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Study by Pera doctor-duo goes from just published to ‘citation classic’
View(s):- ‘Neurotoxic effects of organophosphorus insecticides: An intermediate syndrome’ in NEJM in 1987
By Kumudini Hettiarachchi
Never in their wildest dreams did two medical specialists based in Peradeniya think that a humble study of theirs would reach such international heights – achieving the rare distinction of exceeding 1,000 citations, 1,054 citations to be exact.
“It was a real ‘gamey wedak’,” laughs one of the researchers, Dr. Lakshman Karalliedde, underscoring that there was no outside funding and no foreign collaboration for this study. They used their own funds, unlike these days.
Prof. Nimal Senanayake
The other researcher in this scholarly article on ‘Neurotoxic effects of organophosphorus insecticides: An intermediate syndrome’ published in the New England Journal of Medicine (NEJM) in 1987 is Prof. Nimal Senanayake. (See box for abstract)
With insecticides being widely used in vegetable and fruit cultivations in Sri Lanka, the study by Physician Prof. Senanayake and Anaesthetist Dr. Karalliedde, both attached to the Peradeniya Teaching Hospital at that time, had revolved around the life-threatening toxicity caused by exposure to these insecticides.
Such insecticide poisoning could impact different parts of the human body including the cardiovascular system (heart and blood vessels); the central nervous system (brain and nerves); the gastrointestinal system (digestion tract); the genitourinary system (kidneys and urinary tract); musculoskeletal system (bones, muscle, cartilage and more); and respiratory system (lungs, airways and more).
Earlier the profile of organophosphate toxicity was believed to be acute, but the groundbreaking findings of Dr. Senanayake and Dr. Karalliedde brought in a different dimension of ‘intermediate’ to such poisoning.
Explaining the medical technicalities, Dr. Karalliedde says that in the 1980s, studies on the neuromuscular junction were mainly by anaesthesiologists. They were observational studies as there was not a single nerve muscle stimulator available in Sri Lanka to make quantitative/qualitative assessments.
The Sunday Timesunderstands that the neuromuscular junction is a specialized ‘synapse’ that connects motor neurons (nerve cells) and skeletal muscle fibres. A synapse is a structure where two neurons or a neuron and a muscle/gland cell, meet to communicate by transmitting nerve impulses via chemical (neurotransmitters) or electrical signals. These microscopic junctions are crucial for the body’s functions.
Dr. Lakshman Karalliedde
According to Dr. Karalliedde, the key determinant to differentiate the muscle paralysis they encountered in some cases of organophosphorus insecticide poisoning was to identify whether the paralysis differed in a measurable manner in different cases.
Describing how he travelled to the United Kingdom and obtained a used nerve muscle stimulator from an English colleague, he says that it made all the difference, as the paralysis observed was distinct/different.
A retired Senior Assistant Librarian/Medical who has served at the Medical Library of the Faculty of Medicine, University of Peradeniya, for nearly three decades, Sriyani Perera, has confirmed that the article in the NEJM has surpassed the “milestone” of 1,000 citations.
“A search conducted by me in the Google Scholar database on 8th March 2026 indicates that the article has received 1,054 citations,” she states following an independent verification. Such counts may continue to change as additional publications cite the work.
Giving a librarian’s view of the significance of the 1,000-Citation Mark, Ms. Perera states that in the landscape of scientific research, citation counts are among the most widely used indicators of how strongly a piece of work has influenced subsequent inquiry.
“Exceeding 1,000 citations for a single scholarly article in biomedical research is considered a distinguished milestone, signifying that the work has moved beyond merely being ‘published’ to becoming a foundational, high-impact pillar of scientific knowledge. Such papers are often regarded as ‘citation classics’ or ‘outliers’, as only a tiny fraction of research papers ever reach this threshold,” she says.
Thus, the authors of this article, published in 1987, in the NEJM – widely regarded as one of the most authoritative journals in clinical medicine and noted for holding the highest h-index in the field – should be congratulated for their outstanding achievement, according to her.
Ms. Perera states: “In an era when scientific literature is expanding rapidly – sometimes accompanied by studies of uneven quality – the sustained citation of a single work justifies that it has provided reliable, meaningful and influential evidence for the research community. It signifies that the work has been repeatedly consulted, trusted and built upon by researchers across the world, reflecting its originality, methodological rigor and enduring relevance to human health.
“The article demonstrates first-of-its-kind research findings and provides comprehensive guidance to new researchers in the field, with a focus on real-world clinical scenarios. As reported in the article, the term ‘Intermediate Syndrome’ appears to have been first coined by the authors during their study in 1987, a concept that has remained in use over the past four decades.
“This further underscores the originality of the work, its reliability in laying the groundwork for emerging research and its long-term relevance in bridging multiple research projects and generations of scientists.
“At this juncture, it is therefore both gratifying and a source of pride that this highly cited contribution originated from local scholarship, produced by two authors from our own country. Such international recognition demonstrates the remarkable capacity of local scholarship to resonate across borders and contribute meaningfully to the global advancement of medical knowledge.”
| The Intermediate Syndrome Here is the abstract of the article of Prof. Nimal Senanayake and Dr. Lakshman Karalliedde, published in March 1987 in the NEJM, aweekly general medical journal based in Waltham, Massachusetts, United States of America. “The neurotoxic effects during the cholinergic phase of organophosphorus insecticide poisoning and delayed neurotoxic effects appearing two to three weeks later are well recognized. We observed 10 patients who had paralysis of proximal limb muscles, neck flexors, motor cranial nerves, and respiratory muscles 24 to 96 hours after poisoning, after a well-defined cholinergic phase. (A ‘cholinergic phase’ is a potentially life-threatening medical emergency resulting from the overstimulation of nicotinic and muscarinic receptors at the neuromuscular junctions and synapses.) “The compounds involved were fenthion, monocrotophos, dimethoate, and methamidophos. Four patients urgently required ventilatory support. The paralytic symptoms lasted up to 18 days. “A delayed polyneuropathy later developed in one patient. Three patients died. Electromyographic studies showed fade on tetanic stimulation, absence of fade on low-frequency stimulation and absence of post-tetanic facilitation, suggestive of a postsynaptic defect. “This neuromuscular junctional defect may have been the predominant cause of the paralytic symptoms, with neural and central components contributing to various degrees. Our patients appeared to have a distinct clinical entity (a so-called intermediate syndrome) that developed after the acute cholinergic crisis and before the expected onset of the delayed neuropathy.”
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