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The thoracic paraspinal line: Further significance
gin.Radiol. (1979) 30, 329-335
The Thoracic Paraspinal Line: Further Significance S,K. GUPTA and VIRINDER MOHAN
Department of Diagnostic Radiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India Three hundred and seventeen cases which included 100 normal individuals have been studied for roentgen : significance of the thoracic paraspinal line (TPL). The descending thoracic aorta greatly determines the course and configuration of the TPL. In a right-sided aorta, the TPL is seen on the right side as a mirror image o f a leftsided TPL. Lateral deviation of the TPL and descending aorta occur as an ageing process. In systemic hypertension where there is an aortic unfolding, the TPL also unfolds and the degree o f TPL deviation has a fair degree of linear relationship with the severity and duration of hypertension in young individuals. Most cases of rnitral valvular disease show lateral deviation of the TPL and descending aorta. In these cases the enlarged left atrium displaces the descending aorta and hence the posteromedial border of left lung posterolaterally tangential to the vertebral column resulting in deviation of the TPL and aorta. Perioesophageal spread o f carcinoma of the oesophagus into the posterior mediastinum is indicated by changes in pleuro-oesophageal interface and TPL. Mediastinal lymphadenopathy in cases of testicular turnouts may be detected by discovery of TPL deviation on frontal radiographs of the thoracic spine. In extradural masses such as granulomas, abscesses and metastatic deposits, the TPL shows a localised bulge corresponding to the clinical and myelographic level of spinal compression. The thoracic paraspinal line often called the 'paraspinal line of Brailsford' is a linear shadow seen on the left side of a frontal skiagram of the thoracic spine running almost parallel to the vertebral bodies from the level of 4th to the 1 lth or 12th thoracic veztebrae. Attention to this line was first drawn in an editorial by Doub and Camp in 1942. Subsequently Lachman (1942), Garland (1943) and Brailsford (1943) reported in detail its clinical significance. The roentgen diagnostic importance of the thoracic paraspinal line is now well known in osteomyelitis and in tuberculosis of the spine (Brailsford, 1943; Gupta and Tuli, 1971 ; Millard, 1963 ; Norman, 1962), aortic aneuryslns (Dalton and Schwartz, 1956), traumatic rupture of the aorta (Sanbord et al., 1970), Hodgkin's disease (Martin, 196,7; Witten et al., 1965), : neuroblastoma (Eklof and Goodling, 1967), pleural fluid (Trackler and Brinkler, 1966) and portal hypertension (Doyle et al., 1961). During the last eight years the author has further studied the subject and has found the thoracic paraspinal line to show clinically significant changes in systemic hypertension, mitral valvular disease, testicular malignancy, carcinoma of tile oesophagus and extradural masses. These clinical conditions and 100 healthy individuals of all age groups form the material for this study. MATERIALS AND METHODS Table l gives an analysis of the clinical material of this communication. In all these cases in addition Reprint requests: Dr S. K. Gupta, MD, Professor of Radiology, 7 Medical Enclave, Banaras Hindu University, Varanasi, India.
Table 1 - The thoracic paraspinal line - patients studied
Cases Normal individuals Systemic hypertension Mitral valvular disease Testicular turnouts Carcinoma of the oesophagus Extradural mass lesions
100 50 100 30 30 7
to other relevant clinical and radiological examinations, a frontal skiagram of the thoracic spine was obtained to visualise thoracic paraspinal line. OBSERVATIONS
A study of 100 normal individuals of all ages showed that the distance of the TPL measured from the 7th or 8th dorsal vertebral bodies varied from 6 to 8 mm below 40 years of age and 6 to 15 mm above 40 years. The distance of the TPL was less in younger individuals and continued to increase with age. In elderly persons, the descending aorta tended to unfold and the TPL followed the same outwardly convex course. A right-sided aorta was associated with a right-sided TPL. In infants and young children, the TPL was hardly discernible. In some individuals the TPL as well as the aortic shadows were not visible while in the others only the aortic line was visible (Fig. 1, 2). Fig. 3 shows schematically the three types of TPL and aortic courses. Fig. 4 is the transverse section at the level of the thoracic vertebra
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CLINICAL RADIOLOGY
.:2--,
......
Fig. 3 - Schematic diagram showing (A) TPL and aortic shadow, (B) No TPL but aortic shadow, and (C) Hardly any aortic shadow and no TPL.
Fig. 1 - Frontal skiagram of thoracic spine of an elderly individual showing outward convexity of TPL and deseending aorta.
Fig. 4 - Transverse section at the level of thoracic 7th vertebra to explain the genesis of TPL (see text) in the majority of individuals.
showing the sagittal course of the posteromedial border of left hmg producing the thoracic paraspinal line. Fig. 5a shows prespinal location of aorta thus accounting for no aortic and no TPL shadow. Fig. 5b depicts the genesis o f an aortic shadow with. out TPL.
