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David G. Kline and Daniel H. Kim

Object. The purpose of this paper was to analyze outcomes in patients at the Louisiana State University Health Sciences Center (LSUHSC) who presented with contusion—stretch injuries to the axillary nerve. These injuries resulted from shoulder injury either with or without fracture/dislocation. Although recovery of deltoid function can occur spontaneously, this was not always the case.

Methods. Severe deficits persisting for several months led the patients to undergo surgery. Operative categories included isolated axillary palsy (56 procedures), combined axillary and suprascapular palsies (11 procedures), axillary and radial palsies (14 procedures), and axillary palsy with another deficit, usually infraclavicular plexus loss (20 procedures). Deltoid function was evaluated pre- and postoperatively by applying the LSUHSC grading system. An anterior infraclavicular approach was usually followed during surgery, but in three patients an additional posterior approach was used.

Axillary lesions usually began in the proximal portion of the posterior cord. Although several patients had distraction of the nerve, lesions in continuity were found in more than 90% of cases. Intraoperative nerve action potential (NAP) recordings were performed to determine the need for resection. Most repairs were made using grafts, although in three patients with relatively focal lesions suture was used.

When an NAP was recorded across the lesion and neurolysis was performed, recovery was judged to be a mean Grade 4 according to the LSUHSC in 30 cases. Recovery following suture repairs was a mean Grade 3.8, whereas recovery after 66 graft repairs was a mean Grade 3.7. In cases in which suprascapular palsies were associated with axillary injuries, the former recovered but the latter did not necessarily do so without surgery. If the radial nerve was also injured, recovery of the triceps and brachioradialis muscles and wrist extension was usually obtained, but it was far more difficult to reverse the loss of finger and thumb extension. Although few in number, complications did occur and they are important.

Conclusions. Operative exploration of axillary contusion—stretch lesions is worthwhile in carefully selected cases. If indicated by inspection and intraoperative electrical studies, nerve repair can lead to useful function.

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Daniel H. Kim and David G. Kline

✓ Seventy-eight traumatic neuropathies were seen in 94 patients with femoral nerve lesions; 54 of these were operated on because of persistent complete functional loss and/or pain. The most common mechanism of injury to the femoral nerve was iatrogenic due to inguinal herniorrhaphy, total hip replacement, intraabdominal vascular or gynecological operation, and, less commonly, appendectomy, lumbar sympathectomy, and laparoscopic procedures. Femoral nerve injuries also resulted from penetrating gunshot and stab wounds, laceration by glass, and stretch/contusive injuries associated with pelvic fractures. There were no signs of clinical or electrical recovery in 45 of 78 patients with traumatic nerve injuries. These and other partial injuries associated with pain were explored and evaluated by intraoperative nerve stimulation and recording of nerve action potentials (NAPs).

Despite complete loss of nerve function preoperatively, 13 patients had recordable NAPs and underwent neurolysis; each recovered function to at least a Grade 3 level. Twenty-seven patients had sural graft repairs performed with graft lengths varying from 2.5 to 14 cm. Most patients had some nerve regeneration and regained function to Grade 3 to 4 levels by 2 years postoperatively. Four of five patients with suture repairs recovered to Grade 3 or better within 2 years postoperatively. Despite a proximal pelvic level for most of these injuries and, as a result, lengthy graft repairs, recovery of some useful function was the rule rather than the exception. Tumors involved the femoral nerve in 16 patients and included eight neurofibromas, four schwannomas, one neurogenic sarcoma, two ganglion cysts, and one leiomyosarcoma. All tumors were treated surgically and most were removed successfully.

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Sung-Min Kim, T. Jesse Lim, Josemaria Paterno and Daniel H. Kim

Object. Facet screw fixation is the lowest profile lumbar stabilization method. In this study the immediate biomechanical stability provided by the two different types of fixation are compared: translaminar facet screw (TLFS) and transfacetopedicular screw (TFPS) placement after anterior lumbar interbody fusion (ALIF) using a femoral ring allograft. Both facet screw fixation types were also compared with the gold standard, transpedicular screw and rod (TSR) fixation.

