You Are Dr. House

A physician’s assistant from the orthopedic clinic, a talkative, blonde, fifty-something woman, dropped by to ask me to see a patient because of her abnormal gait. I was newly retired from the Army, now working as a civilian contractor at a small Army hospital outside of DC. 

“I saw this patient because of her right foot,” she said. “It was run over by a car because she couldn’t get out of the way. Some kids horsing around. I think she was thirteen. Anyhow, the car started rolling and all the others got out of the way. But not her. Clumsy, I guess. Her foot was crushed pretty badly and she’s had problems with it ever since. She’s thirty-four now.”

“You want me to see her because of her foot?” I said.

“Oh, no, no,” she said. “I was seeing her because of her foot and as she was leaving, I noticed her walking looked pretty abnormal. More than I could explain just because of the foot. No, I think something is wrong with her gait that might be neurologic. Could you take a look at her?”

Tiana came in with her husband a few weeks later. She told me the story about her foot. Then I asked about her walking. 

“What about my walking?” she said.

“They asked me to see you because of the way you walk. Are you having problems walking?”

“Well, yes, but it’s nothing new. I’ve always walked this way. Nothing has changed. My legs are just stiff.”

Tiana’s husband had known her for six years and said her gait had been abnormal for all that time, maybe growing a little worse. She related having pain at times in the thighs and calves, worse with walking, and that her legs often felt weak. She sometimes felt pins and needles in both feet. She denied any problems with her arms or hands. 

I asked if she had ever seen a doctor about her problems walking. She said her parents had taken her to pediatricians when she was small because of her abnormal gait.

“Do you know what they said was wrong?”

“They said I had cerebral palsy.”

I asked about her family history. She told me her father used to drag his feet and walked with a cane. Her mother wound up in a wheelchair, but because of spine surgery. And then she mentioned her older brother. At age 40, her brother was on disability, dragged his feet when he walked, much like Tiana, and sometimes used a wheelchair.

“Do you know what’s wrong with your brother?” I asked.

“They say he has cerebral palsy, too.” she said.

Tiana’s neurologic examination showed she had mild weakness in both legs and marked spasticity in all four extremities. Spasticity refers to an increase in muscle tone with specific characteristics that distinguish it from other conditions causing increased muscle tone. It affects certain muscle groups more than other muscle groups. Spasticity is also velocity dependent, becoming much more pronounced with rapid movements than with slow movements. 

Spasticity occurs with pathology that affects the corticospinal tract, the large white matter tract that originates in the cerebral cortex and conveys signals to motor neurons throughout the entire length of the spinal cord. The corticospinal tract is one of the largest and most important pathways in the entire central nervous system. 

Tiana had abnormally brisk reflexes in both her arms and legs. When I tapped her knees with my reflex hammer, her feet shot out too far and too fast. When I scratched the soles of her feet, her big toes went up, an abnormal finding known as a Babinski sign. 

Brisk reflexes and Babinski signs both indicate corticospinal tract pathology. Her gait showed severe spasticity with “scissoring”—the knees held tightly together, feet on tiptoe and wider apart than knees, the advancing knee sweeping around and in front of the stationary knee with each step, with the trunk swaying side to side to maintain balance.

I explained to Tiana we would do some blood tests and MRIs to look into her problem further. But I already had a pretty good idea, and one thing seemed clear—this was certainly not cerebral palsy. 

The term cerebral palsy originated to refer to children who have neurologic deficits from birth or very early in life. Causes include prematurity, intrauterine infection, congenital brain malformations and perinatal stroke or intracranial hemorrhage. Another cause, less common than once thought, is fetal oxygen deprivation during birth due to such things as maternal hemorrhage, prolonged and difficult delivery, malpresentation and umbilical cord strangulation. 

But physicians often apply the appellation cerebral palsy to any child who fails to achieve normal motor and intellectual milestones for any reason, frequently without much in the way of investigation.

Cerebral palsy has several forms. It frequently, but not always, devastates the intellect. Nowhere is the sparing of the intellect that can occur more dramatically demonstrated than in the TED talk I Got 99 Problems … Palsy Is Just One by a victim of the choreoathetotic form of cerebral palsy, the comedian Maysoon Zayid. 

A third-year medical student with a form of cerebral palsy that often spares the intellect once rotated on my service. She was brilliant. The team always took the elevator as our only concession to her disability. She became a pediatric neurologist and went on to direct the cerebral palsy clinic at a major university medical center. 

