Give neurosurgery a place to stand. The 2001 presidential address.

In his 2001 Presidential Address to the American Association of Neurological Surgeons, Dr. Dunsker calls on all neurosurgeons to become active participants in the ongoing debates over healthcare. He reviews some history of the debates and points out that regulation of healthcare has been left to bureaucrats-both government and private-with physicians, who have intimate knowledge of the field, being excluded. Dr. Dunsker encourages neurosurgeons to volunteer in local, state, and federal medical societies and to join forces with other physicians to gain leverage in the healthcare debate. In this manner it is hoped that better ways of delivering the best healthcare to patients can be accomplished.

Use of calcitonin for the treatment of an odontoid fracture. Case report.

The authors report on the efficacy of nonsurgical treatment of an older patient with a fractured odontoid process. The patient, an 85-year-old woman, had multiple medical problems that put her at an increased surgery-related risk. Therefore, an alternative approach was elected, including immobilization with a Philadelphia collar and the provision of calcitonin nasal spray. Bone union and clinical recovery were achieved within 8 weeks of initiating the nasal calcitonin therapy (12 weeks postinjury). Considering the patient's age, comorbidities, and the severity of the fracture, the recovery period was unusually short. The authors believe that calcitonin played a pivotal role in the healing process of the fractured odontoid bone. There is no question that the fusion in this patient could be unrelated to the medical therapy. This description of one patient, as well as the lack of a large randomized study, precludes any scientific conclusions. Nevertheless, the authors believe that the development of a successful fusion in this high-risk patient should be reported as an observation that merits confirmation and study. The authors also discuss the physiological effects of calcitonin and the research and clinical experience with this hormone in different conditions affecting bone.

Port-access first-rib resection.

We have developed a thoracoscopic first rib resection technique for treatment of thoracic outlet syndrome (TOS), employing new instruments designed for endoscopic surgery. A 49-year-old man with Paget-Schroetter syndrome was treated bilaterally, and a 25-year-old woman with neurologic symptoms was treated on the right side by thoracoscopic approach via three ports. Harmonic scalpel, endoscopic elevators, rongeurs, and an endoscopic drill were used. In two patients, approximately 80% of the first rib overlying the subclavian vessels and brachial plexus was successfully removed by this technique. We conclude that port-access first-rib resection is feasible and reproducible using the new instruments described.

Bilateral vocal cord paralysis following anterior cervical discectomy and fusion. Case report.

The authors report a rare case of bilateral vocal cord paralysis following anterior cervical discectomy and fusion (ACD/F) in a patient who had a preexisting, clinically silent, and unrecognized unilateral vocal cord paralysis from a remote cardiac surgical procedure. The patient, a 41-year-old woman who developed acute respiratory stridor and respiratory insufficiency at the time of extubation after undergoing a C6-7 ACD/F, required emergency reintubation and ventilation. Otolaryngological evaluation revealed bilateral vocal cord paralysis with one vocal cord showing evidence of acute paralysis and the other showing evidence of chronic paralysis. She eventually required a permanent tracheotomy. The patient had undergone previous cardiac surgical procedures to correct Fallot's tetralogy as a neonate and as a child. At those times, there were no recognized symptoms of transient or permanent vocal cord dysfunction. This case emphasizes the importance of identifying patients with preexisting unilateral vocal cord paralysis before performing neurosurgical procedures such as ACD/F, which can place the only functioning vocal cord at risk for paralysis. Guidelines for identifying patients with preexisting unilateral vocal cord paralysis and for modifying the surgical procedure for ACD/F to prevent the catastrophic complication of bilateral vocal cord paralysis are discussed.

Lymphoma of the lumbar nerve root: case report.

BACKGROUND AND IMPORTANCE: Lymphoma deposits in the spine are typically extradural. However, we report the case of a 38-year-old man who had a peripheral T-cell lymphoma with both intra- and extradural involvement. CLINICAL PRESENTATION: The patient presented with a 3-month history of right hip and thigh pain. Computed tomography and magnetic resonance imaging revealed features indistinguishable from those of a benign neurofibroma, except for a small area of T2-weighted signal abnormality in the third lumbar vertebral body. INTERVENTION: A solitary lesion of the right third lumbar root with normal surrounding bone and soft tissue was excised at surgery. At immunohistopathological evaluation, a diagnosis was made of peripheral lymphoma. Postoperative evaluation did not reveal lymphoma in the cerebrospinal fluid, abdomen, chest, blood, or bone marrow. This case illustrates that lymphomas can grow in patterns indistinguishable from a tumor of a nerve root. Therefore, other treatment modalities would have been considered had the diagnosis of lymphoma been made preoperatively. CONCLUSION: Involvement of a solitary nerve root by lymphoma, although rare, should be suspected in all cases of nerve root neurofibroma, and magnetic resonance imaging should be performed. Even minor signal abnormalities in adjoining vertebrae signal the possibility of malignancy. Percutaneous biopsy of suspicious bony lesions and systemic evaluation can demonstrate other sites of involvement, enabling the confirmation of the diagnosis and appropriate treatment without recourse to surgery.