Methods. Twenty-four human lumbosacral spines were tested in the following sequence: intact state, after discectomy, after ALIF, and after TLFS, TFPS, or TSR fixation. Intervertebral motions were measured by a video-based motion capture system. The range of motion (ROM) and neutral zone (NZ) were compared for each loading to a maximum of 7.5 Nm.

The ROMs for stand-alone ALIFs were less than but similar to those of the intact spine, but NZs were slightly increased in all modes. The ROMs for both TLFS and TFPS fixation were significantly decreased from those of the intact spine in all modes and those of the stand-alone ALIF in flexion and extension. The TLFS and TFPS fixations significantly reduced NZs to below that of the intact spine in all modes. Compared with NZs for ALIF, both types of fixation revealed significantly lower values, except for TLFS placement in lateral bending and TFPS fixation in lateral bending and rotation. There were no significant differences between TLFS and TFPS fixation. There were also no significant differences among both TLFS and TFPS and TSR fixations, except that TFPS was inferior to TSR in lateral bending.

Conclusions. Stand-alone ALIF may not provide sufficient stability. Both facet fixations produced significant additional stability and both are comparable to TSR fixation. Although TFPS fixation revealed a slightly inferior result, TFPSs can be placed percutaneously with the assistance of fluoroscopic guidance and it makes the posterior facet fixation minimally invasive. Therefore, the TFPS fixation can be considered as a good alternative to TLFS fixation.

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Hoang Le, Issada Thongtrangan and Daniel H. Kim

Early attempts at spinal arthroplasty in the 1950s yielded limited success. A revival of this procedure occurred in the 1980s and became a realistic treatment option in the 1990s. Both lumbar and cervical arthroplasties have been introduced in the US since 2000 for randomized, prospective studies in accordance with the Food and Drug Administration (FDA) investigational device exemption provisions. In June 2004 the first lumbar arthroplasty device was approved by the FDA for use in the US. It is likely that cervical arthroplasty will soon follow and may be available for widespread use as early as 2006. In this paper the authors review the historical development of cervical arthroplasty.

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Issada Thongtrangan, Raju S. V. Balabhadra and Daniel H. Kim

Although successfully used, long strut grafts are vulnerable to dislodgment, displacement, fracture, and nonunion, which can require revision surgery; thus, meticulous preparation of the vertebral endplate along with exact sizing and harvesting of the bone graft with plating are essential for successful outcomes. Biomechanical data and previous clinical studies support the addition of posterior fusion and fixation following multilevel (more than two-level) corpectomy. The additional posterior instrumentation moves the instantaneous axis of rotation posteriorly, thus approximating its normal location in the posterior vertebral body (VB). Biomechanically, this protects the graft from excessive loads while in extension and explains the clinical success of circumferential instrumentation for long-segment corpectomy reconstructions. If strut fracture occurs with minimal displacement and the graft position is still satisfactory, application of a halo vest and judicious observation are recommended. Significant displacement, kyphosis, or loss of contact of the graft and VB require revision surgery. In patients requiring revision surgery for nonunion, placement of fibular autograft or allograft with use of bone morphogenetic protein is likely to be beneficial. If questions remain regarding bone quality or construct stability, the supplemental use of posterior stabilization is recommended. Various surgical approaches have been advocated for treatment of symptomatic anterior cervical pseudarthroses or nonunion. It remains controversial as to whether the anterior or posterior approach is best. Adequate understanding of the graft and implant biomechanics are essential for a successful outcome.

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Neurofibromatosis-associated nerve sheath tumors

Case report and review of the literature

Judith A. Murovic, Daniel H. Kim and David G. Kline

In this paper the authors describe a patient with neurofibromatosis Type 1 (NF1) who presented with sequelae of this disease. They also review the current literature on NF1 and NF2 published between 2001 and 2005.

