Diagnosis

In one approach to patients with visual hallucinations and illusions, the general categories (see Table 12.1 ) should be considered first. Then, the patient’s description of the visual phenomena is often very suggestive of a particular cause. Finally, the history and examination give the clinical setting and frequently supply clues to establish the proper diagnosis. For example, in a patient with a normal examination, a crescent of pulsating zig-zag lines seen in visual periphery, followed by a headache with nausea and vomiting, is most likely the result of a migraine. Brief episodes of flashing lights followed by loss of consciousness are more consistent with epilepsy. An individual with dense cataracts who complains of seeing people or objects that are not there may suffer from sensory deprivation associated with bilateral visual loss. This patient most likely has release hallucinations.

Treatment Overview

In hallucinations due to migraine or epilepsy, the treatment is directed at the underlying disorder. In psychiatric and neurodegenerative disorders, treatment of the primary disorder is also important, but the addition of a neuroleptic is often required in these two conditions. In general, hallucinations associated with illicit or prescription drug use should be treated by removing the offending agent. In contrast, release visual hallucinations are very difficult to treat. Rarely affected patients require low-dose neuroleptics, but most often patient reassurance is the best management.

Fortification Spectra and Scintillating Scotomas

A visual aura consisting of fortification spectra or a scintillating scotoma, followed by a headache, is almost pathognomonic of migraine. The fortification spectra phenomenon, the most common visual aura, is characterized by an arc of jagged, serrated, or zig-zag lines ( Fig. 12.1 ). Patients often relate that the lines, also termed teichopsia, shimmer, scintillate, vibrate, flicker, or pulse at 3–30 Hz. The term fortification refers to the similarity of the visual phenomena with early European military fortifications. The term spectra is used because many patients will describe colored jagged edges. The shimmering aspect gives the appearance of light reflecting off of small prisms and produces the various colors of a rainbow.

Characteristic buildup of a migrainous scintillating scotoma experienced by one of the authors while playing golf. A . Suddenly, while he was “looking at the golf ball and about to putt,” he noticed a small pulsating object in the upper right quadrant of both eyes. B . One minute later, it became more obvious to him that the object was gradually enlarging and the border of it consisted of small, jagged, and shimmering yellow, blue, green, and red prisms which flickered and pulsed at high frequency. Toward the center, there was an area of blurry, but not absent, vision (as if looking through water). C . Ten minutes later the visual disturbance continued to enlarge within the right upper homonymous quadrant. D . The blurry area and border of prisms gradually enlarged and crossed the vertical and horizontal meridians. Eventually it consumed the entire visual field then disintegrated at its borders and within the blurry center (not shown). Its resolution was followed 1 hour later by a holocephalic headache accompanied by nausea.

In addition to the typical appearance, the “buildup” or “march” of the fortification spectra is also highly characteristic ( Fig. 12.1 ). Patients usually notice the visual phenomenon paracentrally, and the open part of the arc of the fortification spectra faces centrally. Often vision within the arc is scotomatous or defective, and patients will describe this area as gray, cloudy, blurry, or water-like. The combination of the positive fortification spectra on the outside and the negative area in the middle is termed a scintillating scotoma. These are often circular, but may also be kidney-bean shaped. Over minutes, the diameter of the arc enlarges, and drifts toward the periphery, and the scotoma, when present, also enlarges. Often the entire visual field is affected, as the fortification spectra or scintillating scotoma frequently crosses the vertical and horizontal meridians. The entire sequence may take 15–20 minutes, after which the fortification spectra or scintillating scotoma break up and disappear. The phenomenon is usually homonymous but also can be monocular. However, often it is difficult for even the best observers to describe whether the phenomenon is perceived in one or both eyes.

Aura not due to migraine . Although highly suggestive of migraine, fortification spectra and scintillating scotomas may also be triggered by cerebral mass lesions such as arteriovascular malformations (AVMs), neoplasms, or abcesses, with or without seizure activity. In some instances, after the hallucination resolves, a patient with an underlying mass lesion will have a residual visual field defect. Rarely, scintillations without “buildup” also can be associated with posterior cerebral artery ischemia. There should be a low threshold for neuroimaging to rule out a structural cause in any patient with an accelerated frequency, intensity, or duration of homonymous positive visual phenomenon (particularly if they are always on the same side), or if these present late in life without a previous history of migraine.

