eventually returned to their pre-injury status despite slightly decreased walking ability. Given the invasive nature of surgery, the indications for surgery should be carefully assessed after considering the risk-benefit ratio. LEVEL OF EVIDENCE: III; retrospective study.

Application of a Navigated Drill for Cervical Pedicle Screw Insertion at C3-6.

Background Perforation of the cervical pedicle screw, especially lateral perforation, may lead to critical complications, such as vertebral artery injury. Sub-axial cervical spines (C3-6) are at risk of complications because these levels have limited area and angle. This study aimed to compare a navigated drill and a navigated probe for the insertion of cervical pedicle screws at C3-6. Methodology This retrospective study included 106 patients treated with cervical pedicle screws at C3-6. In total, 52 patients with 200 cervical pedicle screws using a navigated drill (group D) and 54 patients with 170 cervical pedicle screws using a navigated probe (group P) were compared. The perforation rate, anatomical medial angle of the pedicle, and actual angle of the screw were investigated using computed tomography. The planning error was defined as when the pedicle screw was applied for a small pedicle width of <3.5 mm. All perforations except for planning errors were defined as technical perforations. Results Grade 1 screw perforations were identified in 16 and 17 screws in groups D and P, respectively. Overall, 88% of the perforations were medial in group D, and 82% of perforations were lateral in group P. Technical perforations were found in 7/191 (3.7%, group D) and 15/168 (8.9%, group P) screws. There were no significant differences in the anatomical angle of the pedicle between the groups. The mean medial angle of the pedicle screws was 24.7° (group D) and 30.9° (group P) (p < 0.05). Conclusions The perforation rate of group D was less than half of that of group P. This was because a navigated drill was able to create a bony pilot hole at the hard medial cortical wall of the pedicle with a small medial angle, which was difficult to do with a navigated probe. A navigated drill can be useful for cervical pedicle screw insertion at C3-6 because of its easiness and safety.

Pneumocephalus After Anterior Lumbar Spinal Surgery Due to Trauma: A Case Report.

Pneumocephalus as a complication of anterior lumbar spinal surgery is extremely rare. A 53-year-old male patient presented with L4 fracture. Posterior fixation from L3 to L5 was conducted one day after the trauma. As the patient's neurological deficit persisted, additional anterior surgery by L4 vertebral body replacement was performed on the 19th day. Both surgeries were completed without obvious intraoperative complications. Two weeks after the anterior lumbar surgery, the patient complained of severe headaches, and computed tomography scan revealed pneumocephalus and massive fluid retention in the abdomen. The symptoms improved with conservative treatment, including bed rest, spinal drainage, intravenous drip infusion, and prophylactic administration of antibiotics. Due to the lack of tamponade effect in the soft tissues, a large amount of cerebrospinal fluid leakage may induce and cause progression of pneumocephalus in anterior dural injury.

Minimally invasive surgery technique for unstable pelvic ring fractures with severe vertical shear displacement: A retrospective study.

BACKGROUND: Unstable pelvic fractures, especially vertical shear fractures, require surgery for correct reduction, rigid fixation, and improved postoperative outcomes. Herein, we assess the effectiveness of our minimally invasive procedure for the management of unstable pelvic fractures. HYPOTHESIS: We hypothesized that this procedure would be useful for the management of unstable pelvic fractures. PATIENTS AND METHODS: This study included 28 patients with unstable pelvic fractures (vertical shear injuries; AO types C1-3) treated using minimally invasive surgery for spinopelvic fixation (MIS-SP) between 2014 and 2020 (mean follow-up time, 15 months). The MIS-SP requires four percutaneous pedicle screws and four iliac screw insertions. Subsequently, reduction and fixation are performed. RESULTS: The mean preoperative displacement of the posterior pelvic elements in craniocaudal correction was 17.6 (range, 9.0-32.2) mm. The mean length of the craniocaudal reduction was 16.5 (8.1-30.1) mm, with a mean reduction rate of 93.5% (78%-100%). The mean length of the mediolateral reduction was 11.3 (3.9-19.6) mm, with a mean reduction rate of 87.3% (76%-100%). DISCUSSION: Our novel reduction and fixation procedure is a powerful, minimally invasive option for the treatment of unstable pelvic ring fractures. LEVEL OF EVIDENCE: III.