Hypertension
(a) (b) Fig. 2 - (a) Thoracic spine x-ray showing aortic shadow but not TPL shadow. (b) Thoracic spine x-ray showing no TPL. Aortic shadow is seen only in the upper part.
Thirty-five out of 50 cases o f systemic hypertension showed lateral deviation of the TPL and also o f the descending thoracic aorta_ There was a fair degree of linear relationship between the deviation o f TPL and the degree and duration of the h y p e r t e n s i o n (Fig. 6). Patients with higher blood pressures and long-standing hypertension showed marked deviation of the TPL as well as the aorta. I~ patients in w h o m hypertension was suspected and
331
THE THORACIC PARASPINAL LINE
(a) Fig. 5 - Transverse section at the level of 7th thoracic vertebra to explain variation in the course of aorta and TPL_ (A) Aortais prespinal and does not project away from the lateral ~vertebralborder. The posteromedial border of the left lung ~hasan oblique course like the right and hence there is no TPLand no aortic shadow. (B) Aorta is paraspinal in location buton a plane anterior to spine and does not encounter the p0steromedial border of the left lung. In such a situation ~ereis an aortic shadow but no TPL. discovered incidentally from the frontal skiagram o f the dorsal spine, the degree o f TPL deviation gave a rough estimate of duration of the disease having a :fair degree of correlation with hypertension changes in the fundus. These deviations were of significance 0nly in young patients below the age o f 40. In elderly patients suffering from hypertension where lateral deviation of the TPL and aorta occurred normally as an ageing process this observation could not be considered for evaluation o f hypertension. ~tral Valvular Disease One hundred cases of mitral valvular disease, all below the age of 40 years, were studied. Diagnostic criteria o f selection of these patients were clinical, ~lectrocardiographic and radiographic. Cases with ~ither pure or dominant mitral stenosis were assessed. In all these cases a frontal grid roentgenogram o f the thoracic spine in recumbent posture with or without an oesophagram was included. A separate oesophagram in the frontal projection was also obtained in
(b)
Fig. 6 - (a) Showing marked deviation of TPL and descending aorta in a 39-year-old patient suffering from systemic
hypertension (180/140) of only six years' duration- (b) Showing marked deviation of TPL and descending aorta in a 45-year-old patient suffering from systemic hypertension (170/110) of only four years' duration_ most of the cases. There was a mild, moderate or marked lateral deviation o f the TPL and descending aorta in 80% o f patients (Fig. 7). In all these patients there was gross left atrial enlargement. The oesophageal displacement in the frontal roentgenogram was mostly right-sided and bore no significant correlation with changes in the TPL and descending aorta. Twenty patients of mitral valvular disease did not show these changes despite other radiographic evidence of left atrial enlargement (Fig. 8). Testicular Tumours Thirty cases of histologically proven malignant testicular tumours were selected for any evidence of the TPL displacement by posterior mediastinal lymph nodes. Most patients had come for follow-up after initial treatment. They often came with either local recurrence or further extension o f the disease. Six out of 12 patients showing TPL deviation also had other evidence of intrathoracic extension o f disease in the form of pulmonary metastasis and pleural fluid. In the other six, intrathoracic extension of disease was indicated by TPL deviation alone. Four of these six patients had no palpable abdominal lymph nodes. On the basis of TPL deviation indicating posterior
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CLINICAL RADIOLOGY
Fig. 7 -- A case o~"mitral stenosis showing moderate deviation of TPL and aorta. Other features of marked left atrial enlargement are present,
(a) (b) Fig. 9 - (a) - Localised TPL deviation (arrows) in a ease0f testicular malignancy without any other evidence of intra, thoracic extension of disease. There were no Palpable abdominal lymph nodes. (b) - Localised deviation of TPL (arrows) in a case of testicular tumour also showing multiple pulmonary, metastasis.
!
Fig. 8 A case of mitral stenosis showing evidence of left atrial enlargement but no TPL deviation. mediastinal lymphadenopathy, i n c l u d e d in t h e r a d i a t i o n field the mode of lymphatic spread It is o b v i o u s t h a t m e d i a s t i n a l involved without involvement nodes.
the mediastinmn was (Fig. 9). Fig 10 gives of testicular tumours. l y m p h n o d e s c a n be of abdominal lymph
.a
L/
i
i
Fig. 10 - Line diagram showing mode of lymphatic sprea! of testicular tumours. Some of the lymphatics from testis reach the mediastinum directly without being intercepted by abdominai lymph nodes. i
THE
THORACIC
PARASPINAL
LINE
333
Fig. 11 - Frontal skiagram of thoracic spine in a case of 0¢s0phagealcancer showing bilateral displaced TPL shadows Indicatingextensive mediastinal involvement.
fjreinoma of the Oesophagus Thirty cases of carcinoma o f the oesophagus (histologically confirmed) were studied for any evidence of peri-oesophageal spread of disease in the mediastinum. Most o f these patients had fairly advanced disease. Sixteen patients showed a variable degree of mediastinal spread either by showing alteration of pleuro-oesophageal interface or TPL changes. Clinically these patients presented with dysphagia, weight loss and anaemia. Three patients in these series showed a large filling defect on the oesophagram, relatively short history of dysphagia and ana: plastic appearance on histological examination (Fig. 11).
