Jean Siegfried

Applied anatomy of the back

General Part..- I. Importance and Form of the Back.- II. Topography of the Back.- III. The Skeleton of the Back.- IV. The Musculature of the Back.- V. Outline of the Arteries of the Back.- VI. Outline of the Veins of the Back.- VII. Outline of the Lymphatic System of the Back.- VIII. The Nervous System of the Back.- IX. The Skin and Subcutis of the Back.- X. Clinical Investigation of the Back.- XI. Anatomy of Pain Conduction and Pain Perception.- Special Part. 2.- I. Vertebral Region.- II. Special Features of the Sectors of the Vertebral Region.- III. Paravertebral Regions.- References.

VOLUMESERIES: a software tool for target volume follow-up studies with computerized tomography and magnetic resonance imaging: Technical note

The purpose of this paper was to note a potential source of error in magnetic resonance (MR) imaging. Magnetic resonance images were acquired for stereotactic planning for GKS of a vestibular schwannoma in a female patient. The images were acquired using three-dimensional sequence, which has been shown to produce minimal distortion effects. The images were transferred to the planning workstation, but the coronal images were rejected. By examination of the raw data and reconstruction of sagittal images through the localizer side plate, it was clearly seen that the image of the square localizer system was grossly distorted. The patient was returned to the MR imager for further studies and a metal clasp on her brassiere was identified as the cause of the distortion.A-60-year-old man with medically intractable left-sided maxillary division trigeminal neuralgia had severe cardiac disease, was dependent on an internal defibrillator and could not undergo magnetic resonance imaging. The patient was successfully treated using computerized tomography (CT) cisternography and gamma knife radiosurgery. The patient was pain free 2 months after GKS. Contrast cisternography with CT scanning is an excellent alternative imaging modality for the treatment of patients with intractable trigeminal neuralgia who are unable to undergo MR imaging.The authors describe acute deterioration in facial and acoustic neuropathies following radiosurgery for acoustic neuromas. In May 1995, a 26-year-old man, who had no evidence of neurofibromatosis Type 2, was treated with gamma knife radiosurgery (GKS; maximum dose 20 Gy and margin dose 14 Gy) for a right-sided intracanalicular acoustic tumor. Two days after the treatment, he developed headache, vomiting, right-sided facial weakness, tinnitus, and right hearing loss. There was a deterioration of facial nerve function and hearing function from pretreatment values. The facial function worsened from House-Brackmann Grade 1 to 3. Hearing deteriorated from Grade 1 to 5. Magnetic resonance (MR) images, obtained at the same time revealed an obvious decrease in contrast enhancement of the tumor without any change in tumor size or peritumoral edema. Facial nerve function improved gradually and increased to House-Brackmann Grade 2 by 8 months post-GKS. The tumor has been unchanged in size for 5 years, and facial nerve function has also been maintained at Grade 2 with unchanged deafness. This is the first detailed report of immediate facial neuropathy after GKS for acoustic neuroma and MR imaging revealing early possibly toxic changes. Potential explanations for this phenomenon are presented.In clinical follow-up studies after radiosurgery, imaging modalities such as computerized tomography (CT) and magnetic resonance (MR) imaging are used. Accurate determination of the residual lesion volume is necessary for realistic assessment of the effects of treatment. Usually, the diameters rather than the volume of the lesion are measured. To determine the lesion volume without using stereotactically defined images, the software program VOLUMESERIES has been developed. VOLUMESERIES is a personal computer-based image analysis tool. Acquired DICOM CT scans and MR image series can be visualized. The region of interest is contoured with the help of the mouse, and then the system calculates the volume of the contoured region and the total volume is given in cubic centimeters. The defined volume is also displayed in reconstructed sagittal and coronal slices. In addition, distance measurements can be performed to measure tumor extent. The accuracy of VOLUMESERIES was checked against stereotactically defined images in the Leksell GammaPlan treatment planning program. A discrepancy in target volumes of approximately 8% was observed between the two methods. This discrepancy is of lesser interest because the method is used to determine the course of the target volume over time, rather than the absolute volume. Moreover, it could be shown that the method was more sensitive than the tumor diameter measurements currently in use. VOLUMESERIES appears to be a valuable tool for assessing residual lesion volume on follow-up images after gamma knife radiosurgery while avoiding the need for stereotactic definition.This study was conducted to evaluate the geometric distortion of angiographic images created from a commonly used digital x-ray imaging system and the performance of a commercially available distortion-correction computer program. A 12 x 12 x 12-cm wood phantom was constructed. Lead shots, 2 mm in diameter, were attached to the surfaces of the phantom. The phantom was then placed inside the angiographic localizer. Cut films (frontal and lateral analog films) of the phantom were obtained. The films were analyzed using GammaPlan target series 4.12. The same procedure was repeated with a digital x-ray imaging system equipped with a computer program to correct the geometric distortion. The distortion of the two sets of digital images was evaluated using the coordinates of the lead shots from the cut films as references. The coordinates of all lead shots obtained from digital images and corrected by the computer program coincided within 0.5 mm of those obtained from cut films. The average difference is 0.28 mm with a standard deviation of 0.01 mm. On the other hand, the coordinates obtained from digital images with and without correction can differ by as much as 3.4 mm. The average difference is 1.53 mm, with a standard deviation of 0.67 mm. The investigated computer program can reduce the geometric distortion of digital images from a commonly used x-ray imaging system to less than 0.5 mm. Therefore, they are suitable for the localization of arteriovenous malformations and other vascular targets in gamma knife radiosurgery.

