On Monday, two more former patients of Dr. Gary Weiss filed suit against him, alleging that he negligently misdiagnosed them with multiple sclerosis and gave them unnecessary treatment for years.

The next day, the former Vail neurologist issued a blistering rebuke of the allegations, citing the difficulty of diagnosing MS and questioning the credibility of Dr. Mark Pithan, who bought Weiss’ former practice and is now suing him after initiating at least 20 overturned diagnoses. Pithan could not be reached for comment, and his attorney declined to speak to the press.

The first lawsuits against Weiss came on Aug. 19 and were filed separately by a woman from Frisco and another from Avon.

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Diagnosis debate

The dispute highlights the ambiguity of MS diagnoses and debates among neurologists nationwide regarding diagnostic procedures and the timing of treatment. Since there are no definitive tests for MS, doctors must make a clinical diagnosis, or one that weighs a full-patient profile against the presence or absence of MS indicators in physical symptoms, MRI scans and lumbar punctures. The disease, which destroys the protective sheaths of neurons, has no cure but can be controlled by powerful, disease-specific drugs.

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The patients’ lawsuits note that Weiss failed to get a lumbar puncture to confirm his diagnosis, reflecting a criticism leveled by some neurologists, like Andrew Solomon of the University of Vermont College of Medicine, that over-reliance on MRI scans leads to more MS misdiagnoses. Weiss, however, disputes that.

“Multiple sclerosis is an extremely difficult disorder to diagnose,” Weiss wrote. “Contrary to the implications in the lawsuits, a physician cannot simply examine the results of an MRI or a spinal tap and arrive at a definitive conclusion.”

In an email, he said he looks at his patient’s case in-depth and has long discussions with them before beginning treatment.

But, according to John Corboy, a neurologist at the University Colorado School of Medicine, ambiguity is not unique in medicine.

“Many diagnoses are made less directly and based on multiple factors. MS is like that, but so is diabetes,” he said. “Like every condition we diagnose, we have specific diagnostic criteria for MS.”

At least four different doctors from around the state have overturned Weiss’ original diagnoses.

Medical licenses

Weiss questioned the credibility of Pithan, who began recommending second opinions on MS diagnoses just a month after purchasing Weiss’ practice in July 2013. Pithan paid $1.344 million for the business, according to court documents, but says this value was inflated by high numbers of patients falsely diagnosed with MS.

Colorado Medical Board records show that Pithan agreed to temporarily suspend his medical license, after a May 2015 DUI led into a board inquiry as to his ability to safely practice medicine. He denies violation of the Medical Practice Act but voluntarily entered into an interim agreement to not practice while his case is open.

Weiss suggested this undermines the doctor’s credibility in the legal dispute. Pithan could not be reached for comment on that claim.

As for Weiss, he said that his own forfeiture of his Colorado medical license a year after selling his practice was unrelated to a board investigation of his MS patients. Rather, he said he was diagnosed with a medical condition preventing him from living at elevation and thus decided to settle the matter by agreeing to not practice in Colorado.

“I regret that decision today because of the appearance it caused that I might be conceding the allegations in the complaint,” he wrote.

The terms of Weiss’ settlement with the medical board don’t mention that medical condition or explicitly define why he was no longer licensed to practice medicine in the state.

Early treatment

Weiss said that in his practice he didn’t hesitate to begin treatment if he suspected MS. There is research suggesting that this early treatment may head off worse symptoms down the road. In a 2007 study, 24 percent of patients that didn’t receive immediate treatment showed signs of worsening MS versus 16 percent of patients who did.

However, some in the neurology community are concerned this leads to over-diagnosis of MS, which can mean side effects and costs of up to $100,000 per year for unnecessary treatment. In a survey of MS specialists, researchers found that more than 95 percent said they had seen at least one patient in the past year that had been diagnosed with MS but they “felt strongly” did not have the disease.

Complicating the picture further, there is a range of other explanations for MS-like symptoms, such as strokes, migraines or even high blood pressure. In a 2003 study, two-thirds of 281 patients referred for MS symptoms turned out to have different conditions.

“People will often present with an isolated attack of some kind that can look like MS,” Corboy said. “Then, there could be a weird spot on a MRI scan, but that would not necessarily indicate MS.”

Patients might thus undergo great emotional stress and expense for treatment that doesn’t fix the real cause of their symptoms — and even poses risks of its own.

In an email, Weiss wrote that only a small percentage of patients experience side effects, and that it is rare to see long-term problems. He said he would rather give treatment to some who didn’t need it in order to prevent further deterioration in those who do. In his view, he is preventing MS by implementing aggressive treatment at the first signs.

Corboy, however, took issue with that perspective: “If anybody were to say, ‘We can never make a totally firm diagnosis, so we should treat as soon as we can,’ I would say that is completely untrue.”

He noted that all MS drugs have risks, especially Tysbari, which can cause a neurological disease with a 25-percent mortality rate that leaves survivors severely disabled. According to a lawsuit filed by one of Weiss’ former patients, he treated her with this drug for nine years before she was told by Dr. Enrique Alvarez of the University of Colorado Hospital that she didn’t have MS.