Positive signs of functional motor, sensory and gait disorders
| Clinical sign | Estimated specificity (CI) | Estimated sensitivity (CI) | Positive predictive value (CI) | Negative predictive value (CI) | Description | Comment | References |
|---|---|---|---|---|---|---|---|
| Motor | |||||||
| Validated | |||||||
| Hoover sign | 99% (95.7 to 99.9) | 94% (85.8 to 97.3) | 99% (92.8 to 99.9) | 96% (91.3 to 98.4) | A:P supine, E hand under paretic leg (under heel): P exerts max force downward B:Same but P exerts max force upward with contralateral leg (against E resistance) Comparison of felt pressure in E hand under paretic side heel Hoover+if strength in condition B>A Hoover— if strength B≥A | Can only be applied when a significant proximal leg weakness is present. Caution when coexisting comprehension/attention deficit or cortical neglect or pain | Stone et al21, Sonoo 14, Tinazzi et al15, McWhirter et al13, Ziv et al19 |
| Abductor sign | 100% (77.1 to 100) | 100% (75.9 to 100) | 100% (75.9 to 100) | 100% (77.1 to 100) | A:P supine, E hands on both sides, P exerts full abduction with both legs (paretic legs stays on midline) B:P exerts max strength on abducted leg (against E resistance) Sign—if paretic leg moves in adduction Sign+if paretic leg stays in position | Rather complex manoeuvre with no data on inter-rater reliability | Sonoo14 |
| Abductor finger sign | 100% (67.9 to 100) | 100% (65.5 to 100) | 100% (65.5 to 100) | 100% (67.8 to 100) | P abduction finger movement against resistance of E for 2 min with healthy hand. Synkinetic abduction finger movements of contralateral/‘paretic’ hand in functional paresis, no movement in ‘organic’ paresis | Can only be applied to patients with moderate paresis | Tinazzi et al15 |
| Spinal injury test | 98% (87.5 to 99.9) | 100% (73.2 to 100) | 93% (66.0 to 99.7) | 100% (90.6 to 100) | P supine position asked to lift up his knees, if not possible E lift them up Sign+if P keeps them up, sign—if leg drop in abduction | Can only be applied when a significant proximal leg weakness is present | Yugue et al18 |
| Collapsing/give-away weakness | 97% (89.4 to 99.1) | 63% (53.9 to 71.5) | 96% (88.7 to 99) | 65% (55.9 to 72.9) | Limb collapses from a normal position with a light touch or a normal strength is developed and then suddenly collapses (or gives-way) | Prone to error in patients with pain or who have difficulty following instructions | Stone et al21, Chabrol et al22, Gould et al8 |
| Co-contraction | 100% (82.2 to 100) | 17% (5.7 to 39.5) | 100% (39.6 to 100) | 55% (38.8 to 69.8) | Observation during muscle strength testing (or with surface electromyogram) Sign+if simultaneous contraction of agonist and antagonist resulting in no/little movement | Excessive antagonist activation can also be observed in spastic patients | Baker & Silver23, Knutsson 198523a |
| Motor inconsistency | 98% (85.3 to 99.9) | 13% (2.3 to 41.6) | 67% (12.5 to 98.2) | 75% (60.7 to 85.5) | Impossibility to do a movement while another movement using the same muscle is possible | Easy to detect but needs careful observation during the entire examination. Only formally evaluated in a single study | Chabrol et al22 |
| Not validated | |||||||
| Non-pyramidal weakness | Weakness is equally distributed in all muscle groups in functional cases Weakness is predominant in flexors>extensors and distal>proximal in pyramidal cases | Can only be used to differentiate with a central lesion and not a peripheral lesion | Freud3, Koehler 200423b | ||||
| Absent pronator drift | During the arm stabilisation test, hands in a supinated position: A downward drift and/or pronation is seen in organic but not in psychogenic paresis | Expert opinion Studies showing high specificity of this sign for organic paresis, but has never been tested in functional paresis | Babinski42 Teitelbaum et al35 , Anderson et al36 | ||||