ExtraduralMass Lesions Seven cases o f extradural mass lesions of the thoracic paraspinal canal were studied. These consisted of five extradural granulomas or abscesses, one of Hodgkin's disease and one of axillary lymphosarcoma metastating into the thoracic extradural space. All these patients presented with compression paraparesis or paraplegia. CSF proteins were raised. A block was found in cases where myelography was done. TPL deviation was seen in all seven cases and e0rresponded to the spinal level of neurologic deficit and myelographic block (Figs 12, 13). There was no radiographic evidence of disease of adjacent verte-
(a) (b) Fig- 12 - (a) Frontal myelogram ha a case of surgically proven extradural granuloma showing maxked TPL deviation and extradural type of myelographic block. There is no vertebral lesion. (b) Frontal myelogram in another case of extradural granuloma showing extradural type of complete myelographic block and localised TPL deviation (lower arrow). The upper arrow shows normal position of TPL. brae. Granulomas and abscesses were either tuberculous or non-specific in nature. DISCUSSION The thoracic paraspinal line (TPL) is a linear shadow seen on the left side of thoracic spine extending from the level of the 4th thoracic vertebral body to the l l t h or 12th thoracic vertebral body running roughly parallel to the vertebral bodies. It is produced by the posteromedial border of the left lung and its adjacent pleural covering. The linear shadow results from the fact that on the lung side the tissue is relatively radiolucent whereas on the vertebral side the tissue is radio-opaque. Tire descending thoracic aorta being more opaque than the lung is also seen as a linear shadow lateral to the thoracic paraspinal line. On the right side due to the obliquity of posteromedial border, there is absence of direct sagittal course of the pleura and posteromedial border o f the right lung and hence there is no TPL. However, in the presence of disease on the vertebral side, the lung is pushed laterally in a direct sagittal plane and a right-sided TPL is produced.
334
CLINICAL RADIOLOGY
deviation may provide a rough estimate of du .... of the hypertension. However, m elderly mdlvidual~ suffering from hypertension, where a TPL aad aortic deviation occur normally as an ageing Process, t ~ observation is of little significance for evaluation oF hypertension. In this study in addition to lateral deviation oft_he thoracic aorta described by Dee (1974) and Shanks and Kerley (1962) in left atrial enlargement TPLwas also found to show lateral deviation in 80% of cases. Selection of patients below the age of 40 in the present series as well as in the series analysed by Dee (1974) was mandatory to avoid interpreting similar Changes occurring normally in persons above the age of 40 years even without left atrial enlargement, ltis postulated that globular enlargement of a left atrium, in individuals with narrow mediastinums, displaces the descending aorta and hence the posteromedial border of the left lung posterolaterally tangential to the vertebral column resuRing in deviation of descend. ing aorta and the TPL. Absence of these changes in 20% of cases is thought to be due to a larger medias, tinum, the enlarged left atrium assuming a pear shape remaining well in front of the spine. A variable course of the aorta in relation to the left atrium may be another factor determining the presence or absence of these changes in mitral valvular disease. Based on the knowledge of TPL deviation as an addition of medistinal lymphadenopathy in Hodgkin's disease (Martin, 1967; Witten etal., 1965) we have added two more conditions, i.e. carcinoma of the oesophagus and testicular turnouts producing TPL changes due to involvement of the mediastinum. Peri-oesophageal spread of carcinoma of the oesophagus into the posterior mediastinum though considered:rare (Daniel e t at., 1960; Frazer, 1970) does OCcur and i s thought to be responsible for unsatisfactm3r response to all methods of treat, ment. When the tumour spreads in the mediastinum in a plane anterior to the spine, paraspinal masses are seen due to changes in pleuro-oesophageat interface but without any change in the TPL. However, when the involvement i of the mediastinum is gross the posteromedial'b0rder of the lung is affected and there is alteration of the TPU It can, therefore, be reasoa' ably assumed" 'that TPL deviation indicates fairly advanced disease. Detectioia ~of metastatic spread of testicula~ tumours into the abdominal and mediastinal lympt~ nodes is of gFeat importance in staging the disease and subsequent decision of the extent of radiation treatment.:,All malignant tumours of the testis are characterised by early metastasis into lymph nodeS, First to be involved are the upper lumbar, then the epigastric or paraortic and then the disease spreads •
Fig. 13 - TPL deviation in a case of axillary lymphosarcoma metastasising into the extradural space. The patient developed paraplegia_ There is no vertebral lesion.
