Table 1

Positive signs of functional motor, sensory and gait disorders

Clinical signEstimated specificity (CI)Estimated sensitivity (CI)Positive predictive value (CI)Negative predictive value (CI)DescriptionCommentReferences
Motor
Validated
 Hoover sign99% (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 painStone et al21, Sonoo 14,
Tinazzi et al15, McWhirter et al13, Ziv et al19
 Abductor sign100% (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 reliabilitySonoo14
 Abductor finger sign100% (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’ paresisCan only be applied to patients with moderate paresisTinazzi  et al15
 Spinal injury test98% (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 presentYugue et al18
 Collapsing/give-away weakness97% (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 instructionsStone et al21, Chabrol et al22, Gould et al8
 Co-contraction100% (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 patientsBaker & Silver23, Knutsson 198523a
 Motor inconsistency98% (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 possibleEasy to detect but needs careful observation during the entire examination. Only formally evaluated in a single studyChabrol  et al22
Not validated
 Non-pyramidal weaknessWeakness 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 lesionFreud3, Koehler 200423b
 Absent pronator driftDuring 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 testE 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 opinionBarré41
 Wrong way tongue deviationIn 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 studyKeane49
 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 opinionBabinski42
 Babinski trunk-thigh testP 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 opinionBabinski42
 Supine catch signP 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 testTest 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 sideControlled study but data only obtained on an abstract, article in RussianDiukova45, Diukova and Stoliarova52
Sensory
Validated
 Midline splitting93% (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 midlineThe differential diagnosis includes small thalamic lesionsRolak16, Stone  et al21,
Chabrol  et al22, Gould et al8
 Splitting of vibration14% (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 boneA low specificity is reported from a single study. The assessment did not measure the degree of reported asymmetryRolak16
Gould et al8, Toth26
 Non anatomical sensory loss100% (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 loss70% (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 testingNo precise description on how to perform the repeated testsBaker  & Silver23 Chabrol  et al22
 Systematic failure100% (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 repeatedBaker  & Silver23
Not validated
 Bowlus-Currier testP 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 cautionBowlus and Currier48
 Yes/no testP, eyes closed, is asked to ‘yes’ when he feels E touching and ‘no’ when he does notImplies some ‘doctor trickery’ and should be used with cautionStone  et al21,
Magee25
Gait
Validated
 Dragging monoplegic gait100% (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 circumductionData available in a case-control study, as well as in two observational seriesStone  et al21, Keane49, Ehrbar and Waespe 50
 Chair test100% (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 walkingEvaluated in a single study. Complex testing with no estimation of inter-rater reliabilityOkun et al17
Not validated
 FluctuationVariability of gait with periods of normal gait are observedAlso possible in neurological disease (eg, myasthenia gravis)Lempert et al51
Okun et al17
 Excessive slownessExcessive slowness or hesitation incompatible with a neurological disease is observedOrthopaedics patients can walk slowly to avoid painBaik and Lang53, Lempert et al51, Okun et al17
 Psychogenic RombergConstant 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 distractionEvidence from a single studyLempert et al51
 Walking on iceA walking pattern mimicking ice skating or ‘as if’ on slippery groundsEvidence from a single studyLempert et al51
 Non-economic postureA 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 descriptionsLempert et al51, Okun et al17
 Sudden knee bucklingKnee buckling during stance or walk but usually with no fallsCan be seen in choreaKeane49, Baik  and Lang53, Lempert et al51, Okun et al17
 Staggering long to obtain support from opposite wallsVery instable gait but no falls, as subject will find a support, even if far out of reachEvidence from a single studyKeane49
 Exaggerated swaying without fallingSimilar to the ‘psychogenic‘ Romberg aboveEvidence from a single studyKeane49
 Astasia-abasiaComplete inability to stand and walk despite normal leg function in bedThalamic lesions can cause an inability to stand (thalamic astasia)Blocq29, Knapp49a, Baik 2007. Lempert et al51
 Opposite of astasia-abasiaComplete inability to move legs in bed despite intact walking patternReported in 23/47 patients in a single uncontrolled studyEhrbar and Waespe 50
 Sudden side stepsFunctional patients will display big displacement in their trajectory with sudden side steps, without fallingCerebellar ataxia (vermis) can also induce sudden side stepsDiukova Diukova and Stoliarova52
 Cross legsPatients will display a crossed legs or scissoring pattern of walkDescribed in two studiesDiukova Diukova and Stoliarova52, Keane49
 Expressive behaviour‘Suffering and strained facial expression’, mannered posture of the hand, moaning, hyperventilationPatients with severe pain can display such behavioursLempert et al51
  • E,  examiner, P, patient; SCM, Sternocleidomastoid.