Mechanical Study of Various Pedicle Screw Systems including Percutaneous Pedicle Screw in Trauma Treatment.

Background and Objectives: Spine surgery using a percutaneous pedicle screw placement (PPSP) is widely implemented for spinal trauma. However, percutaneous systems have been reported to have weak screw-rod connections. In this study, conventional open and percutaneous systems were biomechanically evaluated and compared. Material and Methods: The experiments were performed in two stages: the first stage was a break test, whereas the second stage was a fatigue test. Four systems were used for the experiments. System 1 was intended for conventional open surgery (titanium rod with a 6.0 mm diameter, using a clamp connecting mechanism). System 2 was a percutaneous pedicle screw (PPS) system for trauma (titanium alloy rod with a 6.0 mm diameter, using ball ring connections). System 3 was a PPS system for trauma (cobalt-chromium alloy rod with a 6.0 mm diameter, using sagittal adjusting screw connections). System 4 was a general-purpose PPS system (titanium alloy rod with a 5.5 mm diameter, using a mechanism where the adapter in the head holds down the screw). Results: Stiffness values of 54.8 N/mm, 43.1 N/mm, 90.9 N/mm, and 39.3 N/mm were reported for systems 1, 2, 3, and 4, respectively. The average number of load cycles in the fatigue test was 134,393, 40,980, 1,550,389, and 147,724 for systems 1 to 4, respectively. At the end of the test, the displacements were 0.2 mm, 16.9 mm, 1.2 mm, and 8.6 mm, respectively. System 1, with a locking mechanism, showed the least displacement at the end of the test. Conclusion: A few PPS systems showed better results in terms on stiffness and life than the open system. The experiments showed that mechanical strength varies depending on the spinal implant. The experiments conducted are essential and significant to provide the mechanical strength required for surgical reconstruction.

Long-Term Results of Posterior Vertebral Column Resection for Severe Thoracolumbar Kyphosis with Achondroplastic Patients: A Case Series.

Background and Objectives: Thoracolumbar kyphosis is one of the most frequent skeletal manifestations in patients with achondroplasia. Few papers have been published on the surgical treatment of this condition, especially in skeletally mature patients. With this study, we presented a retrospective case series of long-term surgical results for achondroplastic patients with severe thoracolumbar kyphosis. This study was conducted to evaluate the outcome of surgical treatment for thoracolumbar kyphosis in patients associated with achondroplasia presenting with paraparesis. Materials and Methods: Three patients with achondroplasia who developed neurologic deficits due to severe thoracolumbar kyphosis and underwent surgical treatment were evaluated (mean age 22.3 years; mean follow-up 9.3 years). All patients were treated with posterior vertebral column resection (p-VCR) of hypoplastic apical vertebrae with a cage and segmental instrumentation. Neurologic outcomes (JOA scores), correction of kyphosis, and operative complications were assessed. Results: All patients had back pain, neurological deficits, and urinary disturbance before surgery. The average preoperative JOA score was 8.3/11 points, which was improved to 10.7/11 points at the final follow-up (mean recovery rate 83%). All patients obtained neurologic improvement after surgery. The mean preoperative kyphotic angle was 117° (range 103°-126°). The postoperative angles averaged 37° (range 14°-57°), resulting in a mean correction rate of 67%. All patients had postoperative complications such as rod breakage and/or surgical site infection. Conclusions: The long-term results of p-VCR were acceptable for treating thoracolumbar kyphosis in patients with achondroplasia. To perform this p-VCR safely, spinal navigation and neuromonitoring are inevitable when resecting non anatomical fused vertebrae and ensuring correct pedicle screw insertion. However, surgical complications such as rod breakage and surgical site infection may occur at a high rate, making informed consent very important when surgery is indicated.