The distance of the TPL measured from the bodies of vertebrae varies from 6 to 8 m m in individuals below the age of 40 years and 6 to 15 mm above the age of 40 years. Figures given for the second category of individuals by Doyle et al. (1961) were 6 - 1 9 r a m . In elderly individuals the descending thoracic aorta tends to swing around and unfold; the TPL follows a similar outward convex course. In infants and young children~ the TPL and sometimes even the descending aorta are hardly discernible because of the small aorta and its prespinal location and less development of the posteromedial border of the left lung. In some individuals the aorta is completely prespinal and there is no aortic and no TPL shadow. There are a few individuals where there is an aortic shadow but no TPL shadow, In such cases though the aorta is in a plane anterior to the vertebral bodies it projects beyond the lateral vertebral border. Airight-sided aorta is associated with a right-sided TPL. It is concluded from these observations that anatomical and physiological variations in descending aorta are closely reflected on the course and direction of the TPL. In systemic hypertension where there is aortic unfolding, the TPL also unfolds and the degree of TPL deviation has a fair degree of linear correlation with severity and duration of hypertension• The TPL deviation may be accepted as a new and subsidiary radiographic sign of systemic hypertension especially in young patients. In young patients in whom hypertension is discovered incidentally, the degree of TPL
•
.
.
"qtlOll
THE THORACIC PARASPINAL LINE aloog the prevertebral chain to the posterior mediastinal lymph nodes. Some of the lymphatics from the testis, however, reach the mediastinum directly, ~,ithout being intercepted by abdominal lymph ~0des. Thus it can be assumed that mediastinal h nodes may be involved without involvement igastric lymph nodes. Twelve cases showing TPL deviation indicating mediastinal involvement out of 30 cases of testicular tumour is a very high incidence and the need for search for this involvement in all caseS is stressed. In the absence of other evidence of intrathoracic disease and palpable abdominal lymph nodes, the TPL deviation seen on the dorsal spine radiograph assumes great clinical significance as in sach cases the mediastinum which otherwise would not be considered fo~ inclusion in the radiation treatment will be included in the radiation field and enhance the therapeutic efficacy of treatment. Lyrnphography, mediastinography, mediastinal biopsy and azygos venography are other methods to assess mediastinal involvement but they are technically difficult and not without risk to the patient and hence not employed by us in routine clinical practice. Extradural granulomas or abscesses of the thoracic spinal canal usually present with paraparesis or paraplegia. Results of early decompression are good. Decompression if delayed may result in irreversible damage to the spinal cord; this is especially true of extradural abscesses. Various parameters of diagnosis Of spinal compression is such cases are rise in CSF proteins and finding of myelographic block. There is often no radiographic evidence of contiguous bone involvement. Presence of TPL deviation corresponding to clinical and myelographic block found in the present series is an interesting new finding. It is postulated that extradural pathological process in the thoracic spinal canal which is not a watertight compartment extends outside through the intervertebral foramina into the thoracic paravertebral region and displaces the posteromedial border of left lung resulting in TPL deviation. It is surprising that authors who have reported on the subject have no mention of TPL devia(ion. It is probable that there was no special awareness to look for this sign. Similarly, metastatic extradural masses produce lateral deviation of TPL. Acknowledgements. The author thanks Dr K. N. Udupa, FACS, FRCS, FAMS, Director, Institute of Medical Sciences,
335
for his kind permission to publish this paper. His thanks are also due to Shri D. K. Mathur for photography and Shri Suraj Lal for secretarial assistance.
