I traumi cervicali

Abstract

Injury to the cervical spinal cord is a major health problem owing to its frequency and to the often devastating sequelae of serious trauma with respect to long-term disability for the patient.

Cervical injuries are often reported in association with head trauma and cervical spinal cord injury appears to be a major contributing factor in acute death secondary to traffic accidents producing severe head injuries.

A high incidence of neurological deficits is reported in cervical spinal trauma, but cervical injuries can escape detection in the acute phase if clinically silent or in patients unconscious from to head trauma.

The most important predisposing factor in the concomitant occurrence of head and neck trauma is transmission of forces through the cranial vault to the cervical spine. Other underlying cervical spine diseases, either congenital or developmental, may also predispose to the development of cervical injuries.

The spine includes bony-ligamentous structures and nervous structures. The bony-ligamentous involucre is anatomically predisposed to perform three major tasks: 1) maintenance of spinal statics; 2) mobilization in the three anatomic planes and 3) protection of nervous and vascular structures inside the spinal canal.

The cervical spine is subjected to varying forces of flexion, flexion-rotation, extension and vertical compression which result in damage to the different components of the spine when they are applied beyond physiological limits. Biomechanical considerations of the different motion patterns that occur in the cervical spine are essential to understand the contribution of mechanical stresses to the development of specific spinal injuries.

This chapter tackles the problem of a logical management of cervical spinal trauma based on clinical presentation to:

a) identify the preferential diagnostic modality to investigate that type of injury (conventional X-Ray, Computed Tomography, Magnetic Resonance);

b) interpret images, indipendently from the diagnostic modality utilized, considering the cause-effect relation between the traumatic force and the anatomic-functional structures involved by the trauma.

The clinical picture may include pain, movement limitations and/or radiculo-myelopathy. Cerebral neurologic deficits can be the consequence of traumatic damage to the carotid and vertebral artery system in the neck. Evaluation of injury instability is one of the main goals of radiographic investigation. One classifies bony instability which is temporary, as opposed to disco-ligamentous instability which is permanent and usually requires surgical stabilization, and mixed instability.

Conventional lateral and antero-posterior radiographs should be initially performed in patients with cervical trauma and in polytrauma and comatous patients who are difficult to assess clinically.

They effectively screen vertebral fractures, vertebral body and facet dislocations and pre-vertebral soft tissue swelling. However, ligament disruption and instability can be underestimated by a normal disco-vertebral alignment. Dynamic flexion-extension views, useful to reveal such an instability, should never be performed in the acute phase particularly if fractures and neurologic deficits are present.

CT scan, in addition, has several advantages: the axial plane provides an optimal view of the size and shape of the spinal canal, bony fragments and foreign bodies within the canal are very well depicted, posterior element fractures are better visualized. A preexsisting spondylotic narrow canal is well evaluated by CT as are post-traumatic disc herniations. Widening of the apophyseal joints, suggesting disruption of facet capsules and spinal instability, is best demonstrated by CT.

However, CT has some limitations in evaluating ligament instability since it is performed in the neutral position and, in addition, it cannot visualize the medulla and its potential traumatic lesions. After the introduction of MRI, myelography and CT-myelography are no longer used to investigate cervical spine lesions involving cord and nerve roots. MRI should be performed in every patient presenting with neurologic deficits.

The usefulness of MR is in detecting extradural compressive lesions like disc herniation and haematomas that need to be decompressed surgically. MRI can also evaluate ligamentous integrity and disk rupture. Bony fractures are revealed by MRI either by signal or morphologic alterations of vertebral bodies, but thin, linear fractures are less well identified than with CT.

One of the main advantages of MRI is the direct identification of intrinsic cord pathology such as cord contusion and haemorrhage. Cord haemorrhage seems to be predictive of a complete lesion and of poor outcome. Therefore MRI is proposed to assess the prognosis of traumatic cord lesions, the best time for imaging ranging between 24 and 72 hours after injury.