Motion blindness, also called akinetopsia, is an extremely rare condition with only a few documented cases.1,3 People with this condition cannot perceive visual motion despite being able to see stationary objects without a problem.
Moving objects appear as stop-motion frames in a movie reel or disappear entirely. An inability to detect motion causes difficulty with many daily tasks, such as driving, cooking, and watching television.
Akinetopsia has no known cure or effective treatment. This article explores what the scientific community knows about akinetopsia, including its causes, symptoms, and management.
What is Akinetopsia?
Akinetopsia, or motion blindness, is a rare visual perception disorder. It’s due to a problem with the brain rather than the eyes, which is why it’s sometimes called cerebral akinetopsia.
There are two categories of cerebral akinetopsia:
Inconspicuous Akinetopsia
This is the most common type of akinetopsia, though it’s still rare. People with inconspicuous akinetopsia perceive motion as a series of still images or a movie reel.
For example, pretend you tossed a ball in the air. A person with normal vision would see the ball move in a continuous arc. Someone with inconspicuous akinetopsia would see the ball jump from frame to frame. To them, the ball may look like it’s moving in slow motion. This is called stroboscopic vision.
People with this type of akinetopsia may also experience visual trailing. It means moving objects leave a trail of afterimages.
Gross Akinetopsia
This is the most rare and severe type of visual motion blindness. Unlike the inconspicuous type, people with gross akinetopsia don’t see moving objects as a movie reel. They have no visual motion perception at all.
This type of akinetopsia might cause scenery to become invisible while looking out the window in a moving vehicle. When pouring tea, the liquid may appear frozen instead of fluid.3
Symptoms of Akinetopsia
Symptoms of cerebral akinetopsia may vary depending on the type and severity of the condition. They include:
- Inability to perceive motion. Stationary objects are visible but not moving objects.
- Stroboscopic vision. Objects jump from frame to frame, like on an old movie reel. It can also look like the object is moving through a room with strobe lights.
- Visual trailing (palinopsia). Copies of an image remain in the visual field after the moving stimuli cease.
- No movement vision. Moving objects seem to disappear or become frozen.
Causes of Akinetopsia
Very little is known about the exact causes of akinetopsia because so few cases have been reported. Studies indicate that akinetopsia is related to impairment in the part of the brain responsible for visual motion processing.1-3,5
Possible causes of damage to this part of the brain include:
- Stroke
- Brain lesions (cortical lesions)
- Side effects of medications
- Traumatic brain injury
- Neurodegenerative conditions such as Alzheimer’s disease
Who is at Risk of Akinetopsia?
Akinetopsia can affect people of any age, gender, race, and ethnicity. Some conditions may increase your risk for akinetopsia.
These conditions include:2,4
- Brain tumors
- Alzheimer’s disease
- Traumatic brain injury
- Post-concussive syndrome
- Receiving transcranial magnetic stimulation
- Use of certain antidepressants in high doses, such as nefazodone
These risk factors don’t ensure you’ll get akinetopsia. It’s an extremely rare condition. Talk to your doctor if you’re concerned that a particular treatment may increase your risk for akinetopsia.
What Part of the Brain Is Affected by Akinetopsia?
The specific region of the brain involved in akinetopsia is known as the visual area V5/middle temporal cortex (V5/MT).1-3,5 V5/MT is part of the brain’s visual cortex, located at the back (posterior) side of the brain in the outer layer (cerebral cortex).
The visual cortex is on both sides of the brain. Most cases of akinetopsia involve damage on both sides (bilateral lesions).2 However, some cases have damage on one side (unilateral lesions).3
Different areas of the visual cortex are responsible for processing specific visual information. Area V5/MT plays a major role in visual motion perception and integration. It also helps guide some eye movements.
Transcranial magnetic stimulation (TMS) is a procedure that mimics the effects of temporary brain lesions. TMS studies show that akinetopsia can be selectively and temporarily induced by stimulating the V5/MT region in healthy subjects.2
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Akinetopsia Diagnosis
To diagnose akinetopsia, your doctor will perform a thorough physical exam and review your medical history. They will ask about head injuries, medication use, and other health conditions.
They may order neuroimaging studies, such as a cranial computed tomography (CT) or magnetic resonance imaging (MRI) scan. These can help rule out other conditions.
Additional testing may be required to determine the underlying condition causing akinetopsia.
Possible Complications of Akinetopsia
Akinetopsia can cause severe emotional distress that decreases a patient’s quality of life.
The condition affects a person’s ability to perform simple, everyday tasks like preparing food. It also keeps them from driving, crossing roads on foot, and participating in sports.
An inability to perceive motion also causes difficulty following conversations because lip movements aren’t detected.
Akinetopsia Treatment
Akinetopsia is challenging to treat because it’s rare, and much about it remains unknown. There are no medications approved to treat akinetopsia.
However, a case study of an epileptic seizure patient experiencing episodes of akinetopsia found relief from carbamazepine.2 In this case, the akinetopsia occurred as seizures, so carbamazepine may not work for others.
More often, people learn to cope with akinetopsia by managing the symptoms. Management may include:
- Vestibular and visual rehabilitation
- Learning to rely on other senses, such as hearing, to estimate distance and interact with others
Summary
Akinetopsia, or motion blindness, is a motion perception disorder. It’s extremely rare, with only a few reported cases in history.
Inconspicuous akinetopsia causes motion perception that resembles still frames on an old movie reel. Gross akinetopsia is a complete inability to detect motion.
Akinetopsia is typically caused by bilateral brain damage in the V5/MT region of the brain. This can result from a brain injury, medical conditions like stroke and Alzheimer’s disease, and taking high doses of certain antidepressants.
Call your eye doctor immediately if you experience symptoms of akinetopsia or another problem with visual perception.
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