REFERENCES
Braflsford, J. F. (1943). The radiologic postero-medial border of lung or linear paraspinal shadow. Radiology, 41, 34-37. Dalton, C. J- & Schwartz, S. S. (1956). Evaluation of thoracic paraspinal line in roentgen examination of thorax. Radiology, 66,195--200. Daniel, R. A., Diveley, W. L., Edwards, W. H. & Chamberlain, N. (1960). Mediastinal turnouts. Annals of Surgery, 151, 783-793. Dee, P. M. (1974). Deviation of descending thoracic aorta as a sign of left atrial enlargement. Radiology, 112, 57-59. Doub, C. J. & Camp, J. D. (1942). The linear thoracic paraspinal shadow. Radiology, 41, 34-37. Doyle, F. B., Read, A. E. & Evans, K. T. (1961). The mediastinum in portal hypertension. Clinical Radiology, 12, 114-129. Eklof, O. & Goodling, G. A. (1967). Paravertebral widening in cases of neuroblastoma. British Journal o/Radiology, 40, 350-365. Frazer, R. G. & Pare, A. P. (1970). Diagnosis of Diseases of Chest. W. B. Saunders Co., Philadelphia. Garland, H. (1943). The postero-medial pleural line. Radiolog?l, 41, 29 33. Gupta, S. K. & Tuli, S. M. (1971). Roentgen evaluation of linear thoracic paraspinal shadow. Indian Journal of Radiology; 25, 189-194. Lachman, E. (1942). A comparison of posterior boundaries of lungs and pleura as demonstrated on the cadavers and on roentgenograms of living. Anatomical Record, 83, 621_ Martin, J. J. (1967). The Nisbet Symposium. Hodgkin's Disease. Radiologic Aspects, 11, 206 -218. Millard, D- C. (1963). Displacement of linear thoracic paraspinal shadow of Brailsford. An early sign in osteomyelitis of thoracic spine. American Journal of Roentgenology, 90, 1231- 1235. Norman, A. (1962). Segmental bulge of lineaI paraspinal shadow, an early sign of diseases of thoracic spine. Journal of Bone and Joint Surgery, 44A, 358 362. Sanbor, T. C, Heitzman, R. E- & Markanan, B. (1970). Traumatic rupture of aorta. Radiology, 95, 293 295. Shanks, S. C. & Kerley, P. (1962). Textbook of X-ray diagnosis_ Chest Volume_ H_ K. Lewis & Co., London. Trackler, R. T. & Brinker, R. A. (1966). Wideningof left paravertebral hne on supine chest roentgenograms in free pleural fluid. American Journal of Roentgenology, 96, 1027-1034. Witten, R. M., Fayos, J. V., & Larnpe, I. (1965). The dorsal paraspinal mass in Hodgkin's disease. American Journal of Roentgenology, 94,947-951.
The Thoracic Paraspinal Line: Further Significance S,K. GUPTA and VIRINDER MOHAN
Department of Diagnostic Radiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India Three hundred and seventeen cases which included 100 normal individuals have been studied for roentgen : significance of the thoracic paraspinal line (TPL). The descending thoracic aorta greatly determines the course and configuration of the TPL. In a right-sided aorta, the TPL is seen on the right side as a mirror image o f a leftsided TPL. Lateral deviation of the TPL and descending aorta occur as an ageing process. In systemic hypertension where there is an aortic unfolding, the TPL also unfolds and the degree o f TPL deviation has a fair degree of linear relationship with the severity and duration of hypertension in young individuals. Most cases of rnitral valvular disease show lateral deviation of the TPL and descending aorta. In these cases the enlarged left atrium displaces the descending aorta and hence the posteromedial border of left lung posterolaterally tangential to the vertebral column resulting in deviation of the TPL and aorta. Perioesophageal spread o f carcinoma of the oesophagus into the posterior mediastinum is indicated by changes in pleuro-oesophageal interface and TPL. Mediastinal lymphadenopathy in cases of testicular turnouts may be detected by discovery of TPL deviation on frontal radiographs of the thoracic spine. In extradural masses such as granulomas, abscesses and metastatic deposits, the TPL shows a localised bulge corresponding to the clinical and myelographic level of spinal compression. The thoracic paraspinal line often called the 'paraspinal line of Brailsford' is a linear shadow seen on the left side of a frontal skiagram of the thoracic spine running almost parallel to the vertebral bodies from the level of 4th to the 1 lth or 12th thoracic veztebrae. Attention to this line was first drawn in an editorial by Doub and Camp in 1942. Subsequently Lachman (1942), Garland (1943) and Brailsford (1943) reported in detail its clinical significance. The roentgen diagnostic importance of the thoracic paraspinal line is now well known in osteomyelitis and in tuberculosis of the spine (Brailsford, 1943; Gupta and Tuli, 1971 ; Millard, 1963 ; Norman, 1962), aortic aneuryslns (Dalton and Schwartz, 1956), traumatic rupture of the aorta (Sanbord et al., 1970), Hodgkin's disease (Martin, 196,7; Witten et al., 1965), : neuroblastoma (Eklof and Goodling, 1967), pleural fluid (Trackler and Brinkler, 1966) and portal hypertension (Doyle et al., 1961). During the last eight years the author has further studied the subject and has found the thoracic paraspinal line to show clinically significant changes in systemic hypertension, mitral valvular disease, testicular malignancy, carcinoma of tile oesophagus and extradural masses. These clinical conditions and 100 healthy individuals of all age groups form the material for this study. MATERIALS AND METHODS Table l gives an analysis of the clinical material of this communication. In all these cases in addition Reprint requests: Dr S. K. Gupta, MD, Professor of Radiology, 7 Medical Enclave, Banaras Hindu University, Varanasi, India.