The method used to obtain information for the case report consisted of a family member interview and a review of the patient's chart. For the literature review the authors used the search engine Ovid Medline to identify papers published on the topic between 2001 and 2005. Neurofibromatosis Type 1 appears in approximately one in 2500 to 4000 births, is caused by a defect on 17q11.2, and results in neurofibromin inactivation. The authors reviewed the current literature with regard to the following aspects of this disease: 1) diagnostic criteria for NF1; 2) criteria for other NF1-associated manifestations; 3) malignant peripheral nerve sheath tumors (PNSTs); 4) the examination protocol for a patient with an NF1-related NST; 5) imaging findings in patients with NF1; 6) other diagnostic studies; 7) surgical and adjuvant treatment for NSTs and malignant PNSTs; and 8) hormone receptors in NF1-related tumors. Pertinent illustrations are included.

Neurofibromatosis Type 2 occurs much less frequently than NF1, that is, in one in 33,000 births. Mutations in NF2 occur on 22q12 and result in inactivation of the tumor suppressor merlin. The following data on this disease are presented: 1) diagnostic criteria for NF2; 2) criteria for other NF2 manifestations; 3) malignant PNSTs in patients with NF2; 4) examination protocol for the patient with NF2 who has an NST; and 5) imaging findings in patients with NF2. Relevant illustrations are included.

It is important that neurosurgeons be aware of the sequelae of NF1 and NF2, because they may be called on to treat these conditions.

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Stephen I. Ryu, Daniel H. Kim and Steven D. Chang

Object

The optimal treatment for intramedullary spinal tumors is controversial, because both resection and conventional radiation therapy are associated with potential morbidity. Stereotactic radiosurgery can theoretically deliver highly conformal, high-dose radiation to surgically untreatable lesions while simultaneously mitigating radiation exposure to large portions of the spinal cord. The purpose of this study was to evaluate the authors' initial experience with frameless stereotactic radiosurgery for intramedullary spinal tumors.

Methods

Between 1998 and 2003, 10 intramedullary spinal tumors were treated with stereotactic radiosurgery at the authors' institution. Seven hemangioblastomas and three ependymomas were treated in four men and three women. These patients either had recurrent tumors, had undergone several previous surgeries, had medical contraindications to surgery, or had declined open resection. Conformal treatment planning delivered a prescribed dose of 1800 to 2500 cGy (mean 2100 cGy) to the lesions in one to three stages. No significant treatment-related complications have been recorded. The mean radiographic and clinical follow-up duration was 12 months (range 1–24 months). One ependymoma and two hemangioblastomas were smaller on follow-up neuroimaging. The remaining tumors were stable at the time of follow-up imaging.

Conclusions

Stereotactic radiosurgery for intramedullary spinal tumors is feasible and safe in selected cases and may prove to be another therapeutic option for these challenging lesions.

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Daniel K. Fahim, Sang Don Kim, Dosang Cho, Sangkook Lee and Daniel H. Kim

Object

The thoracolumbar junction is frequently accessed through an anterolateral approach with the incision and muscle dissection extending from the lower thoracic region to the lateral border of the rectus abdominis muscle. This approach is frequently associated with the subsequent development of an unsightly and uncomfortable relaxation of the ipsilateral abdominal wall, or flank bulge, caused by denervation injury to the intercostal nerves. However, the etiology of this complication is not widely recognized by spine surgeons. The object of this study was to better define the relevant anatomy and innervation of the anterolateral abdominal wall musculature.

Methods

The authors performed 32 cadaveric dissections and 6 intraoperative electromyography (EMG) evaluations.

Results

The cadaveric dissection studies and intraoperative EMG evaluations provided detailed anatomy of the anterolateral abdominal wall and its innervation. Cadaveric dissections revealed that the most significant intercostal nerve contributions to the anterolateral abdominal wall arise from T11 and T12. Electrophysiological confirmation of these findings was accomplished through intraoperative stimulation in 6 patients undergoing anterolateral retroperitoneal approaches to the thoracolumbar junction. The authors confirmed T11 and T12 innervation of the anterolateral abdominal wall musculature by direct intraoperative EMG recording in all 6 patients.