Innervation of the spinal dura. Myth or reality?

STUDY DESIGN: Cranial and spinal dura from nine Sprague Dawley male rats were examined immunocytochemically for the presence of nerve fibers and mast cells and for innervation. The posterior longitudinal ligament and peridural membrane were also examined for these elements. OBJECTIVE: To examine the pattern of sensory innervation and the presence of mast cells in rat spinal dura. SUMMARY OF BACKGROUND DATA: The cranial dura is richly innervated and has a robust population of mast cells, which have been implicated in the pathogenesis of vascular headache. Moskowitz's explanation for vascular headache focused on the dura mater and neurogenic inflammation. Essential to his model are dural trigeminovascular fibers and mast cells. Previous studies provide contradictory and inconclusive results regarding spinal dural innervation. METHODS: Immunocytochemical techniques using antibodies to calcitonin gene-related peptide and substance P were used to identify sensory nerve fibers and antibodies to serotonin were used to identify mast cells. Specimens dissected included dura of the cranial vault in continuity with the dorsal cervical dura, dura of the skull base in continuity with the ventral cervical dura, lumbar dura, and posterior longitudinal ligament from the cervical and lumbar regions. RESULTS: A rich neural network and an abundant mast cell population were identified in the supratentorial and infratentorial cranial dura, both dorsally and ventrally. A paucity of nerve fibers and mast cells was observed in the cervical and lumbar dura; in contrast, these elements were prominent in the posterior longitudinal ligament and peridural membrane. CONCLUSIONS: Spinal dura does not have a rich innervation of calcitonin gene-related peptide- and substance P-positive nerve fibers or a robust population of mast cells. The spinal dura may serve as a protective covering. Unlike the cranial dura, it may not be implicated in the pathogenesis of pain. Additional studies on primate and human spinal dura are warranted to corroborate findings that the spinal dura may be relatively insensitive.

Chiari I malformation: classification and management.

Considerable debate exists about which surgical options are best for the management of the Chiari I malformation. We present a classification system for the Chiari I malformation that improves the prediction of outcome and guides the selection of surgical treatment. Twenty-seven adult patients with Chiari I malformations were grouped on the basis of the presence of signs and symptoms of brain stem compression, syringomyelia, or both. To objectively assess changes in clinical status postoperatively, a scale was developed to quantify the signs and symptoms, which were statistically analyzed by the paired t test. Five patients were asymptomatic and underwent no treatment. Ten patients had symptoms of brain stem compression without associated syringomyelia and underwent brain stem decompression, including anterior decompression in one patient with basilar invagination; all 10 patients had significant improvement at 4-year mean follow-up visits (P < 0.0001). In 12 patients with syringomyelia, 5 were symptomatic from syringomyelia only, 6 were symptomatic from both brain stem compression and syringomyelia, and 1 was symptomatic from brain stem compression only. The median length of symptoms before presentation was longer for patients with syringomyelia than for patients without (2 yr versus 9 mo; P < 0.025); the mean follow-up was 4 years. Surgical procedures included posterior brain stem decompression in 12 patients, plugging of the obex in 7, and placement of syringosubarachnoid shunts in 7, a syringopleural shunt in 1, and fourth ventricular stents in 2. In the 12 patients with syringomyelia, symptoms from brain stem compression dramatically improved with surgical decompression (P < 0.025), whereas symptoms from syringomyelia less dramatically improved or stabilized. The slight improvement or stabilization of syrinx symptoms represents a successful result, given the documented progressive nature of syringomyelia in this group. We conclude that surgical treatment for the Chiari I malformation can stabilize or slightly improve the symptoms attributed to syringomyelia and dramatically relieve the symptoms of brain stem compression. Furthermore, early diagnosis and treatment are critical in obtaining the best outcome for the patient.

Repair of spinal dural defects with vicryl (polyglactin 910) mesh.

This study examined and compared the effectiveness of woven vicryl (polyglactin 910) mesh and lyophilized cadaver dura (Lyodura) for the repair of spinal dural defects. A woven vicryl mesh was used to repair spinal dural defects in 16 mongrel dogs. As an internal control, all animals had a separate dural incision that was closed with 9-0 vicryl suture. Animals were killed, and results were evaluated at 4, 8, 12, and 24 weeks. The repair of dural defects was achieved in all animals, and there were no cases of pseudo-meningocele formation, cerebrospinal fluid leakage, or postoperative infection. The vicryl mesh served as a latticework for formation of a neodural membrane. Inflammatory or reactive response to vicryl mesh was minimal, and no adhesion to underlying neural structures was noted. The neodural membrane formed in the animals in which lyophilized dura was employed was usually thicker than those in which vicryl mesh was used and was associated with thick arachnoid-neural adhesions in two of eight animals. We believe vicryl mesh is a suitable dural substitute and offers promise for use in clinical situations.

Repair of spinal dural defects. An experimental study.

