It May Not Be Parkinson’s: A Look at Corticobasal Degeneration

African American man (60s) in wheelchair holding hand weights, ready for physical therapy session.

Partners in FTD Care, Winter 2021
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Corticobasal degeneration (CBD) is a rare neurodegenerative disease that results in nerve cell loss, scarring, and shrinkage of the deeper layers in the brain’s frontal and parietal lobes. (Corticobasal syndrome, meanwhile, is its most common presentation based on the pathological symptoms.) Due to their similar presentations, CBD often is initially diagnosed as Parkinson’s disease. Early CBD symptoms include rigidity, slowness of movement (bradykinesia), and involuntary muscle contractions (limb dystonia) and spasms (limb myoclonus), often occurring on only one side of the body. Understanding the disease prevalence and progression can assist healthcare workers in referring persons to appropriate services, while also aiding in research. The case of David M. illustrates the difficulty in obtaining an accurate diagnosis and the importance of assembling a team to assist in diagnosis, treatment, and emotional support.

The Case of David M.

David M. is a 52-year-old senior portfolio manager for an international banking firm. Consistently praised for his business savvy and financial intelligence, David holds a PhD and multiple master’s degrees, and has worked his way up the corporate ladder. Two years ago, while attending a work conference, he first experienced movement issues. An avid runner who was usually quick on his feet, David found himself tripping while climbing stairs, and even simply moving from room to room. At the time, he blamed his stumbling on a lack of sleep, but a few months later, he noticed additional abnormalities: His left hand started to tremble and stiffen when buttoning his shirts and tying his shoes, and he had trouble accepting change from the cashier when ordering his morning coffee.

A few months later, while camping with his brother Jacob, David found himself unable to get out of his sleeping bag in the morning. He felt as though he was stuck on the ground, unable to move his left leg or arm. After multiple attempts to stand, he called out to Jacob (who had previously noticed David moving awkwardly while hiking). Growing worried, and without a partner at home to confide in, David told his brother about the challenges he had been facing recently. Unsure how to proceed, Jacob suggested that David see his primary doctor, who may be able to provide insight.

Due to the issues in David’s extremities, his doctor suspected Parkinson’s disease and referred him to a neurologist, who had him take a balance test and a grip test, among other physical assessments. While the neurologist did not issue a formal diagnosis, he told David his symptoms fell under the umbrella of atypical Parkinsonism. He recommended the drug carbidopa-levodopa to help control his Parkinson’s symptoms.

Path to Diagnosis

David was unsatisfied with the doctor’s diagnosis, and the medication was not helping with the rigidity or tremors in his left arm and leg. His problems performing once routine tasks with his arm, which first manifested as difficulties in collecting change from cashiers, now appeared more frequently: He began to struggle with grasping and using the television remote, kitchen utensils, and doorknobs. His left leg, meanwhile, jerked uncontrollably, seemingly moving on its own; he could not fully straighten it while standing. (He would later learn that the term for this phenomenon is “alien limb.”) He also began having more trouble remembering simple math equations at work and relied increasingly on a calculator for simple addition and subtraction.

Determined to get a diagnosis that would accurately explain these progressive changes, David decided to try one more doctor—a neurologist who specializes in movement disorders. In addition to routine testing, this neurologist listened attentively as David explained his symptoms and their impact on his daily functioning. Based predominately on his symptomatology, the neurologist diagnosed David with corticobasal syndrome (CBS), a neurological condition that primarily affects movement and is associated with degeneration of the brain’s frontal and parietal lobes. Specifically, the neurologist based his diagnosis on the movement issues found in David’s left side (which is unique to CBS); his issues with gait, coordination and walking; and his inability to perform simple mathematic calculations.

CBS is a progressive condition, and the neurologist estimated that David had four to six years to live. Despite the grim prognosis, David was relieved that he finally had a name for his condition. But he decided to keep his diagnosis to himself as to not upset family, friends, or colleagues. He established routine follow-up appointments with the neurologist who had diagnosed him; of all the doctors he had seen, he felt he had been most attentive to his symptoms.

David and his neurologist started to put together a team of specialists. The doctor said that therapy would be beneficial to him throughout the disease. He recommended the use of speech therapists, to assist with cognition, speech, and swallowing; physical therapists, to work on gait and balance concerns and aid in the use of assistive devices; and occupational therapists, to help David perform activities of daily living, thus maintaining his independence.

Managing Symptoms at Work and at Home

Determined to work as long as possible, David returned to the office following his diagnosis and continued his business as usual. Meanwhile, he began going to therapy as recommended by his neurologist. As his disease progressed, performing tasks involving fine motor skills became more difficult, but occupational therapy provided creative ways to complete his daily tasks despite his growing impairments. Physical therapy helped him loosen his muscles, which had tightened painfully in recent months, and allowed for better fine and gross motor movement. Speech therapy strengthened his vocal cords and even slightly improved his swallowing.

But as the months passed, David’s job performance worsened. Colleagues increasingly questioned his work, whether in budgets or investor portfolios, and he struggled to write financial reports and file paperwork. David grew frustrated and defensive, and refused to acknowledge to himself that these errors were a result of his diagnosis.