Conclusions

The authors classified the 3 potential zones of injury that can be affected during an anterolateral approach to the thoracolumbar junction. Modifications to the operative technique are suggested to avoid the complication of flank bulge. The most significant intercostal nerve contributions to the anterolateral abdominal wall arise from T11 and T12.

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Sung-Min Kim, T. Jesse Lim, Josemaria Paterno, Jon Park and Daniel H. Kim

Object. The stability of lateral lumbar interbody graft—augmented fusion and supplementary lateral plate fixation in human cadavers has not been determined. The purpose of this study was to investigate the immediate biomechanical stabilities of the following: 1) femoral ring allograft (FRA)—augmented anterior lumbar interbody fusion (ALIF) after left lateral discectomy combined with additional lateral MACS HMA plate and screw fixation; and 2) ALIF combined with posterior transpedicular fixation after anterior discectomy.

Methods. Sixteen human lumbosacral spines were loaded with six modes of motion. The intervertebral motion was measured using a video-based motion-capturing system. The range of motion (ROM) and the neutral zone (NZ) in each loading mode were compared with a maximum of 7.5 Nm.

The ROM values for both stand-alone ALIF approaches were similar to those of the intact spine, whereas NZ measurements were higher in most loading modes. No significant intergroup differences were found. The ROM and NZ values for lateral fixation in all modes were significantly lower than those of intact spine, except when NZ was measured in lateral bending. All ROM and NZ values for transpedicular fixation were significantly lower than those for stand-alone anterior ALIF. Transpedicular fixation conferred better stabilization than lateral fixation in flexion, extension, and lateral bending modes.

Conclusions. Neither approach to stand-alone FRA-augmented ALIF provided sufficient stabilization, but supplementary instrumentation conferred significant stabilization. The MACS HMA plate and screw fixation system, although inferior to posterior transpedicular fixation, provided adequate stability compared with the intact spine and can serve as a sound alternative to supplementary spinal stabilization.

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Daniel H. Kim, Judith A. Murovic, Yong-Yeon Kim and David G. Kline

Object

The authors report data in 45 surgically treated posterior interosseous nerve (PIN) entrapments or injuries.

Methods

Forty-five PIN entrapments or injuries were managed surgically between 1967 and 2004 at Louisiana State University Health Sciences Center (LSUHSC) or Stanford University Medical Center. Patient charts were reviewed retrospectively. The LSUHSC grading system was used to assess PIN-innervated muscle function.

Injuries were caused by nontraumatic (21 PIN entrapments and four tumors) and traumatic (nine lacerations, eight fractures, and three contusions) mechanisms. Presentations included weakness in the extensor carpi ulnaris muscle, causing compromised wrist extension and radial drift; extensor digitorum, indicis, and digiti minimi muscles with paretic finger extension; extensor pollicis brevis and longus muscles with weak thumb extension; and abductor pollicis longus muscle with rare decreased thumb abduction due to substitutions of the median nerve–innervated abductor pollicis brevis muscle and, at 90°, the extensor pollicis brevis and longus muscles. Preoperative evaluations consisted of electromyography and nerve conduction studies, elbow and forearm plain x-ray films, and magnetic resonance imaging for tumor detection.

At surgery, in continuity lesions were found in 21 entrapments and three fracture-related and three contusion injuries; all transmitted nerve action potentials (NAPs) and were treated with neurolysis. Five fracture-related PIN injuries, one of which was a lacerating injury, were in continuity and transmitted no NAPs; graft repairs were performed in all of these cases. Among nine lacerations, three PINs appeared in continuity, although intraoperative NAPs were absent. Two of these nerves were treated with secondary end-to-end suture anastomosis repair and one with secondary graft repair. There were six transected lacerations: three were treated with primary suture anastomosis repair, two with secondary suture anastomosis, and one with graft repair. Four tumors involving the PIN were resected. Most muscles innervated by 45 PINs had LSUHSC Grade 3 or better functional outcomes.

Conclusions

Forty-five PIN entrapments or injuries responded well to PIN release and/or repair.