Same family of conditions. Not the same attention.
Two questions, asked the same way of all five conditions. How much has been written about each one? And how long does it take a person to get the name?
How much has been written
Our searches returned 9,296 achalasia records indexed in PubMed, 2,891 of them from before 1990. The modern-name R-CPD search returned 89 records. It misses earlier reports published under different names. These are search results, not a complete census of research.
R-CPDA-CPDSpasmZenker'sAchalasia
Achalasia: 269
Zenker's: 88
Spasm: 117
A-CPD: 28
R-CPD: 28
PubMed-indexed records returned by the stated Europe PMC searches on 2026-10-08. The 2026 line is dashed because the year is not over. On a phone, scroll the chart sideways or use the year selector.Read all yearly values in a table
The final column makes differences between the all-time query and summed yearly queries explicit. The cause has not been verified; it may involve date indexing or records changing between requests. These differences are not assigned to a year.
How long it takes to get the name
Our search found dedicated diagnostic-delay studies for achalasia. For the other four, available figures came from small studies with other purposes, or for R-CPD, one clinic’s averages. Where nobody has measured something, the gap is left empty. “Not measured” here means no dedicated study was found in this search.
Thirteen patients, measured at treatment rather than diagnosis.
What was counted, and what was thrown out
Paper counts come from the Europe PMC search service, one search per condition per year, counting only papers indexed in PubMed. They were collected on 8 October 2026. The exact searches are listed below so anyone can repeat them.
The first R-CPD count was wrong. The original search included the bare abbreviation “R-CPD” and found 144 papers from 1990 on. Reading them showed that many had nothing to do with swallowing. Chemists use R-CPD for other things, including a kind of fluorescent particle, and 17 of those papers were from before the condition was even named. Conference abstract books also matched. Dropping the bare abbreviation and keeping only PubMed papers left 89, all from 2019 on.
A-CPD and R-CPD overlap. The phrase “cricopharyngeal dysfunction” also appears in every paper about retrograde cricopharyngeal dysfunction, so the A-CPD search excludes those papers to avoid counting them twice. It still includes papers about swallowing problems after strokes and other nerve conditions, which use the same words.
Diagnosis times were read by hand. Europe PMC was searched for each condition together with “diagnostic delay”, “time to diagnosis”, “misdiagnosis” or “misdiagnosed”. That returned 389 different PubMed papers, most of them single case reports. Every abstract with a number near those words was checked in the original research pass. The diagnostic-delay review is separate from the refreshed paper counts; it is not a systematic review. Each displayed estimate links to its source.
The refreshed spasm search includes “distal esophageal spasm” and “hypercontractile esophagus”. R-CPD counts remain restricted to modern names: older inability-to-belch reports exist, including reports from 1987, 1989 and 2001 discussed in Lechien and colleagues’ review. Adding broad inability-to-belch terms also finds postoperative problems unrelated to R-CPD, so those results are not presented as R-CPD research. No records under the modern name before 2019 does not mean no earlier research.
Searches used for this snapshot
Achalasia
("esophageal achalasia" OR "achalasia cardia") AND SRC:MED
Zenker's
("Zenker diverticulum" OR "Zenker's diverticulum") AND SRC:MED
Spasm
("diffuse esophageal spasm" OR "distal esophageal spasm" OR "jackhammer esophagus" OR "hypercontractile esophagus") AND SRC:MED
A-CPD
("cricopharyngeal achalasia" OR "antegrade cricopharyngeal" OR "cricopharyngeal dysfunction") NOT ("retrograde cricopharyngeus" OR "retrograde cricopharyngeal") AND SRC:MED
R-CPD
("retrograde cricopharyngeus" OR "retrograde cricopharyngeal") AND SRC:MED
What not to read into this
A paper count measures attention, not quality. Thousands of achalasia papers include many single case reports. R-CPD’s 89 include meta-analyses. The comparison is sensitive to terminology, indexing and search coverage. It cannot by itself measure research quality or clinical attention.
The R-CPD 17 years is two averages, not a measured wait. It is the gap between the average age when symptoms began and the average age at diagnosis in one French clinic. People who reach a specialist clinic may have waited longer than most.
The achalasia studies disagree. The median wait was 24 months in Italy and the mean was 4.7 years in Germany. These studies involved different patients and methods, so the results are not directly comparable. A mean is more affected by unusually long waits than a median.
2026 is not finished. The last point on the chart covers part of the year.