One of the most common forms of cerebral palsy causes spastic weakness of both legs, referred to as spastic diplegia. Despite the leg weakness affected patients can walk but have the typical spastic gait with scissoring. The most common cause of this striking gait disturbance is the spastic diplegia form of cerebral palsy. 

But cerebral palsy is not the only cause.

I told Tiana to bring her brother along when she returned for her test results, unofficially, just as a companion. Tiana, a military dependent wife, was eligible for care. Her brother, a civilian, was not. But I could do a quick neurologic exam, off the record, office door closed, and see how whatever he had compared to whatever his sister had.

In terms of neurologic examination, her brother was essentially her twin. Same leg weakness, same spasticity, same brisk reflexes, same gait. Whatever she had, he had.

The MRIs of Tiana’s brain and entire spine showed no abnormality. All the blood tests were normal, including the vitamin B12 and copper levels, critically important in this situation.

After we discussed all the test results, the time came to let them know what I thought. I sat behind my seen-better-days government desk. Tiana and her brother sat side by side across from me, wearing expectant expressions. 

“I’m not sure how to tell you this,” I said, “but neither of you have cerebral palsy.”

Their eyes widened in surprise at this unexpected news, being told a diagnosis they had carried since childhood was wrong.

“What do you think it is then?” asked Tiana’s brother.

“Let me explain. You both know you have spasticity in your legs, right?”

They both nodded.

“When a person has weakness in both legs, as both of you do, we refer to that as paraparesis or paraplegia. When a person has spasticity and paraplegia, we call that spastic paraplegia. Sometimes spastic paraplegia can run in families. You both have it. You both have exactly the same thing. Your neurologic examinations are identical. Your gaits are identical. You have the same condition. You know this is true, right?”

Again, they nodded. Tiana said, “We’ve always known we had the same thing, we just thought we both had cerebral palsy.”

“The problem with that,” I said, “is that cerebral palsy is not hereditary. It does not run in families. The odds of a brother and a sister both having cerebral palsy are remote. Unheard of. No, what you have is hereditary. And your father probably had it too. You told me he dragged his feet and used a cane, right?”

“Yes, he did,” Tiana said. “He died when we were small so I can’t remember much else.”

“Well, from that description and having examined both of you, it’s likely your father had the same thing. There is a condition that runs in families, that is hereditary, and causes spastic paraplegia. It’s called hereditary spastic paraplegia. That is what I think you have. We can do some genetic testing and try to find out for sure.”

Tiana smiled, looked at me and said, “You are Dr. House.”

Hugh Laurie played Dr. Gregory House, the lead character of House, M.D., an American TV show that ran from 2004 to 2012. Dr. House, an irascible, misanthropic, Vicodin-addicted medical wizard and master diagnostician, achieved fame as a precocious and clinically astute medical detective who could figure out difficult cases and ferret out the diagnosis that had eluded other physicians. House had a bad leg and used a cane. I hoped Tiana was comparing me to Dr. House because of his legendary diagnostic skills and not because of his prickly personality.

Hereditary spastic paraplegia (HSP) causes progressive degeneration of the corticospinal tracts that leads to lower extremity weakness and spasticity. Investigators have shown that HSP is not one disease, but a group of familial diseases with similar features. Geneticists have found autosomal dominant, autosomal recessive and X-linked forms. As of now, over one hundred known genetic mutations at different loci on various chromosomes can cause the disease.

Tiana’s genetic testing uncovered no abnormality, but the available testing could only screen for a limited number of the many known causative mutations. The negative genetic testing did not rule out the diagnosis. Her workup had shown no evidence of any other disease process and the family history and her brother’s examination made any other diagnosis unlikely. 

A common misdiagnosis in patients with hereditary spastic paraplegia is the spastic diplegia form of cerebral palsy. 

Tiana worked as a CNA, a Certified Nursing Assistant, a job that involves a lot of walking and physical labor. With her brother already on disability, I thought she could qualify if she wished to apply and was willing to help. I found merely watching her walk painful. Imagining her walking up and down the halls of a hospital all day made my joints hurt. 

Tiana had no interest in applying for disability. She made only one request. She wanted me to write her a prescription for a walking cane. She might get around a little better if she walked with a cane—like Dr. House.