Superficial physiological reflexes
Assessment of superficial reactions is of paramount importance for topographical diagnosis. To elicit them, the physician uses a blunt object, such as the handle of a neurological hammer or the reverse end of a needle, applying light stroking stimuli.
- Abdominal reflexes are divided into three levels. The upper one is tested by stroking along the costal margin, the middle one horizontally at the level of the umbilicus, and the lower one parallel to the inguinal fold, 1–2 centimeters above it. Normally, contraction of the abdominal wall muscles is observed on the side of stimulation.
- Plantar reflex is elicited by stroking the outer edge of the foot from the heel toward the toes. A healthy response is plantar flexion of the toes. The arc is mediated at the level of segments L5–S2.
- Cremasteric reflex is assessed exclusively in males by stroking the inner thigh, which leads to contraction of m. cremaster and elevation of the testicle (closure level L1–L2).
- Anal reflex requires light stimulation of the skin and mucous membrane around the anus with a thin blunt object, in response to which the sphincter (m. sphincteris ani) contracts. It is integrated at the level of the III–IV sacral segments. The absence of these reactions directly indicates damage to the spinal reflex arc at the corresponding level.
Examination of muscle clonus
When a patient exhibits increased reflex excitability (hyperactive tendon responses), the physician must check for the presence of clonus—pathological rhythmic and repetitive muscle contractions.
- Patellar clonus. The patient lies supine with legs fully extended. The clinician grasps the patella between the thumb and index finger, abruptly pushes it downward, and firmly holds it in this position. In pathology, rhythmic up-and-down movement of the patella occurs due to spastic contraction of the quadriceps femoris muscle.
- Ankle clonus. The patient lies supine, with the examined leg flexed at the hip and knee joints. The physician performs a sudden passive dorsiflexion of the patient's foot and holds it. A positive sign is manifested by rhythmic plantar flexion driven by the gastrocnemius and soleus muscles.
Extensor pyramidal signs
The appearance of pathological reflexes is a key marker of an upper motor neuron (pyramidal tract) lesion. In the lower extremities, they are divided into flexor and extensor signs. The earliest and most reliable extensor symptom is the Babinski reflex (Babinski reflex).
- Technique for eliciting: The physician runs a blunt instrument along the lateral edge of the plantar surface of the foot from the heel toward the base of the toes.
- Response: There is slow tonic extension (dorsiflexion) of the first digit (great toe), while the remaining digits (second through fifth) fan out laterally.
- Clinical significance: In infants up to 1–1.5 years of age (sometimes up to 2 years), this sign is an absolute physiological norm. This is because in early childhood, the myelination of the corticospinal tract is not yet complete. In adults and children over two years of age, its presence is strictly pathological.
Flexor pyramidal signs
This group of symptoms also indicates dysfunction of the pyramidal tract and can be tested in both the lower and upper extremities.
- Rossolimo reflex (Rossolimo reflex). A crucial flexor sign in the foot. The physician delivers short, brisk taps (percussion) with the tips of their fingers to the plantar side of the distal phalanges of digits II–V of the patient. In lesions of the central motor neuron, rapid plantar flexion of these fingers occurs.
- Trömner reflex (Trömner reflex). The upper extremity equivalent of the previous symptom. The patient's arm is relaxed, with the hand hanging freely (or supported by the physician by the fingers). The clinician delivers a sharp tap (flick) from bottom to top on the palmar side of the terminal phalanx of the middle (third) finger. A positive response is rapid flexion of the distal phalanx of the thumb and other fingers of the hand. Indicates central paresis at the level of the cervical enlargement of the spinal cord or higher. Note: can be weakly elicited in completely healthy individuals with heightened nervous excitability.
- Hoffmann reflex. Also tested in the upper extremity. The physician performs a pinching stimulus on the nail plate of the third finger, which causes a corresponding flexion of the terminal phalanges of the hand.
Instrumental and neuroimaging diagnostics
Modern hardware methods are used to confirm the level of the lesion and assess the state of the nerve pathways.
