Stewart B. Dunsker

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.

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. Moskowitzs 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.

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.

Port-access first-rib resection

Abstract. 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.

Traumatic narrowing of the dorsolumbar spinal canal demonstrated by computed tomography.

Evaluation of the dimensions of the spinal canal is difficult to achieve by conventional techniques. CT scanning permits accurate evaluation of the canal dimensions as well as comparison with levels above and below the site of injury. This report presents 3 cases of vertebral fractures in which narrowing of the spinal canal was demonstrated by CT.

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.

Extraforaminal lumbar arterial anatomy

BACKGROUND There are few studies carried out to reveal lumbar arterial anatomy. The studies of vascular anatomy of the lumbar zone are usually based on the angiographic imaging methods and barium injected radiographic sections of human specimens. METHODS Upon the recent breakthroughs in the microscopic anatomic dissections, the vascular structure of this zone is examined in 16 cadavers. Arterial anatomies of the extraforaminal zones of 80 lumbar vertebral objects were studied. RESULTS In each segment, lumbar artery, extraforaminal branches of the lumbar artery and the spinal (foraminal) branch were described. The spinal branch is originated from lumbar artery and extends as the dorsal branch. The dorsal branch is divided into 4 branches: ganglionic, transverse, ascending, and descending. Diameters of the lumbar artery, spinal, dorsal, and ganglionic branches were measured at each stage. The mean diameter of the lumbar artery was 2.7 mm, the dorsal branch was 2.0 mm, the foraminal branch was 1.9 mm, and the ganglionic branch was 1.0 mm, respectively. CONCLUSION Knowledge of lumbar arterial anatomy is needed for carrying out a successful surgical operation and reducing complications.

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.

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.

Contributions of johann jacob huber to the surface anatomy of the spinal cord and meninges: Commentary

FROM PREHISTORIC TIMES, man has been aware that injury to the spine may result in paralysis of the limbs; this is reflected in bas-relief figures found at Nineweh in ancient Mesopotamia, in a hunting scene that depicts a lioness wounded by King Ashurbanipal. The Edwin Smith papyrus gives many case illustrations of spinal cord injury resulting in paralysis, yet early physicians were unaware of the anatomy of the spinal cord. Galen performed prospective studies in animals by sectioning the spinal cord at varying levels and observing the commensurate paralysis and sensory loss. Real advances in the understanding of spinal cord anatomy did not occur until human cadaveric dissections were undertaken; even then, the knowledge of the anatomy of the spinal cord lagged behind that of other body structures. Johann Jacob Huber appears to be the first anatomist to focus on the spinal cord almost exclusively. His descriptions, and especially his illustrations that depict spinal cord surface anatomy, are impressive with regard to their accuracy and their sense of photorealism. Indeed, his illustrations seem to compare well with the anatomic drawings in contemporary anatomic texts. Yet, we were unable to find a single article in the entire English-language literature depicting his illustrations. We conclude that the description and anatomic illustrations by Johann Jacob Huber remain a hidden gem in the history of human spinal anatomy.