Comparison of Navigated Expandable Vertebral Cage with Conventional Expandable Vertebral Cage for Minimally Invasive Lumbar/Thoracolumbar Corpectomy.

Background and Objectives: The thoracolumbar burst fracture is one of the most common spinal injuries. If the patient has severe symptoms, corpectomy is indicated. Currently, minimally invasive corpectomy with a navigated expandable vertebral cage is available thanks to spinal surgical technology. The aim of this study is to retrospectively compare clinical and radiographic outcomes of conventional and navigational minimally invasive corpectomy techniques. Materials and Methods: We retrospectively evaluated 21 patients who underwent thoracolumbar minimally invasive corpectomy between October 2016 and January 2021. Eleven patients had a navigated expandable cage (group N) and 10 patients had a conventional expandable cage (group C). Mean follow-up period was 31.9 months for group N and 34.7 months for group C, ranging from 12 to 42 months in both groups. Clinical and radiographic outcomes are assessed using values including visual analogue scale (VAS) for back pain and Oswestry disability index (ODI). This data was collected preoperatively and at 6, 12, and 24 months postoperatively. Results: Surgical time and intraoperative blood loss of both groups were not significantly different (234 min vs. 267 min, 656 mL vs. 786 mL). Changes in VAS and ODI were similar in both groups. However, lateral cage mal-position ratio in group N was lower than that of group C (relative risk 1.64, Odds ratio 4.5) and postoperative cage sinking was significantly lower in group N (p = 0.033). Conclusions: Clinical outcomes are not significantly different, but radiographic outcomes of lateral cage mal-position and postoperative cage sinking were significantly lower in the navigation group.

Three-Dimensional Analysis of the Ideal Entry Point for Sacral Alar Iliac Screws.

STUDY DESIGN: This is a virtual three-dimensional (3D) imaging study examining computed tomography (CT) data to investigate instrumentation placement. PURPOSE: In this study, we aim to clarify the ideal entry point and trajectory of the sacral alar iliac (SAI) screw in relationship to the dorsal foramen at S1 and the respective nerve root. OVERVIEW OF LITERATURE: To the best of our knowledge, there is yet no detailed 3D imaging study on the ideal entry point of the SAI screw. Despite the evidence suggesting that the dorsal foramen at S1 is a landmark on the sacrum, the S1 nerve root disruption is a general concern during the insertion of SAI screws. No other study has been published examining the nerve root location at the S1and SAI screw insertions. METHODS: Preoperative CT data from 26 patients pertaining to adult spinal deformities were investigated in this study. We applied a 3D image processing method for a detailed investigation. Virtual cylinders were used to mimic SAI screws. These were placed to penetrate the sacral iliac joint without violating the other cortex. We then assessed the trajectory of the longest SAI screw and the ideal entry point of SAI using a color mapping method on the surface of the sacrum. We measured the location of the nerve root at S1 in relation to the foramen at S1 and the sacral surface. RESULTS: As per the results of our color mapping, it was determined that areas that received high scores are located medially and caudally to the dorsal foramen of S1. The mean angle between a horizontal line and a line connecting the medial edge of the foramen and nerve root at S1 was 93.5°. The mean distances from the dorsal medial edge of the foramen and sacral surface to S1 nerve root were 21.8 mm and 13.9 mm, respectively. CONCLUSIONS: The ideal entry point of the SAI screw is located medially and caudally to the S1 dorsal foramen based on 3D digital mapping. It is also shown that this entry point spares the S1 nerve root from possible iatrogenic injuries.

Comparison of Simultaneous Single-Position Oblique Lumbar Interbody Fusion and Percutaneous Pedicle Screw Fixation with Posterior Lumbar Interbody Fusion Using O-arm Navigated Technique for Lumbar Degenerative Diseases.

