surgical intervention in epilepsy is a widely accepted , effective therapy in patients with pharmacoresistant partial epilepsy .
seizure semiology correlates with the seizure origin , spread , and release phenomenon and can help in the estimation of the anatomical brain localization .
finger snapping has been noted as a common act for centuries and is employed in securing someone else 's attention .
the sound of the snap is created by forcing air out between the fingers with an audible crack .
automatisms involving the distal segments of the upper or lower limbs are frequent during seizures   and , when unilateral , often indicate ipsilateral seizure onset , mostly in the temporal lobe or in the orbitofrontal region , .
finger snapping could be interpreted as a temporal lobe automatism , but the fierceness of the finger - snapping movement associated with tonic abduction of the upper limb could indicate a focus in the supplementary motor area ( sma ) , .
we describe two patients in whom invasive intracranial eeg evaluation was performed to localize the seizure onset for surgical intervention . both patients showed ictal snapping of the right hand fingers , which has not previously been described in literature .
a 34-year - old right - handed man was seen at the montreal neurological hospital for investigation of refractory seizures .
his seizures began at the age of seven , two years after a right - sided head trauma .
early eegs revealed an active epileptiform anomaly over the right midfrontal region . over the years , he showed fluctuation in frequency and severity of seizures , which eventually remained refractory .
1.5-tesla mri showed no structural abnormalities . during admission for video - eeg , typical clinical seizures occurred predominantly during sleep , without aura , and were defined as tonic posturing with fencing , extension of the right arm , snapping of the right hand fingers , and some pedaling movement .
electroencephalography telemetry showed several seizures not only with bilateral background activity changes , such as generalized epileptiform anomalies , but also with focal attenuation over the right frontal or temporal regions . for nine days , intracranial stereo - eeg exploration with 11-contact depth electrodes was performed , exploring both frontal lobes and the right temporal lobe ( fig .  1 ) .
active interictal epileptiform discharges were seen in the right hippocampal formation , and an independent , less active interictal epileptiform anomaly was found in the mesial aspect of the right orbitofrontal lobe .
twenty - five seizures were recorded , mostly nocturnal , with a semiology typical for this patient 's seizure pattern : they were usually brief , lasting 22 to 40  s , consisting of tonic posturing with fencing , extension of the right arm and elevation and flexion of the left arm , deviation of the head to the right , and discreet pedaling with both legs .
right hand finger snapping was observed in 10/25 ( 40% ) seizures during the second half of the ictal phase .
electrographical onsets were bilateral and frontal with often right - sided predominance and maximum involvement of the sma .
the finger snapping coincided with the discharge spreading to the right temporal lobe to both mesial hippocampal and more superficial temporal channels .
a typical seizure was electrically evoked when the right mesial orbitofrontal area was stimulated ( biphasic square wave stimulus , 60  hz , 4  ma , 3  s ) , with finger snapping occurring 12  s after onset and while a rhythmic discharge was seen in the right temporal lobe ( supplementary video  1 ) .
the patient first underwent a restricted resection of the right anterior orbitofrontal region and , one year later , a more extensive anterior frontal resection with no changes in seizure frequency or in semiology .
a 15-year - old right - handed girl was seen at the university medical center utrecht for investigation of pharmacoresistant seizures .
magnetic resonance imaging showed a left mesial parietal focal cortical dysplasia . during admission for video - eeg , typical clinical seizures consisted of gazing and grunting , twitching of the upper body , head , right arm , and
ictal eeg showed irregular slow wave activity over the left laterofrontal and frontotemporal regions and diffuse spread in the left hemisphere .
intracranial subdural grids were placed over the mesial aspect of both the frontoparietal region and the convexity of the left centroparietotemporal neocortex ( fig .  1 ) .
active interictal multifocal epileptiform discharges occurred near the mesial parietal lesion , more laterally over the parietotemporal transition area and the inferotemporal surface .
twenty - two typical seizures were recorded , and 3/22 ( 13% ) were with typical finger snapping which started few seconds after seizure onset .