| Arm drop test | E puts P's arm over the head (P lying supine) and drops the weak arm: In organic paresis the arm hits the face In functional paresis a voluntary movement allows avoiding the face | Only anecdotally reported Can only be applied in cases of complete paralysis of the arm | Reeves and Bullen40, Greer et al39, Marcus et al38 | ||||
| Barré test (‘manoeuvre de la jambe’) | P in prone position legs bent at 90°: In organic paresis, leg falls but contraction of hamstring muscle is seen In functional paresis, leg falls without contraction of the hamstrings OR no fall at all | Expert opinion | Barré41 | ||||
| Wrong way tongue deviation | In organic hemiparesis a slight tongue deviation towards the paresis can be seen. In functional paresis a strong deviation can occur, usually away from the paresis Sign+if tongue deviation away from the hemiparesis | Only one uncontrolled study | Keane49 | ||||
| Platysma sign (‘signe du peaucier’) | P is asked to open wide the mouth and/or to flex the chin towards the chest against E resistance In organic paresis a weakness is seen on the paretic side In functional paresis no asymmetry is seen | Expert opinion | Babinski42 | ||||
| Babinski trunk-thigh test | P supine position, arms across chest, asked to sit up In organic paresis, the paretic limb raises above the bed and the contralateral shoulder comes forward In functional paresis, no asymmetry is seen | Expert opinion | Babinski42 | ||||
| Supine catch sign | P is asked to put the hand in supination In organic paresis, the wrist joint stays in neutral position and fingers flex In functional paresis, the wrist hyper extends and fingers extend | Case report, only useful in cases of wrist drop (radial nerve palsy or hand knob cortical lesion) | Sethi et al44 | ||||
| Sternocleidomastoid test | Test the SCM strength by asking P to do a forced head rotation against E resistance. In organic hemiparesis SCM usually spared (as bilateral innervations). Sign+if weakness of rotation to the ipsilateral side | Controlled study but data only obtained on an abstract, article in Russian | Diukova45, Diukova and Stoliarova52 | ||||
| Sensory | |||||||
| Validated | |||||||
| Midline splitting | 93% (83.8 to 96.9) | 20% (6.6 to 44.2) | 40% (13.6 to 72,6) | 82% (72.4 to 89.2) | Sign+if exact splitting of sensation in the midline | The differential diagnosis includes small thalamic lesions | Rolak16, Stone et al21, Chabrol et al22, Gould et al8 |
| Splitting of vibration | 14% (7.3 to 23.7) | 95% (73.1 to 99.7) | 22% (13.8 to 31.9) | 92% (59.8 to 99.5) | Sign+if difference in the sensation of a tuning fork placed over the left compared to the right side of the sternum or frontal bone | A low specificity is reported from a single study. The assessment did not measure the degree of reported asymmetry | Rolak16 Gould et al8, Toth26 |
| Non anatomical sensory loss | 100% (82.2 to 100) | 74% (51.3 to 88.9) | 100% (77.1 to 100) | 79% (59.7 to 91.3) | Diminished sensation fitting a ‘non-dermatomal pattern’ for example: anteriorly but not posteriorly delineated truncal deficit, unilateral glove or sock distribution, sharp midline delineation in one limb (hemilimb distribution) | Evaluated in a single study with no precise description of what was considered ‘non-anatomical’ | Baker & Silver23 |
| Inconsistency/Changing pattern of sensory loss | 70% (56.8 to 80.4) | 79% (62.2 to 89.9) | 61% (46.2 to 74.5) | 85% (71.4 to 92.7) | Inconsistency and non reproducibility of sensory signs in repeated sensory testing | No precise description on how to perform the repeated tests | Baker & Silver23 Chabrol et al22 |
| Systematic failure | 100% (82.2 to 100) | 8.7% (1.5 to 29.5) | 100% (19.8 to 100) | 100% (36.9 to 67.3) | Sign+if patients always fails in a discriminative task (eg, pin or prick/cold-hot/upgoing or downgoing joint) | Evaluated in a single study but no precise description given on how many times the task should be repeated | Baker & Silver23 |
| Not validated | |||||||