Table 1 - The thoracic paraspinal line - patients studied
Cases Normal individuals Systemic hypertension Mitral valvular disease Testicular turnouts Carcinoma of the oesophagus Extradural mass lesions
100 50 100 30 30 7
to other relevant clinical and radiological examinations, a frontal skiagram of the thoracic spine was obtained to visualise thoracic paraspinal line. OBSERVATIONS
A study of 100 normal individuals of all ages showed that the distance of the TPL measured from the 7th or 8th dorsal vertebral bodies varied from 6 to 8 mm below 40 years of age and 6 to 15 mm above 40 years. The distance of the TPL was less in younger individuals and continued to increase with age. In elderly persons, the descending aorta tended to unfold and the TPL followed the same outwardly convex course. A right-sided aorta was associated with a right-sided TPL. In infants and young children, the TPL was hardly discernible. In some individuals the TPL as well as the aortic shadows were not visible while in the others only the aortic line was visible (Fig. 1, 2). Fig. 3 shows schematically the three types of TPL and aortic courses. Fig. 4 is the transverse section at the level of the thoracic vertebra
330
CLINICAL RADIOLOGY
.:2--,
......
Fig. 3 - Schematic diagram showing (A) TPL and aortic shadow, (B) No TPL but aortic shadow, and (C) Hardly any aortic shadow and no TPL.
Fig. 1 - Frontal skiagram of thoracic spine of an elderly individual showing outward convexity of TPL and deseending aorta.
Fig. 4 - Transverse section at the level of thoracic 7th vertebra to explain the genesis of TPL (see text) in the majority of individuals.
showing the sagittal course of the posteromedial border of left hmg producing the thoracic paraspinal line. Fig. 5a shows prespinal location of aorta thus accounting for no aortic and no TPL shadow. Fig. 5b depicts the genesis o f an aortic shadow with. out TPL.
Hypertension
(a) (b) Fig. 2 - (a) Thoracic spine x-ray showing aortic shadow but not TPL shadow. (b) Thoracic spine x-ray showing no TPL. Aortic shadow is seen only in the upper part.
Thirty-five out of 50 cases o f systemic hypertension showed lateral deviation of the TPL and also o f the descending thoracic aorta_ There was a fair degree of linear relationship between the deviation o f TPL and the degree and duration of the h y p e r t e n s i o n (Fig. 6). Patients with higher blood pressures and long-standing hypertension showed marked deviation of the TPL as well as the aorta. I~ patients in w h o m hypertension was suspected and
331
THE THORACIC PARASPINAL LINE
(a) Fig. 5 - Transverse section at the level of 7th thoracic vertebra to explain variation in the course of aorta and TPL_ (A) Aortais prespinal and does not project away from the lateral ~vertebralborder. The posteromedial border of the left lung ~hasan oblique course like the right and hence there is no TPLand no aortic shadow. (B) Aorta is paraspinal in location buton a plane anterior to spine and does not encounter the p0steromedial border of the left lung. In such a situation ~ereis an aortic shadow but no TPL. discovered incidentally from the frontal skiagram o f the dorsal spine, the degree o f TPL deviation gave a rough estimate of duration of the disease having a :fair degree of correlation with hypertension changes in the fundus. These deviations were of significance 0nly in young patients below the age o f 40. In elderly patients suffering from hypertension where lateral deviation of the TPL and aorta occurred normally as an ageing process this observation could not be considered for evaluation o f hypertension. ~tral Valvular Disease One hundred cases of mitral valvular disease, all below the age of 40 years, were studied. Diagnostic criteria o f selection of these patients were clinical, ~lectrocardiographic and radiographic. Cases with ~ither pure or dominant mitral stenosis were assessed. In all these cases a frontal grid roentgenogram o f the thoracic spine in recumbent posture with or without an oesophagram was included. A separate oesophagram in the frontal projection was also obtained in
(b)
Fig. 6 - (a) Showing marked deviation of TPL and descending aorta in a 39-year-old patient suffering from systemic
hypertension (180/140) of only six years' duration- (b) Showing marked deviation of TPL and descending aorta in a 45-year-old patient suffering from systemic hypertension (170/110) of only four years' duration_ most of the cases. There was a mild, moderate or marked lateral deviation o f the TPL and descending aorta in 80% o f patients (Fig. 7). In all these patients there was gross left atrial enlargement. The oesophageal displacement in the frontal roentgenogram was mostly right-sided and bore no significant correlation with changes in the TPL and descending aorta. Twenty patients of mitral valvular disease did not show these changes despite other radiographic evidence of left atrial enlargement (Fig. 8). Testicular Tumours Thirty cases of histologically proven malignant testicular tumours were selected for any evidence of the TPL displacement by posterior mediastinal lymph nodes. Most patients had come for follow-up after initial treatment. They often came with either local recurrence or further extension o f the disease. Six out of 12 patients showing TPL deviation also had other evidence of intrathoracic extension o f disease in the form of pulmonary metastasis and pleural fluid. In the other six, intrathoracic extension of disease was indicated by TPL deviation alone. Four of these six patients had no palpable abdominal lymph nodes. On the basis of TPL deviation indicating posterior
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CLINICAL RADIOLOGY
Fig. 7 -- A case o~"mitral stenosis showing moderate deviation of TPL and aorta. Other features of marked left atrial enlargement are present,
(a) (b) Fig. 9 - (a) - Localised TPL deviation (arrows) in a ease0f testicular malignancy without any other evidence of intra, thoracic extension of disease. There were no Palpable abdominal lymph nodes. (b) - Localised deviation of TPL (arrows) in a case of testicular tumour also showing multiple pulmonary, metastasis.
