Ankylosing Spondylitis (AS) is a form of inflammatory arthritis primarily affecting the spine. It causes inflammation of the vertebrae, which can lead to severe, chronic pain and discomfort. Over time, this inflammation can result in new bone formation, causing the spine to fuse in a fixed, immobile position.
Early Historical Evidence
Evidence suggesting the presence of conditions similar to AS can be found in ancient human remains, long before formal medical descriptions. Skeletal findings with fused vertebrae have been interpreted as possible instances of AS in ancient populations. For example, early radiological studies of Egyptian mummies initially suggested AS in ancient pharaohs.
However, more recent imaging techniques, such as CT scans, have largely refuted these claims. These modern analyses indicate that spinal changes observed in royal Egyptian mummies were more consistent with diffuse idiopathic skeletal hyperostosis (DISH), a degenerative condition, rather than the inflammatory fusion characteristic of AS. While direct evidence of AS in ancient times remains debated, the existence of spinal fusion in prehistoric skeletons suggests such conditions have affected humans for millennia.
Initial Medical Recognition
The first documented medical description consistent with AS appeared in the late 17th century. In 1691, Bernard Connor, an Irish physician and anatomist, described a human skeleton with completely fused vertebrae. His account detailed a spine where the bones, ribs, and even the sacrum and iliac bones had become a single, continuous, inseparable structure. This precise description is widely considered the earliest pathological report of what is now known as AS.
Connor’s observation, published in Paris, marked a significant step in recognizing the pathological changes associated with the condition. At this stage, the condition was not yet formally named. The focus was on anatomical findings rather than a comprehensive clinical picture or its differentiation from other forms of arthritis.
Establishing the Disease Name
The late 19th century saw multiple independent descriptions that solidified the understanding and eventual naming of AS. In 1884, German neurologist Adolph Strümpell provided a detailed account of patients with progressive ankylosis of the spine and hip joints. His work contributed to the clinical identification of the disease.
Russian neurophysiologist Vladimir Bechterew, in 1893, described a disease characterized by spinal stiffness, dorsal kyphosis, and nerve root irritation. Though he initially considered it a neurological illness, his description helped differentiate it from other conditions. In 1898, French neurologist Pierre Marie further clarified the condition, noting an ascending pattern of spinal involvement, beginning in the sacroiliac joints and progressing upwards. These independent descriptions by Strümpell, Bechterew, and Marie led to the condition often being referred to as Marie-Strümpell disease or Bechterew’s disease, eventually consolidating into the name “Ankylosing Spondylitis.”
Evolving Diagnostic Understanding
Following its formal recognition, the diagnostic understanding of AS evolved. In 1961, the Rome criteria were introduced as the first formal diagnostic criteria, followed by the New York criteria in 1966. These criteria aimed to standardize diagnosis, incorporating clinical features like limited spinal mobility and radiological evidence of sacroiliitis (inflammation of the sacroiliac joints).
The modified New York criteria, established in 1984, further refined the diagnostic process, becoming the most widely used classification. These modified criteria consider factors such as lower back pain duration, improvement with exercise, limited lumbar spine range of motion, and limited chest expansion, alongside specific radiographic findings. The development of these criteria marked a shift towards a more precise and standardized approach to diagnosing AS, linking clinical observations with objective measurements and imaging.