An Anomolousincidence of a Cervical Rib-A Radiographic Case Report
Vinodhini P., Sendil Kumar, Mamatha H., Antony Sylvan D’souza
1. PG Student, Department of Anatomy, Kasturba Medical College, Manipal-576104, Karnataka, India. 2. Assistant Professor, Department of Radiology, Kasturba Medical College, Manipal-576104, Karnataka, India. 3. Assistant Professor, Department of Anatomy, Kasturba Medical College, Manipal-576104, Karnataka, India. 4.Professor and HEAD Department of Anatomy Kasturba Medical College, Manipal-576104, Karnataka, India.
Correspondence Address :
Dr. Mamatha H,
Department of Anatomy, Kasturba Medical College,
Manipal University, Manipal-576104, Karnataka, India.
The 7?sup?th#sup# cervical vertebra or vertebra prominence is visible and palpable for its long spinous process at the lower end of the nuchal furrow. The costal lamella is thin and partially deficient or may separate as a cervical rib. During the routine radiologic interpretation of a chest X-ray, in the of Department of Radiology, Kasturba Medical College, Manipal, India, we observed a case of right cervical rib, in a 30 years old woman. The patient came to the OPD with the complaints of swelling along the arms, pain, feeling of pins and needles in her affected right arm. The cervical rib is a supernumerary rib arising from a cervical vertebra, an elongation of the transverse process of the seventh cervical vertebra. However, cervical ribs are accessory or additional ribs that are permanent dysmorphological structures, forms an important cause for neurovascular compression and consequent muscular and cutaneous symptoms at the thoracic inlet and beyond into the upper extremity. Accessory ribs are permanent structures in contrast to ossification sites that disappear postnatally, probably becoming part of the lateral transverse vertebral processes.
|Keywords : Cervical rib, Thoracic outlet syndrome, Neurovascular disturbances|
The 7th cervical vertebra or vertebra prominence is visible and palpable for its long spinous process at the lower end of the nuchal furrow. The ribs are 12 pairs of elastic arches that articulate posteriorly with the vertebral column.Their number may be increased by cervical or lumbarribsor reduced by the absence of the twelfth pair. A cervical rib is the costal element of the seventh cervical vertebra, often it has an head, neck and tubercle. When a shaft is present, it is of variable length, and extends anterolaterally into the posterior triangle of the neck, where it may end freely or join the first rib or costal cartilage. A cervical rib can be partly fibrous,being its effects unrelated to the size of its osseous part (1).
It is related to first thoracic rib, lower trunk of the brachial plexus and Subclavian vessels which are superior and prone to suffer compression in a narrow angle between rib and Scalenus anterior. Hence cervical ribs may first be revealed bynervous and vascular symptoms, particularly those caused by pressure on the eighth cervical and first thoracic spinal nerves (2),(3).
During the routine radiologic interpretation of a chest X-ray (Table/Fig 1), in the of Department of Radiology, Kasturba Medical College, Manipal, India, we observed a case of right cervical rib, in a 30 year old woman. The patient came to the OPD with the complaints of swelling along the arms, pain, feeling of pins and needles in her right arm.
The cervical rib, a supernumerary rib, an elongation of the transverse process of the seventh cervical vertebra are permanent dysmorphological structures, induced by xenobioticor maternal stress, forms an important cause for neurovascular compression and consequent muscular and cutaneous symptoms (3). Accessory ribs are permanent structures in contrast to ossification site that disappear postnatally, probably becoming part of the lateral transverse vertebral processes.cervical ribs are normally present in crocodiles (4).
The correlation of symptoms must be due to mutual influences ofthe notochord, neural tube, neural crest, andsomites during the time of somite formation. An incidence of 25% cervicalribs was found alongwith childhood carcinomas. HOX genes play an important role in the patterning of the axial skeleton in all vertebrateclasses. In mammals Hox genes are involved inpatterning of the skeletal axis and in its proliferation, whereas the neuronal problemsare a direct consequence of the aberrations in the regulation of Hox genes. During embryological development, each segment contains spinal nerve, meroblastic tissue which will form a rib or the costal element of a vertebra. An extensive studies of adults found cervical ribs to be more common in females and on the right side (5).
In the cervical and thelumbarregions the developing nerve takes precedence over the rib so that developmentof a rib at these levels is prevented. The costal element of the 7th cervical vertebra was normally present as a separate entity in the cervical region in the fetus,which disappears after birth by becoming incorporated by synostosis into thetransverse process of the associated vertebra (5),(6).
The embryonic nerve trunks arelargerin proportion to the vertebra and ribs. The obliquely running nerves impede the growthof the ribs, therefore discouraging them to form vertebral processes. Ribs are normally present in the fetus in articulation with vertebrae above the eighth, and after birth they are present only astransverse processes of the cervicalvertebrae. The extent of growth of a cervical rib is determined by the resistanceof the nerve in its path. The complete cervical rib extends forward and downwardbetween the Scalenus anterior and Scalenusmedius muscles to meet the costal cartilage of the first rib (7),(8).
The effect of a cervical rib is to raise the artery in the neck, thus sharpening the smooth curve, arching over the first rib. Any drag on the arm will angulate the artery over a rigid structure, and a common complaint of these patients is inability to carry a heavy package on the affected side. The end result may be ischaemic contracture of forearm and hand, or a major amputation, following occlusion of the main vascular channels by embolism or thrombosis (9).
The lowest trunk of the brachial plexus is intimately related to a cervical rib more often than is the subclavian artery, suggested that vascular symptoms associated with such a rib might be due to paralysis of the sympathetic fibers running in this trunk (9),(10).
In our present case,the presence of a right cervical rib, presume to cause the right Sub clavian vascular compression know as Thoracic Outlet Syndrome: [TOS]. Such an Arterial TOS would have been the result of emboli arising from subclavian artery stenosis or aneurysms. Symptoms of digital ischemia, claudication, pallor, coldness, paresthesia, and pain in the hand but seldom in the shoulder and the neck are analyzed during outpatient medical examination and X-rays almost disclose a cervical rib of osseous type with a round end. Our findings coincide with the cases having complications due to arterial emboli arising either from mural thrombus in a Sub clavian artery aneurysm or from thrombus forming just distal to Sub clavian arterystenosis. TOS is the most difficult-to-treat entrapment neuropathy encountered by neurosurgeons. Surgical intervention is indicated for patients with vascular and true neurogenic symptoms (11),(12).
The etio pathogenesis can be explained by thepressure and functional disturbances on the neurovascular bundle in thesupraclavicular fossa or in the costoclavicular space. Such pressure maybe caused by tightening, fibrosis or hypertrophyof the anterior scalene muscle, the pressure ofa cervical rib, narrowing of the costoclavicularspace.The pain in the shoulder and the arm was occasionally relieved by elevating the shoulder on a pillow (11),(12).
An attempt being made to resect the rib along with thedivision of intervening bands, the cervical trunks and the neurovascular bundles are repositioned in order to escape further entrapment.
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