Biomedical subjects
Publications and source records attributed to P F Harris.
In appropriately selected patients, glomus tumors of the head and neck are best treated surgically. Unresectability is not a factor in therapeutic planning for local disease control. Existing techniques and exposures for tumor removal can be reliably applied to these paragangliomas, with acceptable morbidity and mortality. A team approach to this problem is mandatory.
Two hundred cases of head and neck cancer were reviewed and 16 pharyngocutaneous fistulas identified, for an incidence of 6 percent. The fistulas were closed with pectoralis major muscle flaps in four patients, pectoralis musculocutaneous flaps in seven patients, sternocleidomastoid muscle flaps in four patients, and latissimus dorsi flaps in two patients. Four types of fistulas were identified, and flap selection was determined by fistula location. Successful closure was obtained in 15 patients (88 percent), although one patient died from recurrence with a persistent fistula.
Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4-5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3-4, T7-8 and L2-3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65 degrees) than in the thoracic and lumbar discs (about 70 degrees). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.
Advances in microsurgical techniques, with the use of the laser and the ultrasonic suction aspirator, have paved the way for even more aggressive surgical approaches to large skull-base lesions, such as glomus tumors, adenocarcinomas of the temporal bone, and cranial nerve neuromas. Postoperative morbidity of multiple cranial nerve dysfunction has been aggravated in the past by cerebrospinal fluid leakage and/or gastro-intestinal dysfunction. At the Otology Group, P.C., in the course of dealing with more than 86 skull-base tumors, we have developed a standardized, multispecialty approach to such extensive skull-base lesions, including tracheotomy, gastrostomy, "ventriculoatrial" shunt placement, and rotated temporalis muscle flap closure. This article presents cases that illustrate the evolution of the current, "standard skull-base" operative procedure and the rationale for incorporation of the shunt and the muscle flap closure as operative refinements. Their beneficial effects upon postoperative morbidity are detailed.
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Some basic features in the development of the structure of the annulus fibrosus and nucleus pulposus in the rabbit, as described by previous workers, have been confirmed in the present study. However, the greater thickness of the anterior part of the disc, as compared with the posterior region, and the distinctive arrangement of lamellae in the posterior part of the disc, cannot be attributed, as conventionally claimed from studies of the human spine, to a secondary curvature in the lumbar spine associated with an upright posture: for these features are present in the lumbar spine of the quadrupedal rabbit with its primary curvature. Secondary ossification produces a plate-like epiphysis separating the growth cartilage from the intervertebral disc. A distinct cartilaginous plate, limiting the nucleus pulposus in the rabbit intervertebral disc, only becomes apparent when collagen fibres cease to traverse the area above and below the nucleus pulposus.
Regression equations are presented which describe the growth in length of the various regions of the vertebral column in the human fetus. From 8 weeks on the thoracic is always the longest region and the sacral the shortest, while the lumbar region is longer than the cervical. From the regression equations predictions of fetal vertebral length can be made from fetal age: this should be useful in obstetric practice when diagnostic ultrasound techniques are being employed for the diagnosis of growth disorders and skeletal abnormalities. A different developmental pattern emerges when average 'vertebral units' for each region are compared. The lumbar vertebrae are always the largest with the thoracic, cervical and sacral vertebrae being progressively smaller.
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Colour transparencies are prepared of a re-colourized anatomical specimen after placing labels temporarily in position to indicate specific structures. The specimen is also radiographed to show skeletal and soft tissue structures and radio-opaque materials and letters may used to indicate certain parts. Having mounted the specimen it can then be placed in a teaching carrel together with the radiographs and a back-slide projector for viewing the colour transparencies. The student is guided through an examination of the specimen using a script or soundtape. Frequent cross-reference is made between the actual specimen, the colour transparencies on which certain parts of the specimen have been labelled, and also the radiographs. The examination is followed by self-assessment questions relevant to the specimen and these may include identification of structures on a photograph of the specimen and on duplicate radiographs. In the final section of the aid, the answers of the self-assessment questions are given.
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The present study has shown that the secondary curvature in the cervical spine of the human fetus develops at a much earlier age than has been thought. It may, in fact, develop soon after the embryo first acquires a neck and begins to uncurl. The early appearance of this curvature may be related to the early development of function in the muscles responsible for head extension, this movement being a basic component of the primitive "gasp" reflex. It is further suggested that, although the embryo develops in flexion, the traditional assumption that such flexion is a consequence of fetal musculoskeletal development must be questioned, and the expression "normal fetal flexed position" is probably misleading, since it does not take into account the wide range of movements of which the fetus is capable.
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Human fetal movements in utero have been analysed by conventional compound B-scan ultrasound techniques. With practice, movements of specific parts of the fetus can be readily recognised, and even as early as the 6th week after conception gross movements of the whole embryo are visible. Monitoring of fetal movements as an indication of normal or abnormal fetal development appears to have been neglected, and future studies in this important area of antenatal paediatrics are suggested.
A radiological study has been made of the colon in 64 human fetuses between 11 and 20 weeks gestation (64-160 mm crown rump (CR) length). A dynamic picture of colon development was obtained from analysis of the radiographs. The findings challenge textbook descriptions, but can be interpreted in terms of the ultimate morphology of the colon. According to the morphology of the proximal (pre-splenic) part of the colon, there are three types of colon. In Type 1 it lies transversely, in Type 2 it is oblique in direction, and Type 3 has a postnatal form with ascending and transverse elements. Although the Type 1 predominates in smaller fetuses and the type 3 is most common in larger fetuses, there is some overlap in their distribution. The ileocaecal junction does not descend, but actually slightly ascends as the fetus grows. The splenic flexure grows in a distinctly cranial direction, and at almost three times the rate of the ileocaecal junction. Thus, as the fetus develops, the ileocaecal junction and splenic flexure grow further apart, and this determines the change from a Type 1 to a Type 2 colon. The divergence of the ileocaecal junction and splenic flexure appears to be related to different rates of growth in the colon, the distal (post-splenic) part growing almost half as fast again as the proximal (pre-splenic) part. The more mature (Type 3) form of colon appears to result from conversion of the Type 2 following early adhesion between the proximal colon and the second part of the duodenum.
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When data from various sources were compared, it was found that estimates of foetal age based upon crown-rump measurements varied considerably. These variations are probably related to the positions in which the foetuses were measured. Tables relating foetal age to foetal length should therefore specify the precise posture in which the foetus was placed for measurement. A standard readily reproducible position is proposed for the foetus when recording its length and it is suggested that crown-rump length should be related to "conceptual" age instead of the more conventional "menstrual" age.
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