The search for an ideal substance for duraplasty has stimulated clinical and experimental investigations. To date a large number of materials have been employed for dural repair, although there is as yet no unanimity regarding the ideal material. Most of these studies have been concerned with cranial dura, and spinal duraplasty has received less attention. This study was designed to examine the repair of spinal dural defects in the dog. The materials chosen for this experiment were autologous fat, a polyester fiber mesh (Mersilene) and silicone-coated Dacron (Dura Film). Nineteen dogs were used in this study. Following lumbar laminectomy and the excision of elliptical pieces of dura (1.0 X 0.5 cm) at three noncontiguous levels, each of the defects was repaired using one of the three materials. Groups of animals were sacrificed at each of 3, 6, 12, and 24 weeks after dural repair. The lumbar region was removed en bloc and prepared for histological examination. Repair of the dural opening was achieved in all cases. The polyester fiber mesh was quite effective for dural repair, serving as a scaffold through which a neomembrane grew and united the dural edges. The results with autologous fat were similarly favorable. On the other hand, results with silicone-coated Dacron showed encapsulation by connective tissue, with the ventral aspect of the graft frequently compressing the underlying cord.

An unusual complication of Dura Film as a dural substitute. Report of two cases.

Two cases are presented in which the patients developed an unusual complication following the use of an artificial dural substitute, silicone-coated Dacron (Dura Film). Both patients had undergone removal of a tumor and involved dura. The first patient developed a very thick connective-tissue capsule of the graft material which simulated a recurrent tumor. The second patient developed an acute hemorrhage initially thought to be an acute subdural hematoma beneath the artificial dura 9 weeks after tumor removal and implantation of the graft. A review of the literature and proposed mechanisms of these complications are presented.

A new technique for making cortical incisions with minimal damage to cerebral tissue.

A new technique is described that minimizes the damage to neural tissues caused by the cortical incisions that must be made when operating on intracerebral or intraventricular lesions. Symmetric cortical incisions were made bilaterally in the same region of the middle suprasylvian gyrus in six dogs. Blunt dissection was performed on the right side. A new technique, which utilizes a balloon catheter, was employed on the left side. A greater hemiparesis was observed on the left side in all dogs. There was a mild but definite hemiparesis on the right side in four dogs, which improved within 2-3 days postoperatively. The dogs were killed on the sixth postoperative day. The Fink-Heimer technique for selective staining of degenerating axons and their terminal boutons was used to determine the extent of neuronal damage. Histologic studies support clinical observations in the experimental animal that the neural damage resulting from cortical incision is significantly decreased when the balloon catheter technique is applied.

Survival of autologous fat grafts in humans and in mice.

Autologous fat grafts have been used in a number of surgical procedures, yet properties of fat as a transplant material have remained unclear. This study was designed to compare experimental observations of subcutaneous fat grafts in mice with clinical observations of autologous fat grafts placed over the dura following laminectomy in humans. Subcutaneous fat grafts were observed daily in 75 CFl mice with the use of modified Algire back chambers. Grafts were examined histologically and histochemically at intervals up to 60 days after transplantation. Gross and microscopic observations suggest that fat grafts went through a period of initial breakdown of fat cells which was followed by revascularization. This resulted in normal appearing fat, although a smaller volume than the original graft. Three samples of autologous fat grafts from humans were removed during reoperation in the lumbar region up to 22 months after the original procedure. Histological examination revealed revascularized grafts reduced in size: the fat was normal and never replaced by scar tissue.

Craniovertebral anomalies.

We have tried to clarify this confusing area by demonstrating the common relationships of these abnormalities. The development of the craniovertebral junction was present in order to understand the formation of the anomalies discussed. The radiologic lines and measurements that have been described are actually to measure the degree of compromise of the functional size of the foramen magnum. This mechanical compromise, either from direct neural compression and/or from a secondary vascular impairment (arterial or venous), leads to the signs and symptoms of cervicomedullary compression.

Anterior cervical discectomy and interbody fusion. An experimental study using a synthetic tricalcium phosphate.

This study evaluates the histological and histochemical changes and osteogenicity of Synthos (tricalcium phosphate ceramic) implanted in the cervical intervertebral space. The cervical vertebrae from C-3 to C-6 were exposed in 20 dogs, and discectomy was performed at the third and fifth spaces. A dowel of Synthos was inserted into the third space, and a piece of fresh autologous graft from the humerus was inserted into the fifth space. The animals were divided into five groups with four animals in each. Four animals were sacrificed at each of 3, 6, 12, 18, and 22 weeks after the procedure. The C-3 to C-6 vertebrae were removed en bloc. One-half of each specimen was processed for histological examination of bone development, while the other half was processed for the two-color fluorescent labeling technique of Suzuki and Matthews for determination of osteogenesis at the time of operation and sacrifice. Various degrees of compression of the Synthos dowel were noted, with anterior and/or posterior displacement of the implant in 70% of the cases. Results indicate that the Synthos implant was biochemically and biomechanically unacceptable for the purposes of this investigation.