Tromner Sign
Introduction
The Trömner Sign, also known as the "finger flexor phenomenon," was first described in 1912 by Ernest Trömner (1868–1930) from Saxony.[1]
Purpose
Trömner sign involves flexion of the thumb and index finger when the examiner taps or flicks the volar distal phalanx of the middle finger, which is slightly flexed and held by the examiner. It is an alternative to Hoffmann’s sign for testing the finger flexor reflex. A positive Trömner sign, like Hoffmann's, indicates a corticospinal tract lesion (upper motor neuron) above the C5 or C6 spinal level, especially if seen unilaterally.[2]
Technique
These steps should be followed when performing the test:
1. Positioning the Hand:
The examiner holds the patient's hand with the fingers semi-flexed.
The middle finger (or index finger) is stabilized just proximal to the distal interphalangeal (DIP) joint.
2. Tapping:
The examiner taps or flicks the volar (palmar) surface of the patient's distal middle or index finger.
3. Observation:
A positive Tromner sign is indicated by involuntary flexion of the thumb and index finger.
4. Interpretation:
The presence of this reflex typically suggests an upper motor neuron lesion, often seen in cases of spastic paralysis or corticospinal tract dysfunction.[3][1]
This video shows how to use the test
Evidence
The Trömner sign shows high sensitivity (94%) and specificity (93%), highlighting its effectiveness in both confirming and excluding diagnoses of degenerative cervical myelopathy (DCM).[3]
Another study found a high occurrence of positive Trömner signs in patients with cervical cord compression who have not yet shown symptoms. This suggests that the Trömner sign could be valuable for the early detection of these patients.[5]
Trömner Sign vs Hoffmann’s sign
The Hoffmann's and Trömner signs are two neurological tests used to assess upper motor neuron function, but they respond differently to stimulation due to the anatomy of the fingers.
The Hoffmann's sign is typically elicited by nipping or flicking the nail or the tip of the middle or ring finger. In contrast, the Trömner sign is triggered by tapping the skin on the underside of the distal phalanx of the middle finger. It’s important to note that the nail itself has no nerve endings, which means that when the Hoffmann's sign is tested through the nail, the stimulation may not adequately activate the underlying nerve endings in the nail bed. This could reduce the sensitivity of the Hoffmann's sign.[6]
References
- ↑ 1.0 1.1 Maranhão-Filho P, Correa RB. Babinski's hand sign: many have tried…. Arquivos de neuro-psiquiatria. 2018 Oct;76(10):716-9.
- ↑ Larner AJ. A dictionary of neurological signs. New York, NY: Springer New York; 2006 Jan 1.
- ↑ 3.0 3.1 Jiang Z, Davies B, Zipser C, Margetis K, Martin A, Matsoukas S, Zipser-Mohammadzada F, Kheram N, Boraschi A, Zakin E, Obadaseraye OR. The value of Clinical signs in the diagnosis of Degenerative Cervical Myelopathy-A Systematic review and Meta-analysis. Global Spine Journal. 2024 May;14(4):1369-94
- ↑ Youtu.be. Available at: https://youtu.be/kE40_tx2SeI (Accessed: September 22, 2024).
- ↑ Chaiyamongkol W, Laohawiriyakamol T, Tangtrakulwanich B, Tanutit P, Bintachitt P, Siribumrungwong K. The significance of the trömner sign in cervical spondylotic myelopathy patient. Clinical spine surgery. 2017 Nov 1;30(9):E1315-20.
- ↑ Galav A. A clinico-radiological study of diagnostic accuracy of special clinical tests in diagnosing compressive myelopathy in patients of early cervical spondylitis symptoms along with its radiological correlation. Romanian Neurosurgery. 2022 Mar 15:88-91.