these three attacks consisted of gazing and grunting , twitching of the head , and a right hand finger snapping .
ictal corticography showed gamma activity over the mesial aspect of the parietal lobe and caudal to the lesion prior to clinical symptoms .
the discharge then spread to the parietotemporal transition area and the inferotemporal surface ( supplementary video  1 ) .
this patient eventually underwent resection , and the lesion turned out to be focal cortical dysplasia ( 2b ) .
resection was restrained by eloquent functions of the brain tissue , postoperative mri showed rests of the cortical dysplasia , and postsurgical seizures remained unchanged .
a 34-year - old right - handed man was seen at the montreal neurological hospital for investigation of refractory seizures .
his seizures began at the age of seven , two years after a right - sided head trauma .
early eegs revealed an active epileptiform anomaly over the right midfrontal region . over the years , he showed fluctuation in frequency and severity of seizures , which eventually remained refractory .
1.5-tesla mri showed no structural abnormalities . during admission for video - eeg , typical clinical seizures occurred predominantly during sleep , without aura , and were defined as tonic posturing with fencing , extension of the right arm , snapping of the right hand fingers , and some pedaling movement .
electroencephalography telemetry showed several seizures not only with bilateral background activity changes , such as generalized epileptiform anomalies , but also with focal attenuation over the right frontal or temporal regions . for nine days , intracranial stereo - eeg exploration with 11-contact depth electrodes was performed , exploring both frontal lobes and the right temporal lobe ( fig .  1 ) .
active interictal epileptiform discharges were seen in the right hippocampal formation , and an independent , less active interictal epileptiform anomaly was found in the mesial aspect of the right orbitofrontal lobe .
twenty - five seizures were recorded , mostly nocturnal , with a semiology typical for this patient 's seizure pattern : they were usually brief , lasting 22 to 40  s , consisting of tonic posturing with fencing , extension of the right arm and elevation and flexion of the left arm , deviation of the head to the right , and discreet pedaling with both legs .
right hand finger snapping was observed in 10/25 ( 40% ) seizures during the second half of the ictal phase .
electrographical onsets were bilateral and frontal with often right - sided predominance and maximum involvement of the sma .
the finger snapping coincided with the discharge spreading to the right temporal lobe to both mesial hippocampal and more superficial temporal channels .
a typical seizure was electrically evoked when the right mesial orbitofrontal area was stimulated ( biphasic square wave stimulus , 60  hz , 4  ma , 3  s ) , with finger snapping occurring 12  s after onset and while a rhythmic discharge was seen in the right temporal lobe ( supplementary video  1 ) .
the patient first underwent a restricted resection of the right anterior orbitofrontal region and , one year later , a more extensive anterior frontal resection with no changes in seizure frequency or in semiology .
a 15-year - old right - handed girl was seen at the university medical center utrecht for investigation of pharmacoresistant seizures .
magnetic resonance imaging showed a left mesial parietal focal cortical dysplasia . during admission for video - eeg , typical clinical seizures consisted of gazing and grunting , twitching of the upper body , head , right arm , and
ictal eeg showed irregular slow wave activity over the left laterofrontal and frontotemporal regions and diffuse spread in the left hemisphere .
intracranial subdural grids were placed over the mesial aspect of both the frontoparietal region and the convexity of the left centroparietotemporal neocortex ( fig .  1 ) .
active interictal multifocal epileptiform discharges occurred near the mesial parietal lesion , more laterally over the parietotemporal transition area and the inferotemporal surface .
twenty - two typical seizures were recorded , and 3/22 ( 13% ) were with typical finger snapping which started few seconds after seizure onset .
these three attacks consisted of gazing and grunting , twitching of the head , and a right hand finger snapping .
ictal corticography showed gamma activity over the mesial aspect of the parietal lobe and caudal to the lesion prior to clinical symptoms .
the discharge then spread to the parietotemporal transition area and the inferotemporal surface ( supplementary video  1 ) .
this patient eventually underwent resection , and the lesion turned out to be focal cortical dysplasia ( 2b ) .
resection was restrained by eloquent functions of the brain tissue , postoperative mri showed rests of the cortical dysplasia , and postsurgical seizures remained unchanged .