David frequently made use of the company car to travel to off-site meetings. After several instances where he returned the car with a new set of dents and scratches, David began to be questioned by his supervisors. A coworker who often accompanied him on meetings mentioned to his bosses that David had developed a tendency to wander into the left lane while driving, and nearly collided with oncoming traffic on multiple occasions. When his supervisors confronted him, an infuriated David refused to give up the keys, and blamed the damage to the company car on other drivers and their inability to safely navigate the road.

At home, David continued having trouble with his left hand, which made cleaning nearly impossible, as he lacked the motor control and grip strength to use a broom or put away clothes or dishes. His ability to navigate stairs got worse. Still worried that news of his diagnosis would upset his family, he hired cleaning professionals to help around the house, and began sleeping on the couch to avoid going up and down the stairs, which he knew from experience could lead to falls.

At his office he used the elevator in lieu of the stairs. One day, however, a colleague he was accompanying to lunch suggested they bypass the line for the elevator and walk down the three flights to the ground floor. David did not want to raise any suspicions, so he hesitantly agreed. But about halfway down the first set of stairs, David’s left leg stopped cooperating, causing him to fall down the remainder of the stairwell. After determining that David could not get back to his feet, his colleague immediately called an ambulance, and his company’s human resources manager called Jacob, David’s emergency contact.

After the Fall

Jacob met his brother at the hospital, where David revealed his CBS diagnosis. Jacob insisted that David move in with him and his family. The brothers also agreed that it was time for David to tell his boss, who thought it best that David retire early.

Jacob was happy to support his brother; watching him struggle for so long made him feel helpless, so bringing him into his home gave him a sense of purpose. But, as Jacob would later admit to his wife, he did not know what he was getting into. David became less functional over his remaining years, losing his ability to walk without support and to move his lips and face on command, drastically decreasing his aptitude for spoken language. The two brothers, who once chatted so easily about any number of topics—sports, politics, movies—now struggled to communicate at all. Jacob began feeling less emotionally connected to his brother, which put a tremendous strain on their relationship. Attending meetings—first in person, then, as the COVID-19 pandemic took hold, virtually—of a local caregiver support group that he found through AFTD helped Jacob process his grief, as he slowly lost the brother he once knew.

Eventually, David’s swallowing issues grew more acute, and he entered hospice. Jacob vowed to provide support and education for people facing CBS and FTD, signing up to co-lead his local support group. He hopes that, by connecting with other families and persons diagnosed, he can shed light on CBS to improve diagnosis and foster a sense of hope for those navigating similar paths. David arranged to have his brain donated after his death. His autopsy confirmed that he had CBS and allowed David the opportunity to contribute to CBS research, so that others living with the disease may one day have a different experience.

Questions for discussion:

1. David is persistent in his pursuit of a clinical diagnosis that fit his symptoms. What does this tell us about atypical Parkinsonism, specifically CBS?
Like all FTD disorders, CBS is associated with degeneration of the brain’s frontal and temporal lobes. Also affected are several regions deeper in the brain that play important roles in initiating, controlling, and coordinating movement. An atypical Parkinsonian disorder, CBS is a progressive disease that presents with some of the signs and symptoms of Parkinson’s disease, but that generally does not respond well to levodopa, the most commonly prescribed Parkinson’s medication. Like classic Parkinson’s disease, atypical Parkinsonian disorders cause muscle stiffness, tremor, and problems with walking, balance and fine motor coordination. People with atypical Parkinsonism often have some degree of difficulty speaking or swallowing; drooling can be a problem. Cognitive and behavioral changes may occur at any point in the disease. Specific clinical diagnosis can be challenging for clinicians, particularly because CBS symptoms progress and change with time, and in their early stages may overlap with other movement disorders.

2. What role did physical therapy play in David’s journey with CBS?
CBS presents with multiple gait and motor function issues, such as limb rigidity, bradykinesia, postural instability, and falls. The goal of physical therapy for people with CBS is not to restore function, but to help them function within their new limitations. For David, physical therapy built strength in his muscles, allowing him to maintain his coordination for a period of time. While the literature on rehabilitation for CBS is limited, it suggests that physical therapy plays a role in managing apraxia as well as helping to maintain balance and gait.

3. Name three forms of apraxia David experienced in this case and give an example of each.
Apraxia is the inability to perform movements that typically required some practice to learn in the first place. Manual tasks or gestures become clumsy and walking can become “frozen” for several seconds at a time. The following are three forms of apraxia David experiences during his CBS journey.

  1. Limb apraxia—Inability to compel a hand, arm or leg to carry out a desired motion, although the muscle strength needed to complete the action is maintained. David frequently tripped while walking and struggled to dress himself, to use the television remote and to close his fingers around objects that were handed to him.
  2. Conceptual apraxia—People with this symptom are unable to perform tasks that involve multiple subtasks. As David’s symptoms progressed, he began to struggle with arithmetic and administrative tasks in his workplace.
  3. Facial-oral apraxia—The inability to move one’s face and lips on command. Over time, David lost his ability to swallow and speech became impaired.

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