!
Fig. 8 A case of mitral stenosis showing evidence of left atrial enlargement but no TPL deviation. mediastinal lymphadenopathy, i n c l u d e d in t h e r a d i a t i o n field the mode of lymphatic spread It is o b v i o u s t h a t m e d i a s t i n a l involved without involvement nodes.
the mediastinmn was (Fig. 9). Fig 10 gives of testicular tumours. l y m p h n o d e s c a n be of abdominal lymph
.a
L/
i
i
Fig. 10 - Line diagram showing mode of lymphatic sprea! of testicular tumours. Some of the lymphatics from testis reach the mediastinum directly without being intercepted by abdominai lymph nodes. i
THE
THORACIC
PARASPINAL
LINE
333
Fig. 11 - Frontal skiagram of thoracic spine in a case of 0¢s0phagealcancer showing bilateral displaced TPL shadows Indicatingextensive mediastinal involvement.
fjreinoma of the Oesophagus Thirty cases of carcinoma o f the oesophagus (histologically confirmed) were studied for any evidence of peri-oesophageal spread of disease in the mediastinum. Most o f these patients had fairly advanced disease. Sixteen patients showed a variable degree of mediastinal spread either by showing alteration of pleuro-oesophageal interface or TPL changes. Clinically these patients presented with dysphagia, weight loss and anaemia. Three patients in these series showed a large filling defect on the oesophagram, relatively short history of dysphagia and ana: plastic appearance on histological examination (Fig. 11).
ExtraduralMass Lesions Seven cases o f extradural mass lesions of the thoracic paraspinal canal were studied. These consisted of five extradural granulomas or abscesses, one of Hodgkin's disease and one of axillary lymphosarcoma metastating into the thoracic extradural space. All these patients presented with compression paraparesis or paraplegia. CSF proteins were raised. A block was found in cases where myelography was done. TPL deviation was seen in all seven cases and e0rresponded to the spinal level of neurologic deficit and myelographic block (Figs 12, 13). There was no radiographic evidence of disease of adjacent verte-
(a) (b) Fig- 12 - (a) Frontal myelogram ha a case of surgically proven extradural granuloma showing maxked TPL deviation and extradural type of myelographic block. There is no vertebral lesion. (b) Frontal myelogram in another case of extradural granuloma showing extradural type of complete myelographic block and localised TPL deviation (lower arrow). The upper arrow shows normal position of TPL. brae. Granulomas and abscesses were either tuberculous or non-specific in nature. DISCUSSION The thoracic paraspinal line (TPL) is a linear shadow seen on the left side of thoracic spine extending from the level of the 4th thoracic vertebral body to the l l t h or 12th thoracic vertebral body running roughly parallel to the vertebral bodies. It is produced by the posteromedial border of the left lung and its adjacent pleural covering. The linear shadow results from the fact that on the lung side the tissue is relatively radiolucent whereas on the vertebral side the tissue is radio-opaque. Tire descending thoracic aorta being more opaque than the lung is also seen as a linear shadow lateral to the thoracic paraspinal line. On the right side due to the obliquity of posteromedial border, there is absence of direct sagittal course of the pleura and posteromedial border o f the right lung and hence there is no TPL. However, in the presence of disease on the vertebral side, the lung is pushed laterally in a direct sagittal plane and a right-sided TPL is produced.
