Phrenic paresis--a possible additional spinal cord dysfunction induced by neck manipulation in cervical spondylotic myelopathy (CSM): a report of two cases with anatomical and clinical considerations.

The clinical records of two male subjects with severe cervical spondylotic myelopathy (CSM) who developed respiratory insufficiency after the cervical manipulation involved in preoperative anesthetic intubation were examined. Their cervical imaging was analyzed with respect to the known anatomic relationships of the spinal phrenic nerve nuclei to the spondylotic compressive lesions in an attempt to provide the anatomic and pathologic rationales that may explain this phrenic paresis as a possible traumatic complication of severe CSM. Perusal of extant literature revealed extensive descriptions of CSM symptoms, but none had previously reported an associated neuromuscular weakness of the diaphragm. Magnetic resonance imaging analyses indicated that the existing degree of upper cervical cord compression, when reinforced by the additional posterior and anterior pressures consequent to cervical spinal extension and flexion, could readily account for the functional impairment of phrenic nerve neuron cells and/or their efferent fibers. Thus, the anatomic relations of the phrenic nerve nuclear columns and their efferent tracts predispose them to interference by compressive lesions found in CSM, and undue manipulation of the cervical spine when advanced stenosis is known to be present should be recognized as a possible cause of cervical spondylotic myelopathic-phrenic paresis.

Lumbosacral anterolateral spinal arteries and brief review of "accessory" longitudinal arteries of the spinal cord.

The lumbosacral anterolateral spinal arteries (LALSA) were studied in 14 injected lumbosacral spinal cords. Contrary to many previously published opinions, which claimed that virtually all of the formerly described "accessory" longitudinal arteries of the vasa corona, were too inconstant to be of significance, the LALSA in this series were reliably present bilaterally and averaged a length of 8.4 cm. They ran in the acute angles formed by the emergence of the fascicles of the lumbosacral anterior spinal nerve roots and in this position, served as the origin for most of the proximal radicular arteries that supply the cranial half of the motor roots of the cauda equina. A review of the literature and analysis of other accessory longitudinal spinal arteries revealed that two other pairs of accessory spinal vessels, the lateral cervical spinal arteries (LCSA) and the lateral spinal arterial axes (LSA), have a demonstrable functional role and were sufficiently constant, along with the LALSA, to warrant inclusion in detailed descriptions of human spinal cord vasculature.

Intimal musculature of the lower anterior spinal artery.

STUDY DESIGN: This was a descriptive microscopic investigation of the smooth musculature in the human lower anterior spinal artery using anatomic cadaver tissues with supporting data derived from angiographic studies of neonatal cadavers. OBJECTIVE: To determine the extent and configuration of the intimal musculature in the lower anterior spinal artery and deduce the probable influence it has on the lower spinal cord blood flow, as well as its effects on the axial anastomotic potentials during aortic cross-clamping. SUMMARY OF BACKGROUND DATA: The high incidence of ischemic spinal cord injury after aortic cross-clamping has led to many studies of autoregulation of the spinal cord blood flow, but none have identified the probable vascular mechanisms. METHODS: Spinal tissue blocks that included the mid-thoracic and thoracolumbar anterior spinal artery, and sections of excised anterior spinal artery were dissected from spinal cords of 16 cadavers, refixed in Bouin's solution, paraffin embedded, and microscopically studied in sections processed in Masson's trichrome stain. A radioangiographic study of barium-perfused spines of neonatal cadavers was used to substantiate histologic observations. RESULTS: The smooth muscle of the tunica media of the lower anterior spinal artery is reinforced by a conspicuous longitudinally disposed layer of intimal muscle. At the junction of the arteria medullaris magna and the anterior spinal artery, this muscle forms intimal cushions that can dramatically alter the luminal diameters of the vessels involved. CONCLUSION: The described muscular characteristics of the lower anterior spinal artery indicate it has a previously unsuspected capacity to control extrinsic and intrinsic aspects of the lower spinal cord blood flow, a factor that should be considered in clinical and experimental procedures involving spinal cord collateral circulation.

The infra-aortic arteries of the spine: their variability and clinical significance.

