Keywords: Reflex - Babinski sign - motor disorders
Palavras-chave: Reflexo - sinal de Babinski - transtornos motores
On February 22nd , 1896, it was a cold Parisian Saturday. The temperature ranged from −0.3°C to 7.6°C
but it was not raining[1 ]. In a lively meeting at the Société de Biologie , the 38-year-old French-naturalized Polish neurologist, Joseph Jules François Felix
Babinski, read a 28-line text named “Le réflexe cutané plantaire dans certaines affections
du système nerveux central”[2 ]. In this lecture, Babinski presented, for the first time, an objective sign “that
allows the distinction between organic neurologic disorders and those of functional
or hysteric origin”[3 ]. In the more than 120 years that followed this day, several neurologists have attempted
to find an equivalent sign in the fingers[4 ]. The purpose of this manuscript is to highlight some of these attempts.
Carpometacarpal reflex – von Bekhterev
In 1903, the Russian, Vladimir Mikhailovich von Bekhterev (1857-1927), emphasized
that his upper limb test, a stimulus made to the tendons covering the back of the
hand in the carpus and the beginning of the metacarpal area, promoting a flexor response
of the fingers[5 ], also indicated – as Babinski had done in relation to the hallux – the differentiation
between an organic versus functional paralysis[6 ] ([Figure 1 ]).
Figure 1 VM Bekhterev and his carpometacarpal reflex article[5 ].
In 1908, Louis Jacobsohn-Lask (1863-1941), a German neurologist ([Figure 2 ]), described a similar reflex to von Bekhterev, and considered:
“…similar to Babinski's… the finger flexion reflex appears rather constantly in cases
of spastic paralysis of the upper limb of a cerebral character…”
[7 ]
Figure 2 Louis Jacobsohn-Lask and the Fingerbeuge reflex artice[7 ].
Due the great similarity with the von Bekhterev method, the two-finger flexion reflex
began to be called the Bekhterev-Jacobsohn reflex.
Hoffmann's reflex phenomenon – the Hoffmann sign
Around 1910, Johann Hoffmann (1857-1919) was honored by his pupil, Hans Curschmann
(1875-1942), when he quoted Hoffmann's name in a method of investigating the fingers
flexor reflex – “ Hoffmann's Sign” or “Hoffmann's Reflex”. In the technique to elicit
this, the examiner holds the median phalanx of the examined middle finger between
his own second and third fingers and promotes a rapid and forced stimulation – flicking
and sudden release – of the flexed terminal phalanx of the retained finger ([Figure 3 ])[8 ]. This reflex is present when the patient's other fingers – including the thumb –
flex.
Figure 3 Johann Hoffmann (left), Hans Curschmann, and the method of examination.
The Hoffmann reflex acquired enormous popularity among American neurologists. For
the sake of truth, Curschmann did not think it had significance as the “Babinski's
upper extremity” sign[9 ]. However, many textbooks and articles have come to consider it as a clear sign of
injury to the pyramidal path, “with the same significance as Babinski's sign”[8 ].
The fingers phenomenon – Gordon's sign
In 1911, Alfred Gordon described “Le phénomène des doigts” (the fingers phenomenon),
republished in French the following year[10 ]. In hemiplegia and monoplegia of cerebral origin, the compression of the radial
face of the pisiform bone of the paralyzed segment promoted the extension of the fingers,
sometimes in a fan ([Figure 4 ]).
Figure 4 Sign of the fingers in patients with pyramidal pathway impairment. Compression of
the projection of the radial side of the pisiform bone, avoiding compression of the
dorsal side of the hand (A). The fingers extend, sometimes in a fan (B). The sensitivity
of the signal increases when the test is repeated several times[10 ].
According to Gordon, when there is impairment of the pyramidal pathway, this signal
has the same connotation as the Babinski sign[10 ].
Finger flexor phenomenon – the Trömner Sign
In 1912, Ernest Trömner (1868-1930), from Saxony, described a finger reflex which
was named the “fingerbeugephänomen” (finger flexor phenomenon) ([Figure 5 ]). The patient keeps his fingers semi-flexed, and the examiner “taps” with his own
fingers on the volar surface of the patient's middle or index finger. The abnormal
reflex is present when all fingers flex, including the thumb. Trömner himself stated
that he only elicited this reflex in cases of spastic paralysis of the arm:
“… a pathognomonic finger reflex… a reflex of the arm, analogous to the Babinski,
which is as pathognomonic for motor conduction abnormalities above the spinal centers
innervating the arm, as the Babinski phenomenon is for the leg…”
[11 ]
Figure 5 Ernest Trömner (left), “Fingerbeugephänomen” description, and the method of examination[9 ].
In 1926, Sterling[12 ], described a maneuver very similar to that of Trömner in pyramidal lesions, aiming
at the same goal.
The upgoing thumb sign – Hachinski sign
In 1992, in a letter addressed to the Editor, Vladimir Hachinski, a neurologist of
Ukraine origin, described “the upgoing thumb sign”[14 ], considering it to be “Babinski's equivalent of the hand”. In 2017, Hachinski et
al. stated:
“… In a considerable proportion of patients with neurologic diseases, the thumb contralateral
to the hemisphere or brainstem side involved, showed an upgoing thumb while keeping
the palm facing at the level of the shoulder, corresponding to an upgoing toe sign
(Babinski sign) ”[15 ].
Several authors have expressed ambiguity in this respect. Tamm[16 ], for example, suggested the name: Babinski-Hachinski sign, while Fuller et al.[17 ], after evaluating 60 hands of normal individuals (hospital staff), found a positive
upgoing thumb in 62% to 88% of the cases. This also generated a letter to the Editor
entitled: Babinski Yes, Hachinski No!
DISCUSSION
Since Babinski, the lower extremity has been the most exploited anatomic region for
the majority of reflex hunters. Until recently, some predictably directed their efforts
toward the upper extremity in search of a reflex analogous to the hallux extension[15 ],[18 ].
The plantar response to plantar stimuli is considered a superficial reflex, like the
cremasteric reflex (described by M. Jastrowitz in 1875), and the abdominal reflex
(described by Ottomar Rosenbach in 1876), all being affected by an upper motor neuron
disorder (not necessarily a lesion). The Babinski sign is only a small fragment of
the mass reflex (withdrawal reflex) of the leg, with which the animal reacts to stimuli
of many kinds, when the pyramidal tract is impaired. The upgoing toe reflex is regarded
anatomically as an extension of the big toe but physiologically it is part of a flexor
reflex, apparently disinhibited by loss of upper motor neuron control, and its receptive
field may extend, in some instances, to the leg or thigh[19 ]. The abnormal pyramidal tract reflexes in the upper extremities are less constant,
more difficult to elicit, and less definitively diagnosed than those found in the
lower extremities[8 ]. According to van Gijn[20 ], two aspects justify the impossibility of obtaining a finger sign like that found
in the feet, with respect to impairment of the pyramidal pathway. There is no involuntary
action in spinal flexion synergy comparable to the lower limbs, and besides, the thumb
is far from being analogous to the big toe!