| Bowlus-Currier test | P is asked to place palms together, thumbs down (wrist crossed), fingers interlocked and then rotate hands to bring them in front of the chest E performs sensory testing, starting on fifth finger up to the thumb (which is the only uncrossed finger) In functional paresis P reports that the healthy thumb is anaesthetic | Evaluated in a single study. Implies some ‘doctor trickery’ and should be used with caution | Bowlus and Currier48 | ||||
| Yes/no test | P, eyes closed, is asked to ‘yes’ when he feels E touching and ‘no’ when he does not | Implies some ‘doctor trickery’ and should be used with caution | Stone et al21, Magee25 | ||||
| Gait | |||||||
| Validated | |||||||
| Dragging monoplegic gait | 100% (90.4 to 100) | 8.4% (4.2 to 15.8) | 100% (62.9 to 100) | 32% (24.6 to 40.3) | The leg is dragged at the hip behind the body instead of performing a circumduction | Data available in a case-control study, as well as in two observational series | Stone et al21, Keane49, Ehrbar and Waespe 50 |
| Chair test | 100% (62.8 to 100) | 89% (50.7 to 99.4) | 100% (59.7 to 100) | 90% (54.1 to 99.4) | Sign+when P is seen to propel a swivel chair better than walking | Evaluated in a single study. Complex testing with no estimation of inter-rater reliability | Okun et al17 |
| Not validated | |||||||
| Fluctuation | Variability of gait with periods of normal gait are observed | Also possible in neurological disease (eg, myasthenia gravis) | Lempert et al51 Okun et al17 | ||||
| Excessive slowness | Excessive slowness or hesitation incompatible with a neurological disease is observed | Orthopaedics patients can walk slowly to avoid pain | Baik and Lang53, Lempert et al51, Okun et al17 | ||||
| Psychogenic Romberg | Constant falls towards or away from the observer, large amplitude body sway building up after a silent latency of a few seconds and improvement of balance with distraction | Evidence from a single study | Lempert et al51 | ||||
| Walking on ice | A walking pattern mimicking ice skating or ‘as if’ on slippery grounds | Evidence from a single study | Lempert et al51 | ||||
| Non-economic posture | A walking pattern that requires considerable effort as well as balance to maintain the posture (eg, walking with knees flexed) | Evidence from two studies, only providing descriptions | Lempert et al51, Okun et al17 | ||||
| Sudden knee buckling | Knee buckling during stance or walk but usually with no falls | Can be seen in chorea | Keane49, Baik and Lang53, Lempert et al51, Okun et al17 | ||||
| Staggering long to obtain support from opposite walls | Very instable gait but no falls, as subject will find a support, even if far out of reach | Evidence from a single study | Keane49 | ||||
| Exaggerated swaying without falling | Similar to the ‘psychogenic‘ Romberg above | Evidence from a single study | Keane49 | ||||
| Astasia-abasia | Complete inability to stand and walk despite normal leg function in bed | Thalamic lesions can cause an inability to stand (thalamic astasia) | Blocq29, Knapp49a, Baik 2007. Lempert et al51 | ||||
| Opposite of astasia-abasia | Complete inability to move legs in bed despite intact walking pattern | Reported in 23/47 patients in a single uncontrolled study | Ehrbar and Waespe 50 | ||||
| Sudden side steps | Functional patients will display big displacement in their trajectory with sudden side steps, without falling | Cerebellar ataxia (vermis) can also induce sudden side steps | Diukova Diukova and Stoliarova52 | ||||
| Cross legs | Patients will display a crossed legs or scissoring pattern of walk | Described in two studies | Diukova Diukova and Stoliarova52, Keane49 | ||||
| Expressive behaviour | ‘Suffering and strained facial expression’, mannered posture of the hand, moaning, hyperventilation | Patients with severe pain can display such behaviours | Lempert et al51 | ||||
E, examiner, P, patient; SCM, Sternocleidomastoid.