Minimally invasive posterior or transforaminal lumbar interbody fusion (MI-PLIF/TLIF) are widely accepted procedures for lumbar instability due to degenerative or traumatic diseases. Oblique lateral interbody fusion (OLIF) is currently receiving considerable attention because of the reductions in damage to the back muscles and neural tissue. The aim of this study was to compare clinical and radiographic outcomes of simultaneous single-position OLIF and percutaneous pedicle screw (PPS) fixation with MI-PLIF/TLIF. This retrospective comparative study included 98 patients, comprising 63 patients with single-position OLIF (Group SO) and 35 patients with MI-PLIF/TLIF (Group P/T). Cases with more than 1 year of follow-up were included in this study. Mean follow-up was 32.9 ± 7.0 months for Group SO and 33.7 ± 7.5 months for Group P/T. Clinical and radiological evaluations were performed. Comparing Group SO to Group P/T, surgical time and blood loss were 118 versus 172 min (p < 0.01) and 139 versus 374 mL (p < 0.01), respectively. Cage height, change in disk height, and postoperative foraminal height were significantly higher in Group SO than in Group P/T. The fusion rate was 96.8% in Group SO, similar to the 94.2% in Group P/T (p = 0.985). The complication rate was 6.3% in Group SO and 14.1% in Group P/T (p = 0.191). Simultaneous single position O-arm-navigated OLIF reduces the surgical time, blood loss, and time to ambulation after surgery. Good indirect decompression can be achieved with this method.

Assessment of the Concordance Rate between Intraoperative Pathological Diagnosis and the Final Pathological Diagnosis of Spinal Cord Tumors.

The intraoperative pathological diagnosis (IPD) plays an important role in determining the optimal surgical treatment for spinal cord tumors. The final pathological diagnosis (FPD) is sometimes different from the IPD. Here, we sought to identify the accuracy of the IPD of spinal cord tumors compared to the FPD. We retrospec-tively analyzed the cases of 108 patients with spinal cord tumors treated surgically in our institute; the IPD, FPD, mismatched cases, and concordance rate between the IPD and FPD were investigated. Five cases involved a mismatch between the IPD and FPD. The overall concordance rate was 95.4%, with 90.9% for extra-dural lesions, 98.5% for intradural extramedullary lesions, 84.2% for intramedullary lesions, and 100% for dumbbell-type tumors. The concordance rate of intramedullary lesions tended to be lower than that of other lesions (p = 0.096). A lower concordance rate was revealed for intramedullary lesions compared to the other lesions. Despite the IPD clearly remaining a valuable tool during operative procedures, surgeons should recog-nize the limitations of IPDs and make comprehensive decisions about surgical treatments.

Robot-assisted intrathoracic procedure for dumbbell tumour in the prone position.

A 24-year-old man presented with a dumbbell-shaped right posterior mediastinal mass. The patient was placed in the prone position following general anaesthesia and intubation. After laminectomy and dissection of the dorsal part of the tumour using a posterior approach were performed, the tumour was completely resected using a robotic approach in the thoracic cavity without repositioning. This is the first report of robotic resection for posterior mediastinal tumour in the prone position as well as a novel combined posterior approach and robotic resection for dumbbell tumours.

Quantification of patellar tendon reflex using portable mechanomyography and electromyography devices.

Deep tendon reflexes are one of the main components of the clinical nervous system examinations. These assessments are inexpensive and quick. However, evaluation can be subjective and qualitative. This study aimed to objectively evaluate hyperreflexia of the patellar tendon reflex using portable mechanomyography (MMG) and electromyography (EMG) devices. This study included 10 preoperative patients (20 legs) who had a pathology that could cause bilateral patellar tendon hyperreflexia and 12 healthy volunteers (24 legs) with no prior history of neurological disorders. We attached MMG/EMG sensors onto the quadriceps and tapped the patellar tendon with maximal and constant force. Our results showed a significantly high amplitude of the root mean square (RMS) and low frequency of the mean power frequency (MPF) in the rectus femoris, vastus medialis, and vastus lateralis muscles in both EMG and MMG with both maximal and constant force. Especially in the patients with cervical and thoracic myelopathy, the receiver operating characteristic (ROC) curve for diagnosing hyperreflexia of the patellar tendon showed a moderate to very high area under the curve for all EMG-RMS, EMG-MPF, MMG-RMS, and MMG-MPF values. The use of EMG and MMG for objectively quantifying the patellar tendon reflex is simple and desirable for future clinical applications and could help diagnose neurological disorders.

