His name in medicine is linked to Redlich-Flatau syndrome, Flatau-Sterling torsion dystonia (type 1), Flatau-Schilder disease, and Flatau's law.

Flatau dealt with the diagnosis and treatment of diseases of the brain, treatment of muscle diseases, child neurology, peripheral nerve surgery, anatomy of the nervous system, histopathology of the nerve tissue, experimental oncology, neurophysiology, and nervous system pathophysiology.

The most comprehensive are biographies written in Polish by his pupil and subsequent professor of neurology in the postwar Poland, Eugeniusz Herman.

In a review, Sigmund Freud wrote: "The plates with their clarity deserve to be called excellent educational material, suitable as an utterly reliable reference.

A schematic plate in the beginning gives an overview of our knowledge on the fibre pathways in the CNS, incorporating the accounts of Mendel, Bechterew and Edinger and continuing with the differing views on the structure of nervous tissue of Camillio Golgi and Santiago Ramón y Cajal.

With the Berlin neurobiologist Johannes Gad, Flatau performed experiments on dogs and criticized the Bastian-Bruns law concerning the loss of function following spinal cord injury (1893).

For this work he received a PhD in medical sciences in Moscow in 1899 (dissertation Zakon ekstsentricheskago raspolozheniia dlinnykh putei v spinnom mozgu).

Together with Alfred Goldscheider, he worked on the structure of nerve cells and their changes under mechanical, thermal, and toxic influences.

This work, in which the normal and pathologic anatomy of the V, VII, and VIII (cochlear) cranial nerves was included, created much discussion and was adversely criticized by Franz Nissl, who opposed the neuron theory.

[29] He modified Golgi's method of tissue staining[30] and on the basis of studies of physiological effects of transverse intersection of the spinal cord in dogs carried out together with Johannes Gad, he provided criticism of the Bastian–Bruns sign of disappearance Patellar reflex as a result of this treatment (1896).

In 1895 and 1896, Flatau and Jacobsohn received 1500 marks from duchess Louise von Bose, probably to develop presentation for an international medical congress in Moscow in 1897.

[31] In 1910 and 1911, he wrote three chapters on tumors of the brain and spinal cord for the two volumes of the handbook edited by the Berlin neurologist Max Lewandowsky.

[32] Together with the Warsaw surgeon Bronislaw Sawicki, he published a work on surgery of the spinal-cord cysts and treatment of tumors of the spine, in which he pointed out histopathological issues important for the surgical procedure.

In the same year, Theodor Ziehen and Hermann Oppenheim published a paper claiming that dystonia is related to a disease of the muscles.

[36] In 1927, Flatau, independently of Emil Redlich in Vienna, described the first cases of encephalomyelitis epidemica disseminata (Flatau-Redlich disease).

In a review of the historical background of general aspects of the headaches, Isler and Rose say, "His unique monograph of 1912, Die Migrane, contains a thoroughly structured survey of most earlier authors, precise clinical observations, a critical evaluation of pathophysiology, and uncritical opinions on treatment, including arsenic cures.

Nevertheless, great progress characterizing the development of neurology in the second half of the nineteenth century is visible in the field of research into migraine as well.

[21][41] Irena Solska, famous Polish actress, describes in her memoirs that playing Maria, a mad wife in nondivine comedy of Zygmunt Krasinski around 1920, she visited the psychiatric hospital (ward) of Edward Flatau.

At the bedside of each patient, Flatau discussed their cases, he listened to the voice of everyone, even the youngest doctor ... As a teacher and a boss, he was deeply attached to each and every one who worked with him.

Flatau's law, originally published in German, was reprinted in Polish in the journal Nowiny Lekarskie together with the basic introduction.

[21] According to the comments of Henryk Higier in 1932,[53][54] "Flatau being convicted of the shameful behavior of the German occupying forces during the World War I stopped his friendly relations with Germany, to which scientist he felt deep affection, and moved entirely his scientific affinity towards medical sciences in France ..." .

As Poland was under occupation in that time, this society played an important role in re-establishing Polish science in the years to come.

In the early 20th century, after settling in Warsaw, Flatau established in his private apartment, microscopy laboratory in the building where the fashion house of Herse was located on Marszałkowska 150 street.

The anecdote about this laboratory is: "[A] carriage would take us to building on Marszalkowska Street, the same building where were mannequin ladies stood in shopping windows of House of Fashion of Boguslaw Herse (...) In this house lived, on the first floor, my uncle Edward Flatau, who – just like my father – was a neurologist and psychiatrist (...) There was a St. Bernard dog that had its idiosyncrasies.

In the long, narrow room of the apartment stood, preserved in alcohol and covered, brains of animals and humans that uncle studied.

St. Bernard looked at my uncle with reproach and would leave the room in protest against these threats..."[3] Subsequently, this laboratory moved on Jerozolimska Avenue 85 under auspices of the Psychological Society.

In October 1911, Flatau donated to the Warsaw Scientific Society his neurological laboratory, along with the entire inventory and allowance of 2,000 rubles.

In that time (1911), the Warsaw Scientific Society received as a gift from Józef Potocki, a house on Śniadeckich 8, where the laboratory was located.

At the end of 1918, Kazimierz Białaszewicz, along with Edward Flatau and Romuald Minkiewicz, head of just created Department of General Biology (Zakład Biologii Ogólnej) applied to the board of the Warsaw Scientific Society with an initiative to separate these three laboratories and create an organization under the name of "Institute of Experimental Biology.

[58][59][60] At his grave, Dr. A. Goldman said:[60] "reticent in colloquial conversations, strong in resolving professional and academic difficulties, Edward Flatau died as a result of the suffering that he recognized himself and during the course of his illness he carefully and stoically made notes about its progress (...).