, patients extended the right arm and snapped the right hand fingers . in one patient
when this patient was requested to snap his fingers on purpose , he could not snap as loudly . in both patients ,
the sma was involved early in the seizure , with spread to the orbitofrontal and parietal areas .
the eeg activity at the start of the finger snapping during these seizures coincided with the spread of discharge into the temporal lobe , which suggests that finger snapping represents another upper limb automatism generated or modulated by the temporal lobe .
the localizing precision is , however , limited as snapping occurred only during seizure spread .
in the first patient , the predominant activity was ipsilateral to the finger snapping , but the contralateral temporal lobe was not implanted .
the temporal seizure activity seemed contralateral , but , in this case , the ipsilateral side was not explored .
however , video - eeg showed only contralateral activity . within the temporal lobe , the spread of activity seemed to differ between patients which could result from different recording methods , depth versus corticography .
the sampling of the implantations imposes a limitation to our hypothesis . in both patients , epilepsy surgery of the mesiofrontal and parietal cortex
the semiology was unchanged , which fits with our hypothesis of the involvement of the sma and temporal lobes .
investigation of ictal behavior through video - eeg monitoring has led to the recognition of a number of typical clinical signs , including oral and limb automatisms such as lip smacking , swallowing , chewing , and exploratory movements in temporal lobe epilepsy , .
finger snapping has not been described as a typical ictal sign or following electrocortical stimulation .
it might be a type of rhythmic ictal nonclonic hand motions which are associated with contralateral temporal lobe seizures .
a number of studies specifically compared semiologic features of frontal lobe seizures with those of temporal lobe seizures , , , .
leg movements such as pedaling and kicking , tonic posturing , and tonic  clonic movements seem to occur more frequently in frontal lobe seizures , while oral , exploratory , and hand automatisms are seen more frequently in temporal lobe seizures , .
automatisms have been quantitatively analyzed by yang et al . , and they suggest limb movements during temporal lobe epilepsy to be predominantly distal , while , in frontal lobe epilepsy , proximal movements are predominant .
ictal finger snapping might be interpreted as a combination of two common features of epileptic seizures .
the start of snapping in fact follows a tonic abduction of the distal part of the right arm with high muscle tension in the fingers , which is seen in supplementary motor seizures , .
the subsequent repetitive snapping of fingers can be interpreted as an automatism of the right hand , originating from the involvement of the temporal lobe , .
this is supported by the evolution of the movement in patient 2 in whom the finger - snapping movement seems to start as a slow rhythmic pill - rolling movement , gets stronger , and eventually becomes finger snapping .
this could emphasize that finger snapping could be atypical unilateral motor automatisms but , in a way , similar to classical temporal automatisms .
in two cases of ictal finger snapping , the ictal onset zone was near the supplementary motor area , with spread to the temporal lobe .
we hypothesize that this semiology is a combination of muscle tension of the hand from supplementary motor area activation followed by an automatism of snapping originating from temporal lobe involvement .
the following are the supplementary data related to this article.supplementary video  1supplementary video sequences patient 1.seizure 1 in this seizure , rhythmic activity is seen bilaterally in the sma , spreading into the orbitofrontal area . during the finger - snapping movements ,
the seizure consists of sudden arousal with deviation of the head to the right followed by tonic posture of the right arm and snapping of the right hand fingers .
the patient rolls onto his right side and moves to a sitting position.seizure 2 in this seizure , the onset is bilateral with a low - voltage fast discharge seen diffusely in the right frontal lobe structures .
this is followed by a rhythmic polyspike discharge seen exclusively in the right temporal lobe .
postictally , there is a marked attenuation and slowing of background activity predominating in the right and in the frontal lobe .
clinically , it consists of a sudden arousal without aura associated with breathing change . there is tonic posturing of the arms and body , tonic deviation of the head to the right , and snapping of the right hand fingers.supplementary video sequences patient 2.seizure 1 in this seizure , gamma activity is seen in the posterior interhemispheric area .
