When Stroke Affects the Frontal Lobe
Of the four lobes that make up the cerebral cortex, the frontal lobe is the largest. It plays a huge role in many of the functions that make us human — memory, language, movement, judgment, abstract thinking.
Right Up Front
As its name implies, the frontal lobe (FL) occupies the front area within our skull. It stretches from the forehead to a little more than halfway across the skull. The FL comprises a number of folds or ridges, called gyri, plural of gyrus, that give the cerebral cortex its distinctive wrinkled surface. Right above the eyes is the prefrontal cortex. The FL has left and right segments.
“The frontal lobes take up between a third to a half of the cerebral cortex,” said neurologist Stephen Nelson, associate professor of pediatrics, neurology, neurosurgery, and psychiatry at Tulane University School of Medicine in New Orleans. “Within the frontal lobe, there are sub-regions that have important functions, but these separate functional areas don’t have discrete folds to separate them.” Those functional areas have been mapped over time by observing and matching deficits with the location of the injuries.
Its many functions
Dr. Stephen Nelson
“The frontal lobe is full of dopamine-sensitive neurons, and they’re involved in many tasks like reward, attention, short-term memory, planning and motivation,” Nelson said.
The neurotransmitter dopamine is a chemical released by nerve cells to send signals to other nerve cells. “The frontal lobed interacts with a number of other parts of the brain like the thalamus and deeper structures to help modify behavior. The frontal lobe drives a lot of motivation and positive-negative reinforcement. When you’re trying to modify people’s behavior, that’s down to the frontal lobe.” The brain includes several distinct dopamine pathways, one of which plays a major role in reward-motivated behavior. Loss of these pathways is one of the reasons that patients can become amotivated.
The FL contains Broca’s area, which is a cluster of neurons in the dominant hemisphere (left hemisphere if you’re right handed). “Damage to Broca’s area can produce Broca’s aphasia, which is a non-fluent aphasia,” Nelson said. Survivors with this condition have difficulty with word production. Their comprehension is relatively normal, but they have a hard time coming up with grammatically correct sentences and their speech is typically limited to short phrases and incomplete sentences. They have trouble getting their words out.
“Broca’s area, which is for generating speech, connects through a curved bundle of nerve cells to Wernicke’s area, located in the temporal lobe,” Nelson said. “Basically, Broca’s area starts you being able to generate speech and then Wernicke’s area helps you produce the correct words. People with Wernicke’s aphasia, speak fluently but say garbage; they don’t use the correct words. Nor do they understand what is being said to them, whereas survivors with Broca’s aphasia have normal comprehension.”
The motor cortex is situated at the back of the FL. “The motor cortex controls movement, so any damage to it will result in weakness,” Nelson said.
However, the motor cortex gets blood from both middle cerebral and anterior cerebral arteries (MCA and ACA), and a clot in either produces different deficits. “If you get an ACA stroke, you’re going to get paralysis or weakness in the leg on the opposite side,” he said. “An MCA stroke is going to produce weakness in the face and arm on the opposite side.”
An injury to the motor cortex can produce other deficits. “For example, you can get the compulsive mimicking of other people’s facial expressions,” he said. “If you make faces at them, they compulsively make faces back.” Another possible deficit is called ‘motor perseveration,’ meaning that the survivor compulsively repeats movements when the situation requires it to change, e.g., you ask someone to tap their finger and they continue to do that, even after you ask them to do something else.
Another possible deficit is a lack of motivation (known as abulia). “Abulia falls in the middle of the spectrum of diminished motivation, with apathy being less extreme and akinetic mutism — not talking or moving — being more extreme,” Nelson said. “Abulia is a syndrome characterized by apathy and a lack of motivated behavior.”
An example of this was portrayed in the movie “One Flew Over the Cuckoo’s Nest” when they performed frontal lobotomies on criminals. “If you scramble their frontal lobe, criminals are not motivated to be criminals, but they’re not motivated to do anything else either, so they just sit,” Nelson said.
Gait apraxia is another deficit related to the frontal lobe. “Apraxia occurs when a person has all the strength and coordination to do something but can’t do it,” he said. Apraxia can result from injuries to other areas of the brain, but gait apraxia is specific to an injury to frontal lobe tracts that project to the cerebellum. “Survivors have all the normal coordination and strength, but they can’t properly coordinate the posture and movements of the legs and swing of the arms and everything else necessary to walk.”
