The trigeminal nerve is the largest cranial nerve. It is comprised of large sensory root and small motor root at the level of pons. The trigeminal ganglion lies in Meckel’s cave. The ophthalmic branch comes out through the superior orbital fissure, maxillary through foramen rotundum and mandibular through foramen ovale. It supplies sensation for the face and mouth and muscles of mastication (tensor tympani, tensor veli palatini, mylohyoid and anterior belly of digastric).

Compression of the trigeminal nerve (mostly vascular – superior cerebellar artery) near its origin at the brainstem. The pressure causes demyelinating changes leading to abnormal depolarisation resulting in ectopic impulses. Trigeminal neuralgia may be associated with middle and posterior cranial fossa tumours. Cerebellopontine angle tumours may cause TN. Multiple sclerosis increases the risk of TN, and mostly the pain is bilateral and patients are young.

Unilateral short-lived, strong sharp shooting pain which may involve one or more branches of the trigeminal nerve. The pain is typically of sharp shooting, lancinating type. It is like an electric shock and is triggered by eating, washing, shaving and cold and warmth. The pain occurs in attacks and lasts from few seconds to few minutes. The attack is followed by a refractory period. Most of the attacks are unilateral. Patients with severe pain may have detectable sensory loss.