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CLINICAL RADIOLOGY
deviation may provide a rough estimate of du .... of the hypertension. However, m elderly mdlvidual~ suffering from hypertension, where a TPL aad aortic deviation occur normally as an ageing Process, t ~ observation is of little significance for evaluation oF hypertension. In this study in addition to lateral deviation oft_he thoracic aorta described by Dee (1974) and Shanks and Kerley (1962) in left atrial enlargement TPLwas also found to show lateral deviation in 80% of cases. Selection of patients below the age of 40 in the present series as well as in the series analysed by Dee (1974) was mandatory to avoid interpreting similar Changes occurring normally in persons above the age of 40 years even without left atrial enlargement, ltis postulated that globular enlargement of a left atrium, in individuals with narrow mediastinums, displaces the descending aorta and hence the posteromedial border of the left lung posterolaterally tangential to the vertebral column resuRing in deviation of descend. ing aorta and the TPL. Absence of these changes in 20% of cases is thought to be due to a larger medias, tinum, the enlarged left atrium assuming a pear shape remaining well in front of the spine. A variable course of the aorta in relation to the left atrium may be another factor determining the presence or absence of these changes in mitral valvular disease. Based on the knowledge of TPL deviation as an addition of medistinal lymphadenopathy in Hodgkin's disease (Martin, 1967; Witten etal., 1965) we have added two more conditions, i.e. carcinoma of the oesophagus and testicular turnouts producing TPL changes due to involvement of the mediastinum. Peri-oesophageal spread of carcinoma of the oesophagus into the posterior mediastinum though considered:rare (Daniel e t at., 1960; Frazer, 1970) does OCcur and i s thought to be responsible for unsatisfactm3r response to all methods of treat, ment. When the tumour spreads in the mediastinum in a plane anterior to the spine, paraspinal masses are seen due to changes in pleuro-oesophageat interface but without any change in the TPL. However, when the involvement i of the mediastinum is gross the posteromedial'b0rder of the lung is affected and there is alteration of the TPU It can, therefore, be reasoa' ably assumed" 'that TPL deviation indicates fairly advanced disease. Detectioia ~of metastatic spread of testicula~ tumours into the abdominal and mediastinal lympt~ nodes is of gFeat importance in staging the disease and subsequent decision of the extent of radiation treatment.:,All malignant tumours of the testis are characterised by early metastasis into lymph nodeS, First to be involved are the upper lumbar, then the epigastric or paraortic and then the disease spreads •
Fig. 13 - TPL deviation in a case of axillary lymphosarcoma metastasising into the extradural space. The patient developed paraplegia_ There is no vertebral lesion.
The distance of the TPL measured from the bodies of vertebrae varies from 6 to 8 m m in individuals below the age of 40 years and 6 to 15 mm above the age of 40 years. Figures given for the second category of individuals by Doyle et al. (1961) were 6 - 1 9 r a m . In elderly individuals the descending thoracic aorta tends to swing around and unfold; the TPL follows a similar outward convex course. In infants and young children~ the TPL and sometimes even the descending aorta are hardly discernible because of the small aorta and its prespinal location and less development of the posteromedial border of the left lung. In some individuals the aorta is completely prespinal and there is no aortic and no TPL shadow. There are a few individuals where there is an aortic shadow but no TPL shadow, In such cases though the aorta is in a plane anterior to the vertebral bodies it projects beyond the lateral vertebral border. Airight-sided aorta is associated with a right-sided TPL. It is concluded from these observations that anatomical and physiological variations in descending aorta are closely reflected on the course and direction of the TPL. In systemic hypertension where there is aortic unfolding, the TPL also unfolds and the degree of TPL deviation has a fair degree of linear correlation with severity and duration of hypertension• The TPL deviation may be accepted as a new and subsidiary radiographic sign of systemic hypertension especially in young patients. In young patients in whom hypertension is discovered incidentally, the degree of TPL
•
.
.
"qtlOll
THE THORACIC PARASPINAL LINE aloog the prevertebral chain to the posterior mediastinal lymph nodes. Some of the lymphatics from the testis, however, reach the mediastinum directly, ~,ithout being intercepted by abdominal lymph ~0des. Thus it can be assumed that mediastinal h nodes may be involved without involvement igastric lymph nodes. Twelve cases showing TPL deviation indicating mediastinal involvement out of 30 cases of testicular tumour is a very high incidence and the need for search for this involvement in all caseS is stressed. In the absence of other evidence of intrathoracic disease and palpable abdominal lymph nodes, the TPL deviation seen on the dorsal spine radiograph assumes great clinical significance as in sach cases the mediastinum which otherwise would not be considered fo~ inclusion in the radiation treatment will be included in the radiation field and enhance the therapeutic efficacy of treatment. Lyrnphography, mediastinography, mediastinal biopsy and azygos venography are other methods to assess mediastinal involvement but they are technically difficult and not without risk to the patient and hence not employed by us in routine clinical practice. Extradural granulomas or abscesses of the thoracic spinal canal usually present with paraparesis or paraplegia. Results of early decompression are good. Decompression if delayed may result in irreversible damage to the spinal cord; this is especially true of extradural abscesses. Various parameters of diagnosis Of spinal compression is such cases are rise in CSF proteins and finding of myelographic block. There is often no radiographic evidence of contiguous bone involvement. Presence of TPL deviation corresponding to clinical and myelographic block found in the present series is an interesting new finding. It is postulated that extradural pathological process in the thoracic spinal canal which is not a watertight compartment extends outside through the intervertebral foramina into the thoracic paravertebral region and displaces the posteromedial border of left lung resulting in TPL deviation. It is surprising that authors who have reported on the subject have no mention of TPL devia(ion. It is probable that there was no special awareness to look for this sign. Similarly, metastatic extradural masses produce lateral deviation of TPL. Acknowledgements. The author thanks Dr K. N. Udupa, FACS, FRCS, FAMS, Director, Institute of Medical Sciences,
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for his kind permission to publish this paper. His thanks are also due to Shri D. K. Mathur for photography and Shri Suraj Lal for secretarial assistance.
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