Nasociliary Nerve Block for Charlin Syndrome

Indications and Clinical Considerations

Nasociliary nerve block is useful in diagnosing and treating Charlin syndrome, which is also known as nasociliary neuralgia . Although, as with most headache syndromes, the exact cause of the pain from Charlin syndrome is unknown, the pathogenesis of this uncommon source of head and face pain is thought to be the dysfunction of the nasociliary ganglion in a manner analogous to the dysfunction of the sphenopalatine ganglion, which is thought to be the source of cluster headaches. The presenting symptom of patients with Charlin syndrome is severe paroxysms of ocular or retro-orbital pain that radiates into the ipsilateral forehead, nose, and maxillary region. This pain is associated with voluminous ipsilateral rhinorrhea and congestion of the nasal mucosa as well as significant inflammation of the affected eye ( Fig. 13.1 ). The pain of Charlin syndrome has a rapid onset to peak, with attacks lasting 45 to 60 minutes. In some patients, these attacks can be triggered by sensory stimulation of the affected areas. Although in many ways similar to a cluster headache (e.g., retro-orbital location of pain, profuse unilateral rhinorrhea, rapid onset to peak, short duration of attacks), there are many dissimilarities. Unlike in cluster headaches, alcohol does not seem to trigger Charlin syndrome attacks, and the seasonal and chronobiologic patterns so characteristic of cluster headaches appear to be absent ( Table 13.1 ). Furthermore, blockade of the sphenopalatine ganglion, which is so effective in the treatment of cluster headaches, is of little value in the treatment of Charlin syndrome, whereas patients with Charlin syndrome uniformly respond to daily nasociliary nerve blocks with local anesthetic, as described later.