Abstract
Retinal migraine is a rare and poorly understood migraine variant, initially described by Galezowski (1) in 1882 as ‘ophthalmic megrim’. This entity was included in the 1988 International Classification of Headache Disorders (ICHD) of the International Headache Society (IHS) (2). In essence, retinal migraine was defined by at least two attacks of fully reversible monocular scotoma or blindness lasting less than 60 min associated with headache. Criteria were revised in the 2004 edition of ICHD-2 to include both positive and/or negative monocular visual phenomena, no longer limited to 60 min (3). Visual features had to be transient in nature. In addition, the headache had to fulfil criteria for migraine without aura. In rare past reports, visual impairment endured from hours to days (4–8). Herein, we report two patients with unusually prolonged monocular blindness attributable to attacks of migraine. In both of these cases the visual loss sometimes lasted weeks but was fully reversible.
Case reports
Patient 1
This woman presented to the Montefiore Headache Unit in November 1994 at age 30 and was followed for 7 years. Her headaches began at age 28 after a motor vehicle accident; she struck the left side of her head but did not lose consciousness. She described two types of headache. The more severe type met ICHD-2 criteria for migraine with aura; it was associated with loss of peripheral vision in both eyes. On rare occasions vertical diplopia was noted during the headache and once syncope occurred. Subcutaneous sumatriptan aborted the attacks.
The second headache type was a mild bifrontal headache which occurred on a near daily basis, sometimes associated with jabs of pain scattered over different areas of the head. There were no associated symptoms. There was no family history of headache. The general and neurological examinations were normal. Magnetic resonance imaging (MRI) of the head and orbits was normal. Laboratory studies were non-contributory. These headaches disappeared after 4 years.
In April 1998 she awakened with blurring of vision in the left eye unassociated with headache. This monocular feature fully cleared after 3 weeks with rare, transient clearing of vision lasting 1–2 h during the 3-week period. MRIs of the head and orbits with gadolinium were normal, as was an extensive evaluation for hypercoagulability and autoimmune diseases.
In August of 1998, she awakened with blurring of vision in the left eye and migraine headache with her typical conventional aura (loss of peripheral vision in both eyes). Three weeks later an arcuate defect was noted within the temporal and nasal superior fields of the left eye (Fig. 1). Repeat visual field examination after another 3 weeks found complete resolution. During office visits over the years, left monocular visual field defects were noted on examination by confrontation on several occasions. Left monocular visual field defects on examination were not in consistent locations, but most often were predominant in one quadrant.
Arcuate defect in the left eye 3 weeks after migraine with conventional visual aura. The defect had completely cleared at the time of the second examination, 3 weeks later.
Since the summer of 1998 through last follow-up in 2002, she had four to seven migraine headaches per month, often with a typical visual aura. Some degree of a left monocular visual field defect was associated with almost every migraine headache. About once every 3 months, usually associated with a severe headache, a left monocular visual field defect of severe blurring or total blindness would last for hours or 2 days after the headache. Rarely, the visual defect lasted 1–2 weeks, always with complete resolution. Therapeutic trials included many calcium channel blockers, antidepressants, anti-epileptic drugs and β-blockers, all without benefit. The last medical regimen included atenolol 100 mg per day, imipramine 25 mg per day, and morphine immediate-release 15 mg for the acute attacks.
Patient 2
This woman was first seen at the Montefiore Headache Unit in 1994 at age 41 and has been followed for 10 years. She began to experience headaches at age 34. The headaches fulfilled the ICHD-2 criteria for migraine with aura. For 30 min before the headache she would experience blurring in the periphery of her visual fields (tunnel vision) and colours appeared more intense. There might be flashing white lights in wavy shapes or black dots. At age 43 paraesthesias of the right hand and face sometimes accompanied the headache and persisted for 3 days after the headache. Examination during an attack revealed hypalgesia and hypaesthesia of these parts.
On one occasion during the first year of headaches she experienced a bout of syncope followed by her typical headache, transient vertical diplopia and later numbness of the right hand. The headache and numbness persisted for 5 days. Several days later the headache recurred with numbness and weakness of the right upper and lower extremities and right side of the face, all clearing after 36 h. About 1 year after the onset of the above headaches, a low-grade continuous ache mainly in the right supraorbital area was present. The chronic daily headaches disappeared after several years. Three bouts of cluster headache occurred at ages 42, 43 and 44. (The latter were right orbital, throbbing, incapacitating, 45 min in duration, awakening the patient from sleep every night for 3 weeks in a row. Redness, tearing and ptosis of the right eye with right nasal discharge accompanied this headache.) Jabs and jolts of head pain were occasionally noted.
Her mother and maternal grandmother had migraine. General and neurological examinations were normal. Routine haematological tests, computed tomography of the head, MRI of the brain, EEG and lumbar puncture were normal.
At age 44 and unrelated to headaches, the patient experienced a scotoma affecting the right eye recurring every day for 3 weeks, lasting 15 min to 4 h. Visual field examination 2 days after onset and during the symptom revealed a defect in the superior temporal quadrant of the right eye; the visual field for the left eye was normal. An MRI of the brain 6 days after onset was normal. Four months later the right visual field defect began as a regular antecedent of her migraine attacks.