Short-term outcomes of mirogabalin in patients with peripheral neuropathic pain: a retrospective study.

BACKGROUND: Mirogabalin, which is approved for the treatment of peripheral neuropathic pain in Japan, is a ligand for the α2δ subunit of voltage-gated calcium channels. Both pregabalin and mirogabalin act as nonselective ligands at the α2δ-1 and α2δ-2 subunits. Mirogabalin has a unique binding profile and long duration of action. Pregabalin has been reported to produce intolerable adverse effects in some patients. This study investigated outcomes associated with mirogabalin administration in patients with peripheral neuropathic pain who ceased treatment with pregabalin. METHODS: We retrospectively assessed peripheral neuropathic pain using the neuropathic pain screening questionnaire (NeP score) in 187 patients (58 men, 129 women) who were treated with mirogabalin. All patients had switched from pregabalin to mirogabalin due to lack of efficacy or adverse events. Differences in the treatment course (i.e., numeric rating scale (NRS) scores) were compared using one-way analysis of variance with Bonferroni post hoc tests. RESULTS: The mean age of the patients was 72.3 years (range, 30-94 years), and the mean duration of disease was 37 months (range, 3-252 months). After treatment with mirogabalin for 1 week, NRS scores significantly decreased compared with baseline and continued to decrease over time. After 8 weeks, NRS scores improved by ≥ 30% from baseline in 113 patients (69.3%). Twenty-four patients (12.8%) stopped mirogabalin treatment due to adverse events. Somnolence (26.7%), dizziness (12.3%), edema (5.9%), and weight gain (0.5%) were noted as adverse events of mirogabalin. CONCLUSIONS: The results of this investigation indicate that mirogabalin is safe and effective for reducing peripheral neuropathic pain.

Minimally Invasive Surgery for Unstable Pelvic Ring Fractures: Transiliac Rod and Screw Fixation.

Pelvic fractures occur with high-energy trauma, and the patient's clinical status is unstable. Although a number of surgical methods for unstable pelvic fractures are available, none can achieve strong fixation with minimal invasiveness. We describe a surgical transiliac rod and screw fixation (TIF) procedure that provides minimally invasive fixation using a spinal implant for unstable pelvic ring fractures, and we retrospectively analyzed the procedure's outcomes in 27 patients with type B or C1 fractures (based on the AO/ATO classification system). Small skin incisions are made above the posterior superior iliac spines on both sides. The ilium is partially resected, and two iliac screws are inserted on each side. The spinous process of the sacral spine is then shaved, and the iliac screws are connected to 2 rods, one placed caudal to the other. Corrective manipulation is performed at the fracture site, and the rods are connected with connectors. Favorable fracture reduction, defined as a rating of 'excellent' or 'good,' was achieved in 77.8% of the patients. Transiliac rod and screw fixation (TIF) will be a useful therapeutic option for unstable pelvic ring fractures.

Multipotent Neurotrophic Effects of Hepatocyte Growth Factor in Spinal Cord Injury.

Spinal cord injury (SCI) results in neural tissue loss and so far untreatable functional impairment. In addition, at the initial injury site, inflammation induces secondary damage, and glial scar formation occurs to limit inflammation-mediated tissue damage. Consequently, it obstructs neural regeneration. Many studies have been conducted in the field of SCI; however, no satisfactory treatment has been established to date. Hepatocyte growth factor (HGF) is one of the neurotrophic growth factors and has been listed as a candidate medicine for SCI treatment. The highlighted effects of HGF on neural regeneration are associated with its anti-inflammatory and anti-fibrotic activities. Moreover, HGF exerts positive effects on transplanted stem cell differentiation into neurons. This paper reviews the mechanisms underlying the therapeutic effects of HGF in SCI recovery, and introduces recent advances in the clinical applications of HGF therapy.

