Woman Unable to Walk or Sit Diagnosed With Rare Stiff-Person Syndrome

A 50-year-old woman in New York developed progressive leg stiffness, severe back pain, muscle spasms, fever, chills and unexplained weight loss before doctors diagnosed her with stiff-person syndrome (SPS), an extremely rare autoimmune neurological disorder.

Symptoms progressed over five years

The woman first began experiencing discomfort in her knees and back about five years before her diagnosis. Over time, her right leg became increasingly stiff, affecting her balance and causing frequent falls.

Doctors initially prescribed ibuprofen and physical therapy, but the pain and stiffness continued. She eventually developed chronic back pain, recurrent fevers and chills, and lost more than 14 kilograms without explanation.

When her symptoms worsened, she could no longer bend her legs, walk, sit or turn from side to side. She was eventually unable to get out of bed without assistance.

Doctors struggled to identify the cause

The patient first visited a hospital because of persistent back pain, knee stiffness, fever and weight loss. Blood tests showed a normal white blood cell count, providing no clear evidence of an infection.

She also did not produce antibodies typically associated with rheumatoid arthritis, HIV, Lyme disease or several autoimmune conditions that can cause pain, numbness and stiffness in the limbs.

At a later hospital visit, her arms moved normally during testing, but her legs were so stiff that doctors could not assess their full range of motion. When they tried to bend one of her knees, the quadriceps muscles at the front of her thigh contracted painfully.

Blood tests revealed stiff-person syndrome

Based on her symptoms and earlier test results, doctors suspected that she had developed stiff-person syndrome (SPS).

SPS is an autoimmune disease in which the immune system attacks healthy nerve cells involved in controlling muscle contraction. The resulting disruption can cause painful muscle spasms, stiffness, balance problems and severely restricted movement.

Further blood tests found high levels of antibodies that block glutamate decarboxylase (GAD), an enzyme involved in producing gamma-aminobutyric acid, or GABA. GABA acts as a brake on nerve-cell activity.

When GAD is disrupted, nerve cells that control movement can become excessively active. This may cause muscles to contract involuntarily and prevent them from relaxing normally. Elevated anti-GAD antibodies are found in up to 80% of people with SPS, according to research published in JAMA Neurology.

How the patient was treated

There is currently no cure for SPS, but treatment can help manage symptoms and slow disease progression.

The woman received intravenous immunoglobulin, an antibody treatment that can modify immune-system activity. She also received rituximab, a medication that targets specific immune cells and suppresses their activity.

Doctors also prescribed prednisone, gabapentin, diazepam and physical therapy to help relax the muscles affected by spasms.

Within a few days, the patient’s condition improved significantly. Before leaving the hospital, she could turn over in bed without assistance and fully flex her left hip and knee. She could also flex her right hip, bend her right knee to 110 degrees with assistance and stand with help.

Three months after discharge, she was able to stand independently and walk with the aid of a walker. Doctors began reducing her steroid dosage, while she continued taking diazepam and gabapentin, receiving monthly immunoglobulin and receiving maintenance doses of rituximab every six months.

Why stiff-person syndrome is difficult to diagnose

SPS is extremely rare. Estimates suggest that only about 1 to 2 people per million are affected each year, although more recent estimates indicate that the number may be higher.

Because the condition is rare and its symptoms can develop slowly, SPS is often difficult for medical professionals to recognize. It may be mistaken for mental health conditions, Parkinson’s disease or multiple sclerosis. It can also resemble dystonia, a neurological disorder that causes involuntary muscle contractions.

According to the case report, diagnosing SPS takes an average of about seven years after symptoms begin. The condition is most commonly diagnosed in people between 40 and 50 years old, although it can also affect older adults and children. About twice as many women as men are affected.

The mechanisms and progression of SPS remain incompletely understood, the authors noted.

Celine Dion has also shared an SPS diagnosis

Singer Celine Dion publicly shared her diagnosis of stiff-person syndrome in 2022 after canceling multiple shows in 2021 because of illness. She described experiencing severe and persistent muscle spasms and said the pain eventually became so intense that she was sometimes unable to walk.

This case was reported by Yadav, R., Abrol, N. and Terebelo, S. in “One in a million: A case report of stiff person syndrome,” published in Case Reports in Rheumatology in 2022.

Can you identify unusual medical conditions? Test your knowledge with our Dilemma Diagnosis quiz.