A small (70mm wide) instrument consisting of a thin octagonal disc of light blue plastic with narrow metal prongs of 10mm in length emerging from each side. One side has a single prong, the remaining seven have two. Adjacent to each side, moulded into both faces, are numbers indicating the distance between the prong. These distances are 1, 20, 15, 14, 13, 12, 11, 10 and 9. (The single rod, labelled “1”, is also 20 mm from the closest prong to its right.)
Accession Number: 2024.med.51
Alternative Name: Two-Point Discrimination Test
Primary Materials: Plastic, Stainless Steel
Moulded into the upper surface of the disc: “MACKINNON-DELLON// DISK-CRIMINATOR TM”
Dimensions (cm): Height = .3, Width = 7, Length = 7.
This instrument is used to assess nerve sensibility in patients that have suffered nerve damage. The test is used to determine the minimum distance at which a patient can distinguish between two different points placed against the skin. Tests can be given in a moving or static format (see Dellon, Mackinnon, and McDonald 1987).
This instrument was designed to provide an improved and standardized form of a long extant neurological test.
This artifact is intact and in good cosmetic condition. Some of the pins are slightly bent. The moulded letters and numbers are slightly discoloured by dirt from handling. The metallic paint that originally covered these details has almost completely worn away. This item is one part of a two-disc set.
Associated Instruments:
Manufacturer: Neuroregen, LLC, Bel Air, Maryland, USA
Date of Manufacture: c. 1990s
This diagnostic tool was used by Dr. Peter Kopplin, professor emeritus of the University of Toronto Faculty of Medicine. He donated it to the collection on 3 October, 2024.
Susan E. Mackinnon and A. Lee Dellon (1985) “Two-Point Discrimination Tester.” The Journal of Hand Surgery (American Ed.) 10, no. 6: 906–7.
A. Lee Dellon, Susan E Mackinnon, and Page McDonald Crosby (1987). “Reliability of Two-Point Discrimination Measurements.” The Journal of Hand Surgery (American Ed.) 12, no. 5: 693–96.
Susan Mackinnon and A. Lee Dellon (1991). Diagnostic and sensory re-education device (Canadian Patent CA1282660C). Canadian Intellectual Property Office. (Digitized by Google Patent).
The set of two disks was sold by the following supplier for $135 US:
US Neurologicals LLC. “Dellon-McKinnon Disk-Criminator.” (Archived 9 October, 2024).
This device is a modification of the “DeMayo two-point discrimination device” marketed by the Padgett Instrument Company. It resembles that instrument save for several improvements including longer prongs, which prevents a third prong from contacting the skin when the instrument is held at an acute angle, and a textured patch to prevent the instrument from slipping in the hand. (See Macinnon and Dellon 1985).
This device was developed by Susan E. Mackinnon of the University of Toronto Division of Plastic Surgery and Sunnybrook Hospital, along with A. (Arnold) Lee Dellon of the Curtis Hand Center and Division of Plastic Surgery, Johns Hopkins Hospital.
This artifact is one disc of a set of two. The other, made in a deeper blue plastic, comes in finer (1 to 8mm) increments.
- Donated to UTSIC