Simple Positive Visual Phenomena in Migraine

Many patients with migraine report seeing less complex phenomena, some of which are listed in Box 12.1 . Unlike fortification spectra and scintillating scotomas, these simple hallucinations tend not to “build up.” For instance, patients may describe “dancing lights,” “shapes,” or a “flash bulb.” In some, flashes of light last only fractions of a second; however, they may migrate across the visual field ( Fig. 12.2 ). Patients with these complaints should prompt consideration of anterior visual pathway disorders of the retina and vitreous that may manifest with photopsias and phosphenes (see Entoptic Phenomena ).

Migration of a characteristic simple visual phenomena drawn and described by a migraineur. A . He wrote that in one episode, “a colored bar appeared at the center of the eye and began flashing and flickering, then moved from the center of the eye to the left. This lasted about 10 minutes. After the bar reached the side of the eye, it took the shape of an arc and continued to flicker for about 10 minutes.” B . In another episode, “when looking down on the floor, eight-pointed colorful starlike figures appeared (one at a time), flickering and bright. One of the starlike figures (depicted in drawing), appeared at the center of the eye and worked itself toward the left outside of the eye, blinking and flickering as it moved.”

Complex Visual Hallucinations in Migraine

Visual hallucinations containing complex objects such as people and animals ( zoopsia ) are unusual in migraine visual aura but are well described. Hachinski et al. described an 18-year-old girl with migraine who saw herself lying on a railroad track while a train passed over her. In her left visual field she experienced irregular multicolored scotomas. The visual hallucinations lasted 10 minutes, and the accompanying migraine headache lasted 3 hours. Out-of-body experiences, including those in which the individual views his or her own body ( autoscopy ), although more common in seizures (see later discussion), have also been reported in migraine.

When complex visual hallucinations occur in migraine, they are usually unaccompanied by auditory and abnormal thought content; however, Fuller et al. reported an exceptional 69-year-old man with migraine and complex visual and auditory hallucinations as well as paranoid delusions. He felt his wife and brother-in-law had been killed, and the “ward staff were systematically butchering other patients on the ward.” He saw “red and squirmy piranha fish on the floor of his room and would try to stamp on them, after which they would disappear.” This history would be more suggestive of a psychiatric disorder or drug use, and migraine would have to be a diagnosis of exclusion.

A unique patient with migraine auras characterized by complete achromatopsia (no perception of color), prosopagnosia (inability to recognize faces), and visual agnosia (inability to recognize objects) has also been described. These higher cortical visual disorders are discussed in Chapter 9 .

Visual Distortions and Illusions in Migraine

Metamorphopsia . Distortion of the shapes of objects may be experienced by patients with migraine (objects may appear too fat, too thin, too short, or too tall, for instance); however, metamorphopsia is a much more common complaint among patients with macular disease.

Micropsia and macropsia . In a variation of metamorphopsia, patients with migraine may complain that objects appear too small ( micropsia ) or too large ( macropsia ). In teleopsia, objects seem too far away. People may appear too small in lilliputianism. These symptoms can also be caused by seizures.

Alice in Wonderland syndrome. This condition is described here because it is classically associated with migraine; migraine is one its most commonly identified etiologies, and some affected patients without a history of migraine later develop migraine. However, the underlying cause of the Alice in Wonderland syndrome may remain uncertain in some patients.

Lippman described seven patients with classic migraine who experienced episodes of distorted body image. Each had fascinating illusions characterized by enlargement, diminution, or distortion of part of or the whole body, and each patient knew the sensations were not real. One 38-year-old woman reported attacks of feeling “about 1 foot high” accompanied by headache. Another elderly woman complained of migraine headaches preceded by the feeling of her left ear “ballooning out 6 inches or more.” His Patient 7 reported headaches accompanied by sensations of body size distortion “as if someone had drawn a vertical line separating the two halves; the right half seems to be twice the size of the left half.”

