Trochlear Headache: A Rare, Specific 'Eye-strain' Headache
Abstract & Commentary
By Dara Jamieson, MD
Associate Professor of Clinical Neurology, Weill Cornell
Medical College
Dr. Jamieson reports no financial relationships relevant to this field of study.
Synopsis: Trochlear headaches should be considered
in patients with new onset, constant, unilateral eye pain, especially when the pain is aggravated by eye movement.
Source: Smith JH, et al. Clinical features and long-term prognosis of trochlear headaches. Eur J Neurol 2014;21:577-585.
The trochlear nerve (cranial nerve iv) innervates a single muscle: the superior oblique muscle that depresses and adducts the eye. The tendon of the trochlear nerve sits in the trochlea, a saddle or pulley-like cartilaginous structure that is located in the superomedial orbit. Inflammation of the trochlea, trochleitis, produces swelling and tenderness, presenting as a unilateral periorbital pain, a headache referable to the trochlear apparatus. Trochleitis can be idiopathic or secondary to inflammatory or autoimmune connective tissue disorders. A primary trochlear headache, not associated with inflammation, has also been described. Smith et al described 25 cases of this rare trochlear headache disorder, compiled retrospectively over 5 years (2007-2012) after diagnosis at the Mayo Clinic. The diagnosis of trochlear headache was not recognized by the referring neurologist or ophthalmologist, who reported the diagnoses of chronic migraine (n = 13), new daily persistent headache (n = 5), no diagnosis (n = 4), hemicrania continua (n = 2), and atypical facial pain (n = 1). Patients were generally female (n = 20, 80%) with a median age at diagnosis of 46 years (range 18-77). Patients had a median time from symptom onset to diagnosis of 6.7 months (range of 2 weeks to 10 years). Characteristically, the headache was a continuous, dull or achy, moderate-to-severe, periorbital (medial eyebrow, orbit, or forehead) pain that was associated with photophobia and binocular diplopia. The pain was aggravated by eye movement or reading. Almost half of individuals with trochleitis (clinically apparent trochlear edema) had an identified secondary mechanism, such as Behcet’s syndrome, granulomatosis polyangiitis, lymphoma, or Tolosa-Hunt syndrome. Imaging of the trochlea tendon by contrast magnetic resonance imaging or computed tomography study of the orbits was diagnostic in all but one patient. Injection of dexamethasone/lidocaine near the trochlea usually provided symptomatic relief. At a median follow-up of 34 months (range 0-68 months), 10/25 (40%) of the cohort of patients with trochlear headache had experienced complete remission. The authors concluded that the diagnosis of a trochlear headache should be considered in patients presenting with a new daily eye pain that is aggravated by eye movements, especially while reading.
Commentary
Unilateral periorbital pain is found with multiple headache types, but generally that pain localization is associated with migraine headaches, the most common headache type found in a neurological practice. The migraine-accompanying symptoms, as well as pain that generally switches sides or expands bilaterally, aid in making a migraine diagnosis. A less common cause of unilateral, generally side-locked, pain is cluster headaches and other trigeminal autonomic cephalgias, but these headaches are characterized by an array of distinctive dysautonomic symptoms. The International Classification of Headache Disorders, 3rd edition (beta version), published by the Headache Classification Committee of the International Headache Society (IHS), catalogues what may be misperceived as an amorphous complaint into precisely defined headache syndromes. Headache attributed to trochleitis is defined by the ICHD-3 beta as "Headache, usually frontal and/or periorbital in location, with or without eye pain, caused by peritrochlear inflammation. It is often exacerbated by downward movements of the eye."1 Trochleitis can also trigger an episode of migraine ipsilateral to the periorbital pain. Although patients often incorrectly attribute headaches to excess use of their eyes, trochlear headaches are distinctly exacerbated by eye movement or reading. Neurologists will rarely encounter a patient with trochlear headache; unless the diagnosis is considered and review of brain imaging is focused on the area of interest, the opportunity for focused treatment of trochlear headache may be lost.
Reference
- Headache Classification Committee of the International Headache Society (IHS) The International Classification of Headache Disorders, 3rd edition (beta version). Cephalalgia 2013;33:629-808.
