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Hoffmann's sign is a test used in neurology to check if a person has pyramidal syndrome which results in motor and reflex disorders. What is Hoffmann's sign? How to interpret it? What to do if it is positive? Response elements.
Hoffmann's sign corresponds to flexion of the fingers after strong pressure on the major nail. We also speak of the Hoffmann reflex. This sign is named after the German neurologist Johann Hoffmann. We owe him not only the description of the Hoffmann sign but also that of Werdnig-Hoffmann disease (also called spinal muscular atrophy type 1). “Hoffmann's sign is part of the detailed neurological examination, even specialized when it is carried out by a neurologist.”, indicates Dr. Gérald Kierzek, emergency physician and medical director of TipsForWomens.
A positive Hoffmann sign (when finger flexion occurs) may be a sign of damage to the pyramidal pathway (nerve pathway that extends from the brain to the spinal cord) that controls voluntary motor skills.
What is the Hoffmann test?
The Hoffman test consists of exert strong pressure on the nail of the middle finger then release. If the release of this pressure causes the other fingers of the hand to flex, we say that Hoffman's sign is positive. In this case, we can suspect a pyramidal syndrome, which refers to all motor disorders linked to damage or dysfunction of the pyramidal pathway, responsible for voluntary movements.
Indeed, involuntary flexing of the fingers in response to certain triggers may be a sign of an underlying condition that affects the central nervous system.
How is the Hoffmann test performed?
The doctor who performs the Hoffman test first asks the patient to hold out his hand as if he were going to shake his hand, and to relax it so that the fingers are relaxed. The doctor then holds the patient's middle finger between his fingers, by the upper knuckle. He places one of his fingers on the nail of the middle finger before pressing on it for a few seconds then releasing it.
He repeats this pressure several times to ensure that the patient's hand reacts the same way each time. The test can be performed on the other hand to check if the sign is present on both sides of the body.
How to interpret the result?
If the patient's fingers flex when pressure on the middle fingernail stops, the Hoffmann sign is said to be positive.
If the patient's fingers do not flex when pressure is released on the major nail, the Hoffmann sign is negative. In this case, no damage to the central nervous system is suspected.
Positive Hoffmann sign: a symptom of pyramidal syndrome?
A positive Hoffmann sign may suggest a syndrome pyramidal which corresponds to a deficit in motor skills of the upper and lower limbs linked to damage to the pyramidal fasciculus. The main function of the pyramidal fasciculus is to ensure voluntary motor skills.
Mild damage to the pyramidal pathway often manifests initially as clumsiness. Affected people may have difficulty walking and tire more quickly than before… In the most serious cases, the damage is so severe that it causes paralysis which prevents walking.
Piriformis syndrome also manifests itself as stiffness caused by increased muscle tone. The patients' muscles are very tight, which makes their way of walking unnatural, a bit like robots.
What are the signs of pyramidal syndrome?
A motor weakness
Motor weakness, of variable intensity, may be indicative of pyramidal syndrome. Patients may complain of discomfort, heaviness, clumsiness, poor balance, or even paralysis. This weakness not only disrupts walking but can also have consequences on other common motor activities: running, climbing steps, getting up from a seat, carrying heavy loads, etc.
Limping intermittently
Patients may limp due to (painless) weakness in one or both lower limbs. This weakness generally occurs after a period of walking, disappears upon rest and reappears later.
Other symptoms of pyramidal syndrome
Patients may complain:
- contractures and/or stiffness which can be painful;
- phonation disorders and swallowing disorders (in case of bilateral involvement);
- urinary incontinence (the patient cannot stop urinating).
What are the causes of pyramidal syndrome?
Pyramidal syndrome can occur in all diseases that can affect the pyramidal tract:
- A cerebrovascular accident (CVA);
- Brain or spinal cord trauma;
- Multiple sclerosis (MS);
- A neurodegenerative disease;
- A tumor ;
- Familial spastic paraparesis (hereditary genetic disease).
How to treat pyramidal syndrome?
The treatment of pyramidal syndrome is primarily based on treatment of the cause (tumor, stroke, MS). And symptomatic treatment is generally associated to maintain or improve the motor functions of patients :
- Physiotherapy sessions;
- Drug treatment to combat hypertonia;
- Use of a cane to make walking easier;
- Botulinum toxin injection to reduce muscle tone and therefore muscle stiffness and contractions.
The progression of the disease will mainly depend on the treatment of the cause.
Hoffmann test: its diagnostic value is low
“Its sensitivity and specificity being relatively low, the Hoffmann sign is not part of the basic neurological examination, unlike the Babinski sign which is systematically looked for. A positive Hoffmann reflex and finger twitches suggest hypertonia but can occur in people without pathology”, commented Dr. Kierzek. The diagnostic value of this test is low compared to medical imaging examinations (brain scan, brain MRI, etc.).
The diagnosis of pyramidal syndrome is based on performing an imaging examination, including an MRI of the brain and/or spinal cord, to visualize the lesions of the pyramidal syndrome. Biological tests can be carried out in addition to look for the cause. For example, a lumbar puncture may be performed to look for inflammation of the nervous system characteristic of multiple sclerosis.