Lippman recalled that Lewis Carroll (Charles Lutwidge Dodgson), also a migraineur, had described similar hallucinations in his book, Alice in Wonderland. It has been speculated that Dodgson had experienced distortions in body image during his migraine events, and incorporated the hallucinations into the fictional story about the young girl who, during her adventures in Wonderland, shrinks and grows numerous times. Todd then coined the condition Alice in Wonderland syndrome. Rolak pointed out the similarity between original illustrations in Dodgson’s book ( Figs. 12.3 and 12.4 ) and some of the descriptions cataloged by Lippman.

This original illustration from Lewis Carroll’s “Alice in Wonderland” matches the descriptions of two of Lippmann’s patients who experienced distortions in body image, in particular, excessive height. Patient 3, a 23-year-old woman, described the following: “I experienced the sensation that my head had grown to tremendous proportions and was so light that it floated up to the ceiling, although I was sure it was still attached to my neck. I used to try to hold it down with my hands. This sensation would pass with the migraine but would leave me with a feeling that I was very tall. When walking down the street I would think I would be able to look down on the tops of others’ heads, and it was very frightening and annoying not to see as I was feeling. The sensation was so real that when I would see myself in a window or full-length mirror, it was quite a shock to realize that I was still my normal height of under five feet.” Patient 6 said “I get tired out from pulling my head down from the ceiling. My head feels like a balloon; my neck stretches and my head goes to the ceiling. I’ve been pulling it down all night long.”

(Illustration borrowed with permission from Dover Publications, Mineola, NY.)

This original illustration from Lewis Carroll’s “Alice in Wonderland” matches the descriptions of one of Lippmann’s patients who experienced distortions in body image, in particular, excessive height.

(Illustration borrowed with permission from Dover Publications, Mineola, NY.)

For unclear reasons Alice in Wonderland syndrome is more common in children. We agree with Lanska and Lanska that patients with the Alice in Wonderland syndrome can be divided into those with illusions involving their own body (intrapersonal, or pure Alice in Wonderland syndrome) versus those with illusions involving objects around them (extrapersonal, or Alice in Wonderland–like syndrome). The extrapersonal variety is more common, and micropsia and teleopsia are the most common complaints, but macropsia and metamorphopsia also occur. Some children have both intrapersonal and extrapersonal complaints. Hachinski et al. described a 6-year-old child who thought people around her were smaller than normal. Once, while playing in the snow, this same child felt that she was “unusually large” and that an ordinary snowball had become “huge and turned blue.”

Metamorphopsia, micropsia/macropsia, and Alice in Wonderland syndrome have been attributed to migrainous cortical dysfunction in the nondominant posterior parietal lobule. In contrast, single photon emission computed tomography (SPECT) imaging in one report demonstrated occipital and temporal lobe abnormalities. Frontal lobe epilepsy, encephalopathy due to infectious mononucleosis, topiramate use, and varicella infection have also been reported causes of Alice in Wonderland syndrome. In patients with Alice in Wonderland syndrome and Alice in Wonderland–like syndrome, magnetic resonance imaging (MRI) and electroencephalograph (EEG) are generally unhelpful. The condition is often self-limited, or it can persist, but nonetheless it is typically benign.

Other distortions and illusions . Migraine may also produce the perception of multiple images and should be included in the differential diagnosis of cerebral diplopia. Kosmorsky, in a report of his own acephalgic migraine, described the duplication of images within a scintillating scotoma. The double vision was present with either eye covered and did not change with either monocular or binocular viewing. Migraineurs may also complain of palinopsia (see later discussion), the persistence of visual images. However, palinopsia is more characteristically a symptom of parietooccipital lobe damage. Fig. 12.5 illustrates one patient’s depiction of her visual illusion associated with migraine.

Illustration by a 42-year-old female graphic artist with migraine depicting her own visual aura. She described central vision loss in the left eye with breaking up of vision with skewed diagonal lines “like a prism.” It was accompanied by a headache, which was fairly severe, but by the next day, the vision had improved.

Persistent Positive Visual Phenomena and Migraine Aura Status

In persistent positive visual phenomena and migraine aura status, uncommon prolonged migraine conditions, the visual phenomena is either (1) continuous, full-field, unaccompanied by visual loss, and not visually disabling (persistent positive visual phenomena) or (2) similar to a more classic visual aura but continuous or recurrent (migraine aura status). The visual phenomena in each type are temporally unrelated to headaches, and standard neuroimaging is negative without cerebral infarction.

