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Biomedical subjects

W W Parke

Publications and source records attributed to W W Parke.

At least 19 recordsLinked to original sources
PubMed2001

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.

Aged↗
PubMed1999

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.

Cadaver↗
PubMed1996

Malformations of the liver: some prenatal and postnatal developmental aspects.

The discovery of a large articulated lobe weighing 165.4 g dependent from the anterior margin of the left liver lobe in a 93-year-old female culminated two decades of observation of anomalous liver conditions in anatomic cadavers. When this data was compared with the information previously recorded from a series of 52 perinatal livers, remarkable discrepancies between the adult and perinatal incidences of various anomalous manifestations were noted. Ectopic accessory lobes were very rare in our adult series as well as in the groups reported in literature reviews. However, they were a relatively common occurrence in the perinatal cases, as were also gallbladder bridges of hepatic tissue, hypertrophic papillary lobes, and marked accessory fissures. In contradistinction, marginal accessory lobes were not noticed in any of the perinatal livers. Because the liver undergoes considerable postnatal reformation, it was concluded that most ectopic lobes, gallbladder bridges, hypertrophic caudate lobe extensions, and accessory fissures disappear during postnatal remodeling, whereas marginal accessory lobes may result from retention of the original perinatal boundaries of the anterior liver margins.

Aged↗
PubMed1996

Meningitis after adenoidectomy: an anatomic explanation.

Meningitis is a rare complication of adenoidectomy. During a 5-month period, two children at St Christopher's Hospital for Children developed meningitis within days following this surgical procedure. The potential causes of this complication that we investigated include coincidence, systemic hematogenous spread of bacteria to the central nervous system, and direct or indirect contamination of the cerebrospinal fluid by bacteria introduced by retropharyngeal injection of lidocaine hydrochloride and epinephrine. Based on statistical analysis of the available literature and anatomic studies of the pediatric nasopharyngeal region, we conclude that a retrograde flow of bacteria via a newly described anastomotic network of veins was the most likely cause of this sequela.

Adenoidectomy↗
PubMed1995

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.

Aged↗
PubMed1994

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.

Aged↗
PubMed1993

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.

Aged↗
PubMed1992

Avascular necrosis of the hamate: a case report with reference to the hamate blood supply.

Avascular necrosis of the hamate bone has not previously been reported. In this case the proximal fragment of the fractured hamate underwent avascular necrosis and prolonged healing. In an attempt to explain this sequela, angiography of the cadaver carpus followed by dissection of intact wrists and a study of enzyme-cleaned hamates showed that their wedge-shaped proximal segments were mostly enveloped by a distal extension of the midcarpal joint cavity and thus totally dependent on intraosseous nutrition. Consequently, the segment is at risk when a fracture line transects the body proximal to the base of the wedge. Clinically, this condition resulted in persistent discomfort and limitations of motion. A postinjury bone scan of the wrist indicated avascular changes in the proximal third of the hamate, and a delayed union was followed by later revascularization and a more normal scan image.

Accidents, Occupational↗
PubMed1991

The significance of venous return impairment in ischemic radiculopathy and myelopathy.

Because much of the symptomatology consequent to the constrictive lesions of spinal degenerations may be the result of radicular neurischemia, medullary neurischemia, or both, the structure and responses of the nerve root vasculature to compression or tension are discussed. Although the original investigations concentrated on the arterial side of the radiculomedullary circulation, more recent research has indicated that the venous return phase is far more susceptible to the effects of both intraspinal and extraspinal pathologic conditions.

Animals↗
PubMed1990

Adhesions of the ventral lumbar dura. An adjunct source of discogenic pain?

An analysis of the frequencies and locations of lumbar ventral dural adhesions was undertaken to ascertain their possible role in enhancing the low-back pain consequent to lumbar disc herniation. Data derived from a previous investigation, conducted for a different purpose, were incorporated with that of the presented study to provide a more extensive statistical base. Adhesions judged sufficient to possibly cause additional nerve disruption on separation were found in 16% of the specimens at the L3-4 level; 40% at the L4-5 level; and 36% at the L5-S1 level. Dural tissue segments, taken from the forcefully separated more firmly fixed adhesions found only at the L4-5 level, microscopically showed disruption of neurovascular bundles containing branches of the sinuvertebral nerve where they coursed between the adherent dura and the posterior longitudinal ligament. It was assumed that forced separation of adhesions during disc protrusion could add to perceived discomfort.

