Table 1 Clinical, primary and secondary findings of CN pathology
Symptoms/signs that trigger search pattern for CN pathology | Which CN to suspect? | What to look for and where to look for it on PET/CT? | |||
|---|---|---|---|---|---|
Primary Sign | Secondary Signs | ||||
Abnormality along course of CN | Abnormal skull base foramen/ bone | Muscle atrophy | Over compensation | ||
Anosmia | CN I (Olfactory) | Roof of nose and anterior cranial fossa | Cribriform plate of ethmoid | -- | -- |
Visual loss | CN II (Optic) | Orbit, suprasellar cistern | Optic canal | -- | -- |
Diplopia | CN III (Oculomotor) | Cavernous sinus | Superior orbital fissure (SOF) | Extraocular muscles (except superior oblique and lateral rectus muscles) | -- |
Vertical diplopia | CN IV (Trochlear) | Cavernous sinus | SOF | Superior oblique | -- |
Trigeminal Neuralgia | CN V (Trigeminal, main trunk) | Pons, prepontine cistern, Meckel's cave. | -- | -- | -- |
Paresthesia over forehead and eye | CN V1 (Ophthalmic division) | Cavernous sinus | SOF | -- | -- |
Paresthesia over cheek | CN V2 (Maxillary division) | Cavernous sinus, cheek | Foramen rotundum, pterygopalatine fossa and infraorbital canal /foramen | -- | -- |
Paresthesia over chin, trismus | CN V3 (Mandibular division) | Masticator space | Foramen ovale, mandibular canal and mental foramen | -- | -- |
Lateral gaze diplopia | CN VI( Abducens) | Cavernous sinus, clivus | SOF | Lateral rectus | Ipsilateral Medial rectus |
Facial palsy | CN VII (Facial) | Cerebellopontine angle , parotid space | Petrous bone, internal auditory canal (IAC), and stylomastoid foramen | -- | -- |
Hearing loss/ imbalance | CN VIII (Vestibulocochlear) | Cerebellopontine angle | Petrous bone and IAC | -- | -- |
Hoarseness | CN X (Vagus nerve, recurrent laryngeal branch) | Carotid space, tracheoesophageal grooves, around aortic root | Jugular foramen (JF) | Ipsilateral vocal cord | Contralateral vocal cord |
Shoulder drooping | CN XI (Spinal accessory) | Carotid space | JF, foramen magnum | Sternomastoid and trapezius muscles | -- |
Dysarthria and dysphagia | CN XII (Hypoglossal nerve) | occipital condyles , Carotid space, base of tongue | JF, Hypoglossal canal | Ipsilateral hemitongue | Contralateral hemitounge |