Persistent positive visual phenomena . Ten patients with migraine who developed persistent positive visual phenomena without visual loss lasting months to years were the subject of the original report. None had major psychiatric disease. The visual complaints were similar in their simplicity and involvement of the entire visual field and usually consisted of diffuse small particles such as TV static, snow, lines of ants, dots, and rain ( Fig. 12.6 ). Some patients reported greater awareness of the visual phenomena when looking at the sky or at a light-colored wall. Complex phenomena such as palinopsia, micropsia, and formed hallucinations were experienced but were exceptional. Some characterized these unformed visual hallucinations as bothersome, uncomfortable, or emotionally disabling but not interfering with visual function. Other patients were unconcerned by them. Neurologic and ophthalmologic examinations were normal in all patients, and electroencephalograms were normal in eight of eight patients tested. MRI was normal without evidence of infarction in all patients except one who had nonspecific biparietal white matter lesions and another with a small venous angioma. In this series, medications such as tricyclic agents, calcium channel and beta blockers, and analgesics were unhelpful.

Persistent positive visual phenomena associated with migraine. A . A young girl’s depiction of colored constant and full-field objects she perceived. This patient is one in the series by Liu et al. B . An adult patient prepared this illustration which depicts her persistent positive visual phenomena. She described “flashes and blotches of light that had many different colors and “noise” in them, almost like TV static. These lights would come from the left and go to the right; there were always several in my field of vision at any given time.”

More recent authors have proposed a “visual snow” syndrome consisting of visual snow (i.e., TV static or TV snow) with at least two of four of the following: palinopsia, enhanced entoptic phenomena, photophobia, and nyctalopia. The “visual snow” syndrome can occur in both migraine patients as well as nonmigraineurs, and generally treatment is ineffective. One might consider visual snow to be an umbrella term, and persistent positive visual phenomena in migraineurs to be a subset of visual snow.

Persistent positive visual phenomena may result from spontaneous cortical discharges. Alternatively, selective dysfunction of inhibitory and modulating neurons in extrastriate areas, as evidenced by occipital hypoperfusion demonstrated by SPECT imaging, may have allowed spontaneous discharges from the lateral geniculate or visual cortex. This could result in release visual hallucinations (see below), as suggested by West and Cogan. Normal diffusion- and perfusion-weighted MRI suggests ischemia does not play a role.

Migraine aura status . In this condition, a more classic aura persists, typically in just one part of the visual field, and sometimes with a combination of positive and negative visual phenomena. Haas reported two individuals with “prolonged migraine aura status”; one was a 70-year-old man with a long-standing history of migraine headaches who developed a constant “pinwheel of bright whirling color, mainly yellow and red” in the left homonymous hemifield accompanied by left hand paresthesias and clumsiness. The episode lasted 5 weeks and resolved with aspirin and cyproheptadine. Examination, brain computed tomography (CT), and EEG were normal. Luda et al. reported a 65-year-old woman with “sustained visual aura” who had a 50-year history of migraine with aura who then developed 12 months of “scintillating geometric figures (in the shape of either rings or chains)” in the right visual hemifield. Carbamazepine, diazepam, flunarizine, nimodipine, and citicoline were unhelpful. Examination, EEG, and brain MRI were normal. Transient hypoperfusion documented with perfusion MRI without permanent tissue injury in a similar case has been documented.

In our experience treatment of patients with either persistent positive visual phenomena of migraine or migraine aura status is usually ineffective with most migraine medications, anticonvulsants, and antidepressants. However, Rothrock and Chen et al. reported the successful management of patients with each type with divalproex sodium and lamotrigine, respectively. In addition, acetazolamide reportedly effectively treated three patients with migraine aura status, while others were treated successfully with intravenous furosemide, nimodipine, and ketamine.

Acephalgic Migraine

In patients with acephalgic migraine, the aura is unaccompanied by headache. The diagnosis of acephalgic migraine is suggested by a previous history of migraine, the occurrence of a positive or negative visual phenomenon typical of migraine, and the absence of cerebrovascular causes for the event. Both visual hallucinations and illusions as well as transient monocular and binocular visual loss can occur. We have observed a common pattern in lifelong migraineurs of typical headaches without aura in adolescence and early adulthood then predominantly acephalgic migraines in middle age and afterward. Fisher detailed such a change in his own migraines.