- To assess conductivity along the corticomuscular pathway, electromyography (EMG) is used, and evoked motor responses are analyzed using transcranial magnetic stimulation of the cerebral cortex.
- For precise visualization and localization of the pathological process within the structures of the brain or spinal cord, X-ray computed tomography (CT) and magnetic resonance imaging (MRI) are used.
Briefly: answers to topical questions
At which spinal cord levels are the upper, middle, and lower abdominal reflexes mediated?
The upper abdominal reflex is mediated at the level of the thoracic segments of the spinal cord (T7–T8). To elicit it, a stroking stimulus is applied with a blunt object along the costal margin (3–4 fingers above the umbilicus), leading to contraction of the abdominal wall muscles on the side of stimulation. The exact closure levels of the reflex arcs for the middle and lower abdominal reflexes are not specified in the sources.
What extensor pyramidal signs exist in the lower extremities, aside from the Babinski reflex?
In addition to the Babinski reflex, extensor pathological reflexes in the lower extremities include the Oppenheim and Gordon signs.
- Oppenheim sign — elicited by running the thumb down the anterior surface of the tibia from top to bottom, which leads to extension of the big toe.
- Gordon sign — manifested by reflex extension of the first digit of the foot in response to squeezing the calf muscle.
These reflexes indicate a lesion of the upper motor neuron (pyramidal tract).
What are the main clinical symptoms characteristic of parkinsonism syndrome?
The main clinical symptoms of parkinsonism syndrome are motor disorders that constitute the classic triad.
- Akinesia (hypokinesia, bradykinesia) — slowing of everyday actions, difficulty initiating movements, and a mask-like face (hypomimia).
- Rigidity — pathological increase in muscle tone.
- Tremor — resting tremor with a frequency of 4–8 Hz, which disappears during purposeful movements and sleep (the "pill-rolling" phenomenon is typical).
In advanced stages, these symptoms are joined by postural instability, dysarthria, drooling, and gait disturbances (shuffling gait with small steps).
Damage to which brain structures leads to the development of parkinsonism syndrome?
The development of parkinsonism syndrome is caused by damage to the basal ganglia and functionally related structures.
- Substantia nigra (substantia nigra) — the loss of melanin-containing neurons in its pars compacta (pars compacta) serves as the primary anatomical substrate of the disease, leading to dopamine deficiency in the nigrostriatal synapses.
- Subcortical structures and brainstem nuclei — are also involved in the degenerative process (including other monoaminergic nuclei).
- Cerebral cortex and olfactory bulbs — are affected in widespread degeneration.
For quick memorization of cutaneous reflex levels: Cremasteric — L1–L2 (lumbar), Plantar — L5–S2 (sacral junction), Anal — S3–S4 (lower sacrum).
Class and exam questions
How to properly elicit superficial abdominal reflexes?
It is necessary to apply a light stroking stimulus with the blunt end of a neurological hammer. For the upper reflex, the line is drawn along the costal margin; for the middle reflex, horizontally at the umbilical level; for the lower reflex, parallel to the inguinal fold.
What does the absence of the anal reflex indicate?
Loss of this physiological response indicates damage to the spinal reflex arc at the level of the third and fourth sacral segments (S3–S4).
In which cases is the Babinski reflex considered normal?
In adults, this sign is strictly pathological and indicates damage to the upper motor neuron. However, in infants up to 1–2 years of age, it is considered normal due to incomplete development and unfinished myelination of the corticospinal tract.
What is the difference between Rossolimo's and Trömner's pathological reflexes?
Both belong to flexor pyramidal signs, but the first is tested on the lower extremity (striking the distal phalanges of digits II–V of the foot), while the second is tested on the upper extremity (flicking the terminal phalanx of the third finger of the hand).
What else to study on this topic
- Topical diagnosis of spinal cord lesions by segments (from L1 to S4).
- Mechanisms of muscle clonus formation in hyperreflexia.
- Age-related stages of pyramidal tract myelination in infants.
- The role of electromyography (EMG) and magnetic stimulation in assessing the corticomuscular pathway.
- Comparative characteristics of CT and MRI in searching for the upper motor neuron lesion site.
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