The FL plays a significant role in emotion. A stroke, or injury of the FL due to vascular dementia, can result in significant behavior changes.
“Specifically, survivors can get things like excessive emotional responses, jealousy, loss of sense of humor, lack of empathy, or they can become apathetic,” Nelson said. “They may have inappropriate or random responses to stimuli or random and repetitive behaviors. They might laugh or cry inappropriately, or they might have no emotional response.”
Unlike the motor cortex, which is a discrete region of the FL, there is no ‘emotional cortex.’ It appears that injury to any part of the cortex can have at least some emotional component. “Anybody who has any kind of damage to the frontal lobe can have challenges controlling emotions or experience emotional changes,” Nelson said.
“I think it’s, by far, the stroke area where people have the most emotional issues. Sometimes, that’s mistaken for depression. But the good news is that the apathy and other emotional issues may actually get better with time just like the physical weakness can get better.”
Executive Function & Response Inhibition
Executive function involves the ability to think abstractly, see consequences and make decisions based on that analysis rather than in response to emotion. Survivors with FL injury may interpret figurative ideas in a literal fashion, e.g., people who live in glass houses shouldn’t throw stones because broken glass can cut you.
“Patients may have difficulty with logical thinking, abstract thought or even math,” Nelson said. It would be difficult for them to work out a math/logic puzzle.
“Partly we know that the frontal lobe is important for this kind of thinking by observing children and adolescents,” he said. “Our frontal lobes aren’t fully developed until our 20s, which is why you can’t talk to young children like they are adults, or why teenagers often engage in risky behaviors like driving too fast or drinking and driving. Their frontal lobes are not developed yet, and they don’t understand the concept of, ‘No, I’m not invincible, I’m not going to live forever,’ they don’t make that leap. They just think about what’s fun right now.”
Response inhibition goes along with executive function. Understanding future consequences is connected to the capacity to think abstractedly. Nelson uses an example: “If your wife says, ‘Does this dress make me look fat?’ the brain of a husband whose frontal lobe is intact goes, ‘Dingding- ding — no, you have to answer that no.’ But without input from the frontal lobe to inhibit the wrong response, he says, ‘Yup, it does.’”
Disinhibition is the inability to stop inappropriate behavior. In addition to affecting conversation, as above, other examples of socially inappropriate behaviors that can happen include telling very personal information to strangers or doing things that would typically be done in private in public.
“We see these behaviors in people who either have a big stroke or they have vascular dementia because of multiple small infarcts,” Nelson said. “Many of these issues are probably not due to a single injury to a single area but injury to multiple areas that interact. It’s a lot more complicated than say Broca’s area that’s for speech generation. It likely has to do with a network of neurons that are interacting.”
The frontal lobes help drive eye movements. “Though our eyes are primarily controlled by cranial nerves that come off the brainstem, it turns out there are eye fields in the frontal lobe,” Nelson said. “So, if the right frontal lobe and motor cortex are injured by a stroke in the middle cerebral artery, you get weakness on the left, and your eyes actually drift to the right and you don’t look to the left as well. Additionally, the frontal eye field is important for visual attention and moving the eyes to focus on new targets in the survivor’s visual field.”
Recovery & therapy
“I think that in general, all stroke patients can get recovery, but there are three things that drive that: the age of the patient, their health before the stroke, and the severity of the stroke,” Nelson said. “A patient’s other medical issues at the time of the stroke impact how well they can recover. The older you are, the more difficult it is to recover. If you’re already neurologically impaired prior to the stroke, then the chance of recovery is going to be a lot less than if you were neurologically normal beforehand. And of course, a small stroke is much easier to recover from because there is much more healthy brain left to compensate for the damaged part of the brain. A large injury can be very difficult because you lose so much pliable brain.”
Of course, therapy helps. Nelson points to four major components of therapy.
“Anyone experiencing weakness, should have physical therapy. Of course, speech therapy if there are speech problems. And third, you want to treat any psychiatric or behavioral issues that may also be occurring, like depression. Fourth, you need to treat any medical issues like diabetes, atrial fibrillation or high blood pressure to make sure that the patient doesn’t have a recurrent stroke.”