Palliative treatment of brain metastases with gamma knife

The gamma knife is a stereotactic radiosurgery device which allows well defined, deep seated brain tumors or arteriovenous malformations with a maximal volume of about 25 ccm and a diameter not greater than 3.5 cm, to be treated in a single session under local anesthesia. The gamma knife offers an alternative treatment method to the classical approach of treating brain metastases by surgical excision and/or whole brain radiotherapy. The advantages of this technique are evident: the method is non-invasive, the treatment is carried out in a single session with a very short hospitalisation of two to three days, it is exempt from physical and psychical stress, the head does not need to be shaved and no hair loss occurs, a good quality of life is obtained for a reasonably prolonged survival time and it offers an economically favourable treatment method. Up to December 1999, over 30,000 patients suffering from brain metastases have been treated worldwide using the gamma knife. In Zürich, from September 1994 to December 2000 140 received this treatment. In the literature selection criteria may differ, and this may have determined some of differences in outcome. However, our results are comparable with those in the majority of publications with an average survival time of 263 days and a maximum survival of 1080 days. Good prognostic factors for survival and local control of brain metastases are a Karnofsky Performance Scale Score approaching 90 to 100, but not lower than 70, tumour volume, controlled primary cancer, and absence or stable extracranial metastases.

The Musculature of the Back

The skeletal musculature of our body is derived from the mesoderm. Muscles arise both from the primitive segments (somites) and from the nonsegmented mesoderm. In the back the latter furnishes the sternocleidomastoid and trapezius muscles, which are spoken of as visceral muscles to distinguish them from the somatic muscles. All the other muscles of the back originate from the somites or their derivatives.

Outline of the Veins of the Back

The venous drainage of the back can be divided into three outflow territories corresponding to the three major inflow territories of its arterial supply. Blood from the nuchal and shoulder regions drains into the right and left innominate veins (V. brachiocephalica). The thoracolumbar area is drained by the azygos vein and the lumbosacral area by the iliac veins. Longitudinal and transverse connexions between these territories are even more abundant on the venous side than on the arterial. Taken as a whole, they form a broad pathway between the superior and inferior venae cavae (Fig. 118).

The Skin and Subcutis of the Back

The skin over the back is considerably thicker than that of most other parts of the body. Its greater thickness is partly due to the more pronounced keratinization of the epidermis and partly to the robust layer of corium. Because of its toughness, the skin of the back is well able to resist trauma and for the same reason suppurative lesions do not easily break through it. The skin of the back is so inelastic that boils and carbuncles tend to cause greater tension and more pain than in other parts of the body. As a rule, the skin surface is divided into regular fields. Folds are not normally present, but in elderly people there may be transverse or oblique compression furrows on the nape of the neck. The orientation of the collagen fibers, as ascertained by Langer’s scarification method, is predominantly transverse, though they arch upwards between the shoulders (Fig. 167 a). Of more practical importance are the tension lines (Fig. 168). In the cervical and lumbar sectors they run for the most part transversely, but in the thoracic region they run vertically and form part of the long strands which encircle the shoulders.

Anatomy of Pain Conduction and Pain Perception

The commonest symptom of all back ailments is pain. Pain is a psychophysical experience rather than a specific sensory function. Pain comprises a chain of physiologic and mental reactions from the site of the stimulus to the highest centers (perception, location and assessment) and the resulting pain reactions (Struppler and Hiedl 1977).

Topography of the Back

The boundaries of the back are variously defined. The highest nuchal line is named as the upper boundary by some authors (e.g. Hafferl 1969) who therefore include the neck in the back, while the lines joining each acromial process to the spinous process of C VII are preferred by others (e.g. Tondury 1981). For some authors the back ends at the sacrum, which they include in the pelvis, for others it ends at the tip of the coccyx. We define the upper and lower limits of the back according to its anatomically and clinically most important structural elements, the vertebral column and its contents. Our upper limit is the highest nuchal line at the occipital region, our lower one the contour lines between the buttocks and the iliac crests, sacrum and coccyx (Fig. 10).

The Nervous System of the Back

The back contains part of the central nervous system, namely the spinal cord, which lies within the vertebral column. The roots and branches of the spinal nerves connect the cord with nearly all parts of the body. Furthermore, the sympathetic trunk is closely related to the spinal column, and the back is hence an important control center for most of the activities of the body.

Outline of the Lymphatic System of the Back

In the nuchal and shoulder regions all the lymph, from superficial and deep sources alike, flows into the cervical lymph nodes. In the other parts of the back, however, lymphatic drainage can be divided into superficial and deep systems. In the thoracic region lymphatics from the skin and subcutis drain into the axillary lymph nodes, and in the lumbosacral region they drain into the superficial inguinal nodes. Lymph from the musculoskeletal structures of this region is filtered by nodes which lie along the spine. To simplify this situation it may be said that in the back there is a superficial lymph flow which is directed laterally and a deep lymph flow directed medially (Fig. 121).