The infra-aortic spinal arteries caudal to the aortic bifurcation were studied in 20 perinatal and adult cadavers to determine their import relative to extraforaminal approaches to the lower lumbar discs as well as their probable involvement in certain cases of radiculomedullary ischemia. Analysis of these specimens indicated that, despite considerable variation, the arteries to the L4-L5 and L5-S1 intervertebral foramens generally were not related to the disc dorsolateral zones where lateral surgical approaches are best accomplished. Also, the frequency in which the fourth as well as the fifth lumbar and all sacral segmental vessels were dependent on the posterior division of the hypogastric artery may help explain how spinal cord ischemia could occur in individuals with vulnerable cord vascular patterns and/or spinal arteriopathy after interruption of hypogastric artery blood flow during pelvic operations.

The pial ligaments of the anterior spinal artery and their stretch receptors. A spinal cord distraction-sensing system?

The pial sheath of the anterior spinal artery displays a system of ligaments that course along the ventral surfaces of the anterior spinal artery and its medullary feeder arteries on the lower half of the spinal cord. Frequently, discrete ligamentous straps extend from these anterior spinal artery ligaments to the sheath of an anterior spinal nerve root to reinforce the general cauda equina pial connections to this system. Microscopy of ligament sections revealed that numerous Golgi-type neurofascicular receptors were oriented longitudinally among the ligament fascicles and associated with well-myelinated nerves. As this type of mechanoreceptor has been known only in association with stretch reflex mediation in the musculoskeletal system, it appeared likely that these anterior spinal artery ligaments and their homologous type of receptors may be implicated in sensing distraction of the thoracolumbar spinal cord and protectively modifying the actions of the involved spinal musculature.

Nonoperative treatment of acute hamate hook fractures.

Six patients with acute and two patients with subacute nondisplaced fractures of the hamate hook were treated with immobilization. The patients with acute fractures were treated within 7 days of the injury, and those with subacute fractures were treated after 7 days. Seven of the eight patients showed documented healing of their fractures. At follow-up (average 8 months) all seven were free of symptoms. One patient with a subacute fracture did not comply with treatment and had a painful nonunion. Our results show that hamate hook fractures that are diagnosed early may heal with nonoperative management. Fractures that fail to heal with immobilization or those with chronic nonunion should be treated with excision of the hook fragment.

Limitations of indium leukocyte imaging for the diagnosis of spine infections.

The usefulness of indium-111 white blood cell (WBC) scintigraphy in the detection of spine sepsis was studied in 22 patients who had open or percutaneous biopsies for microbiologic diagnosis. The indium images in 18 patients with vertebral infection were falsely negative in 15 (83%) and truly positive in 3 (17%). All four patients with negative cultures and histology had true-negative scans. The indium-111 WBC imaging results yielded a sensitivity of 17%, a specificity of 100%, and an accuracy rate of 31%. Prior antibiotic therapy was correlated with a high incidence of false-negative scans and photon-deficient indium-111 WBC uptake. The usefulness of indium-111 WBC scintigraphy for the diagnosis of vertebral infection may be limited to those patients who have not been treated with antibiotics previously.

A histological study of acute hematogenous osteomyelitis following physeal injuries in rabbits.

In young rabbits, the effects of an intravenous injection of Staphylococcus aureus alone, and in combination with a traumatic injury of the proximal tibial physis, were studied by light and electron microscopy. Metaphyseal osteomyelitis and radiographic changes were seen within forty-eight hours after the injury in all rabbits that had a growth-plate disruption and bacteremia. An intravenous injection of bacteria alone produced no morphological or microbiological evidence of infection. In the absence of trauma, normal tibiae were sterile after forty-eight hours. Foreign-body particles have been shown to accumulate in the fine vessels that are adjacent to the growth plate, but we found no similar deposition of bacteria or evidence of phagocytic removal in this area. Phagocytosis of bacteria by neutrophils did not appear to be impaired in the distal third of the metaphysis, but a delayed inflammatory response that allowed proliferation of bacteria and destruction of tissue was observed in the proximal two-thirds of the metaphysis after trauma.

The intrinsic vasculature of developing vertebral end plates and its nutritive significance to the intervertebral discs.

The structure and anatomical relationships of cartilage canals in the developing vertebral endplates of rabbits and humans are described in this study. In newborn rabbits, we observed a similar morphology and topologic arrangement to that in human fetal spines. Each vascular organ consisted of an arteriole, a glomerular tuft of sinusoidal capillaries, recurrent venules, and supporting loose connective tissue. Because the canals terminate adjacent to the intervertebral discs, they may provide an important source of nutrition to the disc during development when it is sandwiched between two layers of thick hyaline cartilage and contains no intrinsic vascular supply.