During the next 4 years, migraine with aura recurred from one to three times per week. The superior temporal visual field defect in the right eye was frequently associated. She described the defect ‘like black paint slowly dripping down’ the corner of her right eye. Some years it occurred with every fourth headache; during 1 year it occurred with almost every headache. The defect would usually disappear when the headache cleared, 4 h to 1 day in duration, but on some occasions the visual field defect would last for hours or days after the headache and on at least two occasions the defect persisted for 1 and 2 weeks (Fig. 2). The defect was always fully reversible, as evidenced by normal visual fields taken 5 weeks after onset.
Superior temporal quadrantic defect in the right eye 2 weeks after migraine with conventional visual aura. The defect began ‘like black paint slowly dripping down’. This defect completely cleared with repeat perimetry 3 weeks later.
Treatment with triptans or ergots was discontinued after confirmation of monocular visual field defects and opioids were substituted. Prophylactic medications included several β-blockers, many calcium channel blockers, antidepressants (including MAO inhibitors), anti-epileptic drugs, antiserotonin agents, and others (e.g. riboflavin, feverfew, magnesium, lithium, omega fish oil, oestradiol). Consistent benefit did not occur.
When last seen (late 2004) migraine recurred two to three times per week lasting 6 h. Tunnel vision affecting both eyes or right upper quadrant defect preceded the headache by 30–60 min and persisted through the headache. Chronic daily low-grade headache no longer occurred. The most recent medical regimen included daily verapamil 240 mg, amitriptyline 30 mg, tizanidine 8 mg and oxycodone IR 5 mg for severe attacks and a butalbital compound for moderate attacks.
Discussion
We present two patients with complex headache histories. Both patients experienced migraine accompanied by brief conventional visual auras as well as transient monocular visual field defects, usually persisting for the duration of the headache but sometimes prolonged. Both patients had years of chronic daily headaches, rare bouts of basilar-type migraine and primary stabbing headache. Patient 2 also had three bouts of cluster headache. Patient 1 had many attacks with transient monocular visual defects accompanying migraine headache. The monocular defects usually cleared with the headache after 4–24 h but sometimes lasted for days after the headache, and rarely for 1 and 2 weeks. Patient 2 experienced transient monocular visual defects heralding almost every migraine, usually clearing by the end of the headache. The visual defect sometimes persisted up to 48 h after the headache, and on rare occasions persisted for weeks.
These two patients meet ICHD-2 criteria for retinal migraine except that they experienced migraine with typical aura rather than migraine without aura. The criterion of migraine with aura for retinal migraine was changed from non-specific ‘headache’ in ICHD-1 to ‘migraine without aura’ in ICHD-2. We assume that our patients would meet this criterion but recommend clarification in the next revision of ICHD. As our cases demonstrate, patients may have visual aura of both cortical and anterior visual pathway origin. The monocular visual field defects in these patients (Figs 1 and 2) are not necessarily of retinal origin. The affected site could be the optic nerve or choroid. For this reason, ‘monocular migraine’ would be a more appropriate term than retinal migraine. Both cases also support the change in the ICHD-2 classification broadening the definition of retinal migraine to include monocular aura durations of more than 1 h.
There have been other patients with migraine and monocular aura of duration greater than 1 h. Fisher (4) reported a 35-year-old man who had migraine with sensory and aphasic auras associated with recurrent spells of transient monocular visual loss, lasting from seconds to minutes. Following a headache that was more severe than usual, the patient developed an ecchymosis below the right eyebrow and experienced prolonged but fully reversible monocular visual loss lasting 12 h. In the same monograph, Fisher reported a 49-year-old woman with four episodes of transient left monocular blindness in association with attacks of migraine. In three of these attacks the loss of vision in one eye lasted several hours. Fujino et al. (5) reported a 31-year-old Japanese male with migraine (type unstated) in which an attack of unilateral visual loss lasted 7.5 h. James et al. (6) reported a 36-year-old man with a history of migraine accompanied by either a conventional visual, olfactory or gustatory aura. In addition to these symptoms, the patient also experienced monocular visual defects for up to 2 days in either eye with the headache. Katz (7) reported a 29-year-old male migraineur with typical visual aura associated with repeated attacks of reversible monocular visual loss, the longest of which lasted 12 h. Sullivan-Mee et al. (8) reported a 34-year-old female migraineur without a conventional visual aura who presented with a persistent monocular visual field defect of at least 1 month related to an attack of migraine.
The mechanisms of prolonged but fully reversible monocular visual loss as a migraine aura are uncertain. Prolonged aura (IHS 2004 terminology: persistent aura without infarction) may occur as a feature of homonymous or binocular visual aura (3). Cortical neuronal hyperactivity followed by spreading depression is considered to be the mechanism of the typical migraine aura and persistence of this phenomenon is the most likely cause of prolonged aura without infarction (9). Changes in perfusion have been demonstrated in patients with prolonged aura but ischaemic thresholds were not attained (10–13). Why depressed neuronal activity is prolonged is not understood, but vasospasm and associated ischaemia does not appear to be the mechanism. Spreading depression of retinal neurons has been noted in the retina of the chicken (14). We believe the long duration of monocular defects associated with migraine headache, as noted in the cases presented, may have the same mechanism as that in the cerebral cortex in migraineurs who have persistent aura without infarction.