When acephalgic migraine is experienced by older adults, distinguishing the event from a transient ischemic attack may be very difficult. Fisher described a group of patients older than 40 years who experienced visual symptoms initially thought to be transient ischemic attacks. However, 50% had headache, the visual symptoms were more consistent with migraine, and angiography was unrevealing. He emphasized that in adults with positive and negative visual phenomena seemingly consistent with a vascular event, migraine can be considered but must be a diagnosis of exclusion. The gradual buildup of the visual disturbance typically favors the diagnosis of migraine. Acephalgic migraine in children is very unusual, occurring in only 31 of 1106 (3%) pediatric migraineurs in one series.

The workup and treatment of acephalgic migraine are discussed in Chapter 19 .

Visual Loss (Release Hallucinations and the Charles Bonnet Syndrome)

Cogan reemphasized the notion that visual hallucinations may be associated with loss of vision. In his report entitled “Visual Hallucinations as Release Phenomena,” he presented patients with blindness of varying degree and cause, including monocular blindness due to optic neuropathy, chiasmal visual loss affecting both eyes, and homonymous hemianopia due to retrochiasmal lesions. Each had formed or unformed visual hallucinations, typically within the defective area of vision. For instance, one woman with a right homonymous hemianopia complained of “zig-zag lines, colored triangles, and formed images suggesting that people and traffic were moving in on her from the right side.” In general, the complexity of the hallucinations had no localizing value. When present, the hallucinations in his patients were usually continuous, variable, and more intense when the eyelids were closed ( Box 12.2 ). He contrasted these from the episodic stereotyped visual hallucinations associated with seizure activity. Cogan suggested that interference of the normal visual input, from any lesion in the afferent visual pathway, might allow a “release of brain activity.”

Lepore studied 104 patients with retinal or neural afferent pathway disease and found 57% reported spontaneous visual phenomena. Elementary disturbances such as photopsias and geometric forms, as well as complex ones such as people, animals, or vehicles, were described. Like Cogan, Lepore found their complexity did not correlate with lesion site. Furthermore, hallucinations occurred even in individuals with only minor amounts of visual loss. For example, spontaneous visual phenomena were described by three of Lepore’s patients with pseudotumor cerebri, 20/20 vision, and only minimal enlargement of the physiologic blind spot. Many patients in his series were relieved when informed that the visual phenomena were common sequelae of visual loss and not reflective of any psychiatric disturbance.

The suggestion that vision loss of any degree due to lesions anywhere along the visual axis can lead to release hallucinations has been confirmed by several others. For instance, detailed descriptions of simple and complex visual hallucinations within homonymous hemianopias due to cerebral lesions have been reported. Patients with complex visual hallucinations and illusions associated with visual loss due to ocular diseases were described in another study. Normal visual acuity but glaucomatous visual field loss may cause hallucinations. Visual hallucinations of all types were found in 15% of patients seen in a retina clinic and have been described in association with retinal vascular occlusions, macular photocoagulation, and macular translocation surgery. Visual hallucinations can also occur after enucleation. Release visual hallucinations usually occur within the blind scotoma but occasionally can be full field ( Fig. 12.7 ).

A,B . An 81-year-old woman’s rendering of her release visual hallucinations associated with macular degeneration and central visual field deficits. A . “The hallucinations are similar in color and content: green background lined or gridded in black with a central figure.” As one example, she saw “yellow figures in the center spinning very fast.” B . Sometimes the hallucinations were full field, as in this “vision” with “cartoon horses.” C . Another elderly woman with macular degeneration and cataracts painted and described one of her release hallucinations as green colors moving in and overtaking the blue centrally. Then the blue on the outside moves in to overtake the green centrally, and the process repeats itself.