Aged↗
PubMed1987

Lumbosacral intersegmental epispinal axons and ectopic ventral nerve rootlets.

An epispinal system of motor axons virtually covers the ventral and lateral funiculi of the human conus medullaris between the L-2 and S-2 levels. These nerve fibers apparently arise from motor cells of the ventral horn nuclei and join spinal nerve roots caudal to their level of origin. In all observed spinal cords, many of these axons converged at the cord surface and formed an irregular group of ectopic rootlets that could be visually traced to join conventional spinal nerve roots at one to several segments inferior to their original segmental level; occasional rootlets joined a dorsal nerve root. As almost all previous reports of nerve root interconnections involved only the dorsal roots and have been cited to explain a lack of an absolute segmental sensory nerve distribution, it is believed that these intersegmental motor fibers may similarly explain a more diffuse efferent distribution than has previously been suspected.

Animals↗
PubMed1986

Vascular and neural pathology of lumbosacral spinal stenosis.

During a study of the intrinsic vasculature of the lumbosacral spinal nerve roots in cadavers, a typical case of spinal stenosis was encountered. A review of the antemortem anamnesis revealed that this patient had had an intermittent claudication of the cauda equina. Investigation of the concomitant vascular and histopathological alterations of the affected nerve roots suggested that the claudication may have resulted from ectopic nerve impulse discharges elicited by rapid changes in the blood supply following exertion. The unexpectedly slight apparent neural deficit relative to observed root damage may be attributed to a neuronal plasticity within the spinal cord that permitted functional compensations to develop during the slow acquisition of the chronic nerve root pathology.

Aged↗
PubMed1984

The pharyngovertebral veins: an anatomical rationale for Grisel's syndrome.

UNLABELLED: Non-traumatic subluxation of the atlanto-axial joint following peripharyngeal inflammation (Grisel's syndrome) has been attributed to laxity of the transverse ligament caused by hyperemia, but a satisfactory anatomical rationale for the association of these conditions has been lacking. Injection of the cervical epidural sinuses of a series of human perinatal cadavera showed retrograde filling of a previously undescribed system of veins with frequent lymphovenous anastomoses. This system appears to drain the posterosuperior pharyngeal region. CLINICAL RELEVANCE: Because of their direct connection with the periodontoidal venous plexus and the suboccipital epidural sinuses, the pharyngovertebral veins may provide a hematogenous route for the transport of peripharyngeal septic exudates and neoplastic cells to the upper cervical spinal structures and provide an anatomical explanation for the atlanto-axial hyperemia of Grisel's syndrome.

Adult↗
PubMed1982

Persistent left hepatic venous connection with the coronary sinus.

An anomalous direct connection between the left hepatic vein and the coronary sinus in two cadavers is described. The normal development of the central systemic venous system with particular reference to the hepatic region is reviewed and a possible explanation for the present configuration is put forth. Although this configuration of venous anomaly without abnormal shunting of blood is considered clinically insignificant, the association of cardiac arrhythmias with these variations heightens the importance of their identification.

Aged↗
PubMed1981

Arterial vascularization of the cauda equina.

UNLABELLED: Vascular injection of eleven perinates revealed that each lumbosacral spinal-nerve root received its intrinsic blood supply from both distal and proximal radicular arteries through which the blood flowed toward a mutual anastomosis in the proximal one-third of the root. Segmental arteries supplied the distal vessels while their proximal equivalents received blood from their respective anterior or dorsolateral spinal arteries, which derived their flow from the large, irregularly located medullary arteries. CLINICAL RELEVANCE: The region of relative hypovascularity formed below the conus by the combined areas of anastomoses in the cauda equina may provide an anatomical rationale for the suspected neuroischemic manifestations concurrent with degenerative changes in the lumbar spine.

Angiography↗