Minimally Invasive Percutaneous Spinopelvic Fixation for Unstable Pelvic Ring Fracture Performed With the Patient in a Lateral Position.

Spinopelvic fixation provides a strong fixation for unstable pelvic ring fractures. However, the technique is usually performed with the patient in the prone position, with the applied weight on the anterior superior iliac crests aggravating fracture displacement. We developed a novel approach for minimally invasive percutaneous spinopelvic fixation that is performed with the patient in a lateral (side lying) position. We describe the application of our technique for the treatment of a bilateral pelvic ring and acetabulum fracture in a 79-year-old woman injured in a traffic accident. Initial posterior fixation was performed with the patient in the left-side lying position, using bilateral pedicle screws at L3 and L4 and a left sacral-alar iliac screw and 2 right iliac screws inserted under navigation. The lateral and cranial displacement of the right pelvic ring was reduced percutaneously. One week after this initial surgery, we proceeded with an open anterior reduction and internal fixation of the left pelvic ring and acetabulum fracture. The postoperative course was uneventful and clinical outcomes were satisfactory. Reduction of a pelvic ring fracture in a lateral position, with subsequent spinopelvic fixation, is a reasonable option for the treatment of an unstable pelvic ring fracture.

Early response assessment of re-ossification after palliative conventional radiotherapy for vertebral bone metastases.

BACKGROUND: To evaluate the therapeutic outcomes in patients with bone metastases receiving radiotherapy (RT), it is important to use objective radiological response criteria. The aim of this study was to investigate the changes in pain and re-ossification after RT for painful vertebral bone metastases without paralysis by malignant spinal cord compression. METHODS: The participants included 55 patients who received RT for painful vertebral bone metastases without paralysis in our institution between 2012 and 2016. Bone modifying agents (BMAs) were administered in all patients. Follow-up assessments were done just before the start of RT and at 1, 2, 3, 4, and 6 months after RT. Radiological responses of irradiated vertebrae by RT were assessed by computed tomography (CT) using MD Anderson response classification criteria (MDA criteria) and the pain response was assessed by Numeric Rating Scale (NRS). Response was classified as complete response (CR), partial response (PR), progressive disease (PD), and stable disease (SD). RESULTS: The rates of CR were 2%, 7%, 20%, 30%, and 56% at 1, 2, 3, 4, and 6 months, respectively. The rates of CR or PR were 15%, 49%, 77%, 91%, and 91% at 1, 2, 3, 4, and 6 months, respectively. The rates of CR or PR were significantly higher in patients with breast cancer than in patients with lung cancer (p = 0.043). At one month, there was an association between the NRS and radiological response assessed by MDA criteria. There was a significant trend that, with a better response, there were more patients without pain (p = 0.021). CONCLUSIONS: Under BMAs administration, successful RT for vertebral bone metastases decreased pain and caused re-ossification. The MD Anderson criteria could be useful for assessment of radiological responses of irradiated vertebrae.

Drug dependence in patients with chronic pain: A retrospective study.

Drug dependence, which can exist concurrently with chronic pain, is seen as one of the major causes of rapidly increasing medical expenses. However, drug dependence in patients with chronic pain has not been evaluated. The aim of this study was to identify the risk factors for drug dependence in patients with chronic noncancer pain.This retrospective study included 151 patients with chronic noncancer pain (43 males, 108 females; mean age, 72 years). Low back pain (LBP) occurred in 96 patients, whereas 22 had shoulder pain, 8 had hip pain, and 77 had knee pain. Patients were divided into drug dependence and nondrug dependence groups based on the Severity of Dependence Scale (SDS) scores. Patients with SDS scores ≥5 and <5 were classified into drug dependence and nondrug dependence groups, respectively. All patients completed self-report questionnaires. Factors that predict drug dependence were identified by performing univariate and multivariate analyses.Sixty (40%) of the 151 patients met the SDS criteria for drug dependence. Significant differences were found between patients with and without drug dependence for the LBP, hip pain, number of medications, and for the Numerical Rating Scale, Pain Disability Assessment Scale (PDAS), Hospital Anxiety and Depression Scale, and Pain Catastrophizing Scale (PCS) scores. Multiple regression analysis identified LBP, hip pain, PCS, and PDAS scores as factors related to drug dependence in patients with chronic noncancer pain.Drug dependence tends to differ in patients based on the location of their chronic pain. Pain catastrophizing and disability indicated a greater tendency for drug dependence. Thus, PCS and PDAS scores are useful screening tools for predicting drug dependence in patients with chronic pain.