The concept that spontaneous visual phenomena may be released by a lack of inhibitory input may also explain visual hallucinations associated with severe sensory deprivation in prisoners of war or in normal volunteers blindfolded for extended periods of time, for instance. In addition, patients with dense, bilateral cataracts, despite being alert and lucid, may experience vivid, pleasurable visual hallucinations. Many of the cataract-associated hallucinations seem to occur when the patient is not receiving external stimuli, such as in a quiet room or just before the patient goes to sleep. In further support of the sensory deprivation concept, the hallucinations often resolve following cataract extraction.

Release visual hallucinations rarely can occur in children as well. A 3.5-year-old boy with an optic pathway glioma became completely blind following tumor debulking surgery, and 1 week later reported he saw his brother, Santa Claus, and animals for 3 days.

In some cases the release hallucinations are the presenting symptom of new visual loss. We examined a 51-year-old woman who complained of seeing “a picture within a picture—like the new kind of television sets” in her lower left visual field as a presentation of a new incomplete left inferior quadrantanopia due to a right parietooccipital infarction. She described a rectangular scene with a red background filled with several people milling about, and it differed completely from what she saw in her larger intact field. Multiple broad horizontal lines swept upward over the scene, and the patient said this effect mimicked a television set with malfunctioning “vertical hold.”

The eponym Charles Bonnet syndrome has been applied to some patients with visual hallucinations associated with visual loss. However the use of the term is hampered by varying definitions. Charles Bonnet was a Swiss naturalist and philosopher who, in 1769, described his 89-year-old grandfather’s symptom complex of cataracts; blindness; and visions of men, women, birds, and buildings. Initially used to designate elderly patients with eye-related visual loss and hallucinations, the label Charles Bonnet syndrome has been used as a “wastebasket” term to describe patients with visual hallucinations without psychiatric disease or drug use (so-called isolated visual hallucinations) but with insight into the artificial nature of their visions. Most patients with Charles Bonnet syndrome are elderly and have visual deficits of varying degree due to age-related macular degeneration, diabetic retinopathy, glaucoma, cataracts, and corneal disease. However, visual loss has not been a consistent criterion for the diagnosis, and patients with homonymous hemianopias and children have also been labeled with the name. Therefore, to describe visual hallucinations due to visual loss of any cause, we favor the use of the term release visual hallucinations rather than Charles Bonnet syndrome.

The exact pathophysiology of release visual hallucinations is unclear, but one functional MRI study of affected patients demonstrated cortical activity in ventral extrastriate areas. In addition, the hallucinations corresponded with activity in the region’s functional specialization; for example, visions of faces were associated with activity in the fusiform face area.

Evaluation

In a patient with visual hallucinations with known visual loss, release phenomena should be suspected but is a diagnosis of exclusion. Stereotyped images and accompanying motor activity or autonomic symptoms suggest seizures. Any history of psychiatric disease or drug use should be excluded. The patient’s mentation should be normal, and ideally he or she should have complete insight into the unreal nature of the hallucinations.

There should be a low threshold for an EEG to rule out seizure activity. Neuroimaging is unnecessary if the cause of visual loss is ocular. However, if the cause of the visual loss is not ocular in origin, we would recommend neuroimaging to ensure there was no change in the original lesion, such as a hemorrhage, new stroke, or tumor growth. Neuroimaging would also be indicated if the EEG were abnormal. Finally, because release hallucinations can be the presenting symptoms of new visual loss, careful assessment of afferent visual function, such as acuity, color vision, and visual fields, should be performed, and the appropriate workup should be undertaken if a new visual deficit is detected.

Treatment

Many affected patients, particularly if they are elderly, find the hallucinations frightening or embarrassing, and are concerned about a diagnosis of insanity or dementia. Therefore, the best treatment of release visual hallucinations is physician recognition, patient education, and reassurance, which most patients find extremely comforting. Vision loss should be corrected, if possible. Patients with depressive symptoms may benefit from appropriate pharmacologic therapy. Psychotherapy and medications in general are unhelpful in this disorder, but antipsychotic medications in some instances may diminish the hallucinations.

Ironically, in some patients with hallucinations associated with progressive visual loss, the hallucinations resolve as their vision worsens. Some patients experience reduction of symptoms with increased lighting, which perhaps increases visual stimuli. Similarly, rapid eye movements, which may help release hallucinations by filling in scotomas in visual scenes, can be helpful.