Fig. 5

a Axial image of MDCTA of sharp (non-projectile) penetrating injury to the left zone 3. The implement bisected the left carotid sheath just below the skull base with the wound track (blue arrow) splaying the internal carotid artery (red arrowhead) from the internal jugular vein (blue arrowhead) but not causing any radiologically evident vascular injury. The patient exhibited clinical signs of Collet-Sicard syndrome—palsies of cranial nerves IX, X, XI and XII. The MDCTA demonstrates flattening of the left lateral pharyngeal recess (red arrow) compared with the contralateral side as a result of a combination of haematoma and superior pharyngeal constrictor paresis (the motor supply of the superior pharyngeal constrictor is through the motor component of the pharyngeal plexus derived from the cranial part of the accessory [XI] nerve). There is a nasogastric (NG) tube in situ. b Axial image of MDCTA of the same patient as in a showing evidence of left hypoglossal nerve palsy—there is flaccid prolapse of the tongue base (blue arrow) and deviation of the median fatty raphe to the ipsilateral side (blue arrowhead) and reduced calibre of the left glossopharyngeal sulcus (red arrow). The NG tube is noted in situ. c Axial image of MDCTA of same patient as in a and b. There is subtle medialisation of the left true vocal cord (blue arrow) consistent with a left vagus nerve palsy confirmed on flexible nasoendoscopy; this is one of the components of Collet-Sicard syndrome. The NG tube is evident in situ. d Coronal reformat of the same patient as in a, b and c. A metal fragment of the implement used to inflict the penetrating injury remains lodged in the left prevertebral soft tissues (blue arrow) having bisected the left carotid sheath and injured the adjacent cranial nerves