I have finally accepted the new me.
Julie Thomas of Staunton, Virginia, had a left frontal lobe stroke while still in the hospital after a heart catheterization in 2006, when she was 48 years old. “The damage was about the size of a pea,” she said. The consequences were much bigger.
Her short-term deficits were problems with speech and cognition: “I couldn’t process abstract ideas or focus and organize my thoughts,” she said. Her short-term memory, balance and ability to read were also affected. Speech therapy helped as did water aerobics, which she attended three times a week.
“At first, I was terrified of waking up and not recognizing my family,” she said. “I didn’t want to sleep in case things got worse while I slept. I also slept with a light on and cried a lot.” A workaholic, she hated being home all the time. “I think the most notable emotion I experienced was anger: I was angry at the clot that had broken loose and traveled to my brain; I was angry at myself because I was not as capable as I once was. After the anger came the realization that I was blessed, and I was thankful to have my family, thankful to be able to work again part time, thankful to drive again. However, I went back and forth between those two emotions.”
A career Air Force couple, Julie and Wayne had moved to Staunton with their three children when Wayne retired from active service. He took a job on the night shift at a Hershey Chocolate factory. Julie went to work as a bank teller while their kids finished school and returned to that job part time four months after her stroke. “I was fine until we changed computer systems,” she said. “Even though I trained on the new system, I had trouble retaining and organizing that information. I worked too slowly and was overwhelmed easily.”
Pre-stroke anxiety became post-stroke panic attacks, and the medications to control them put her on an emotional roller coaster for a long time. Five years after her stroke, her branch got a new manager. “He was the type that managed by intimidation,” she said. “He was always pulling someone into his office and closing the door; only to have them leave in tears a short time later.” That job was no longer a good fit for her, and she left the bank for the less stressful work of directing the church choir and teaching water aerobics — endeavors she is still engaged in. “It’s the perfect position for me since I was a music major in college,” she said. “I sing, play classical guitar, a little piano, some violin and basic percussions. And I have always been a ham, which makes me perfect for my second part-time job as an aqua aerobics instructor at the Staunton/ Augusta YMCA. I love the water and swimming.”
She still contends with the long-term deficits — trouble with organization, depression and anxiety and “saying inappropriate things,” she said. “I have a tendency to say what is on my mind. That doesn’t always go over too well.”
In addition, her balance is compromised. Before her stroke she had achieved a Bo-dan belt (right below black belt) in tae kwan do, but she no longer has the balance — “or the knees” — to do it.
She also has a form of retrograde amnesia, where she forgets things for a few weeks and later remembers them in detail. “At first, I thought it would go away, but it hasn’t,” she said. “This really gave me problems at the bank. I wrote everything down, extensive notes, but it didn’t always help. I finally had a lapse in memory that hurt a client’s confidentiality, and I decided then and there to retire. I felt like a hindrance to the company. I felt like I was drowning and wondered why I had put five years of my life into trying to prove that I could still do my pre-stroke job. I guess my ego got in the way.”
Julie and Wayne’s youngest child, Elizabeth, has developmental disabilities and cannot live alone. Although age 30, she has the maturity of a 14-year-old. “Her depression and anxiety are severe, and she has anxiety attacks where she screams, pulls her hair, hits herself,” Julie said. “I’m the only one who can calm her. I have to put my arms around her to keep her from hurting herself and speak softly to her until it passes. She is afraid of people hurting her and won’t go out alone. She constantly talks about wanting to die. I have to be on my toes and pay attention. Even if I am exhausted or frustrated I have to be even-tempered and gentle when dealing with her.”
Today, Julie is at peace with her life. “I have finally accepted the new me. I know what my limitations are and try not to exceed them,” she said. “I still feel blessed. My faith never did falter. It got me through.
“The hardest was being patient with myself. I had always been perfectionist and I can’t do that anymore. I’m more willing to take life one step at a time. Everybody tells me that I’m much nicer than I used to be. Our family, while always close, is even closer now. Wayne, Elizabeth and I call ourselves ‘The Three Musketeers.’”