An evaluation of anesthetic fade in motor evoked potential monitoring in spinal deformity surgeries.

BACKGROUND: Intraoperative neuromonitoring using motor evoked potentials (MEP) satisfactorily detects motor tract integrity changes during spinal surgery. However, monitoring is affected by "anesthetic fade," in which the stimulation threshold increases because the waveform amplitude decreases with the accumulation of propofol. Therefore, the purpose of this study was to clarify the effect of anesthetic fade on transcranial MEPs by investigating the time-dependent changes of amplitude during spinal deformity surgeries. METHODS: We retrospectively reviewed medical records of 142 spinal deformity patients (66 patients with idiopathic scoliosis, 28 with adult spinal deformities, 19 with neuromuscular scoliosis, 17 with syndromic scoliosis, and 12 with congenital scoliosis). The average age was 28 years (range, 5 to 81 years). MEPs were recorded bilaterally from the abductor digiti minimi (ADM) and abductor hallucis (AH) muscles during spinal deformity surgeries. The Wilcoxon signed-rank test was used to investigate the time-dependent changes of amplitude after propofol infusion to evaluate anesthetic fade effects. RESULTS: The average time to baseline from initial propofol infusion was 113 min (range, 45 to 182 min). In the ADM, the amplitude was 52% at 1 h after initial propofol infusion, 102% at 2 h, 105% at 3 h, 101% at 4 h, 86% at 5 h, and 81% at 6 h. Compared to the 2-h time point, MEP decreased significantly by 16% at 5 h (P < 0.0005) and by 21% at 6 h (P < 0.05). In the AH, the amplitude was 49% at 1 h after initial infusion of propofol, 102% at 2 h, 102% at 3 h, 92% at 4 h, 71% at 5 h, and 63% at 6 h. Compared to the 2-h time point, MEP decreased significantly by 10% at 4 h (P < 0.005), by 31% at 5 h (P < 0.0000005), and by 39% at 6 h (P < 0.05). CONCLUSIONS: MEP amplitude significantly decreased in the upper limbs at 5 and 6 h and in the lower limbs at 4, 5, and 6 h after the initial infusion of propofol, respectively. The influence of anesthetic fade could influence false positive MEPs during long spinal surgeries.

Venous Thromboembolism in Patients with Acute Thoracolumbar Spinal Cord Injury.

Venous thromboembolism (VTE) is a major complication in patients with acute spinal cord injury. There are few reports of VTE with acute thoracolumbar spinal cord injury (TLSCI). We assessed the incidence of VTE with acute TLSCI using color Doppler ultrasonography. We retrospectively assessed 75 patients with acute TLSCI (T1 to L1). All patients were surgically treated. VTE of the lower extremity and pelvis was assessed using color Doppler ultrasound regardless of whether symptoms were present. This retrospective study included patients who were assessed between 6 and 10 days (mean 8.1 days) after injury. VTE was detected in 27 of the 75 patients (35.7%) with or without paralysis. Of the 13 patients who had complete motor paralysis, 8 (62%) had VTE; of the 31 patients with incomplete motor paralysis, 10 (32%) had VTE, and of the 31 patients without motor paralysis, 9 (29%) had VTE. Among the patients with TLSCI, those with VTE had a significantly higher mean age than those without. The incidence of VTE in TLSCI patients is not related to the severity of paralysis in a Japanese population. The incidence appears to be related primarily to age.