spike  wave complexes arise in the parietal grid , and , during the finger - snapping movements , there is an increase in spike  wave complexes over the inferotemporal area .
clinically , the seizure starts with grimacing , a sudden deviation of the head to the left , and pulling off the blankets .
the patient , now looking at her right hand , moves her right arm up and starts snapping the right hand fingers.seizure 2 in this seizure , gamma activity is first seen in the anterior interhemispheric area , spreading towards the posterior interhemispheric electrodes mixed with synchronous spike  waves at 1  hz in the parietal , temporal , and later frontal grids . during the finger - snapping movements ,
there is a transition into 8-hz spike  wave activity in the anterior interhemispheric and parietal grids .
clinically , the seizure starts with deviation of the head to the left and movement to an upward position with the upper body .
the patient moves her right arm to the backside and starts snapping the right hand fingers , while her head still deviates to the left.supplementary material.supplementary figure  2 , eeg patient 1depth eeg of patient 1 at time of seizure onset .
lo : left orbitofrontal electrodes , lc : left cingulate , ls : left sma , ra : right amygdala , rh : right hippocampus , ro : right orbitofrontal , rs : right sma .
the uppermost channel of the group of channels from one electrode is the deepest contact of that electrode.supplementary figure  3 , eeg patient 2intracranial subdural eeg of patient 2 at time of seizure onset .
iha : interhemispheric strip anterior ( 1    8) , ihp : interhemispheric strip posterior ( 1    8) .
the parietal grid is an 8    8 grid , and the temporal grid is a 2    8 grid .
the uppermost channel of the group of channels of a strip electrode is the contact furthest away from the craniotomy of that electrode .
the parietal grid shows the channels in order from left to right and then from top to bottom .
, rhythmic activity is seen bilaterally in the sma , spreading into the orbitofrontal area . during the finger - snapping movements ,
the seizure consists of sudden arousal with deviation of the head to the right followed by tonic posture of the right arm and snapping of the right hand fingers .
the patient rolls onto his right side and moves to a sitting position . in this seizure ,
the onset is bilateral with a low - voltage fast discharge seen diffusely in the right frontal lobe structures .
this is followed by a rhythmic polyspike discharge seen exclusively in the right temporal lobe .
postictally , there is a marked attenuation and slowing of background activity predominating in the right and in the frontal lobe .
there is tonic posturing of the arms and body , tonic deviation of the head to the right , and snapping of the right hand fingers .
spike  wave complexes arise in the parietal grid , and , during the finger - snapping movements , there is an increase in spike  wave complexes over the inferotemporal area .
clinically , the seizure starts with grimacing , a sudden deviation of the head to the left , and pulling off the blankets .
the patient , now looking at her right hand , moves her right arm up and starts snapping the right hand fingers . in this seizure
, gamma activity is first seen in the anterior interhemispheric area , spreading towards the posterior interhemispheric electrodes mixed with synchronous spike  waves at 1  hz in the parietal , temporal , and later frontal grids . during the finger - snapping movements ,
there is a transition into 8-hz spike  wave activity in the anterior interhemispheric and parietal grids .
clinically , the seizure starts with deviation of the head to the left and movement to an upward position with the upper body .
the patient moves her right arm to the backside and starts snapping the right hand fingers , while her head still deviates to the left .
lo : left orbitofrontal electrodes , lc : left cingulate , ls : left sma , ra : right amygdala , rh : right hippocampus , ro : right orbitofrontal , rs : right sma .
the uppermost channel of the group of channels from one electrode is the deepest contact of that electrode .
iha : interhemispheric strip anterior ( 1    8) , ihp : interhemispheric strip posterior ( 1    8) .
f : frontal ( 2    4 ) . the parietal grid is an 8    8 grid , and the temporal grid is a 2    8 grid .
the uppermost channel of the group of channels of a strip electrode is the contact furthest away from the craniotomy of that electrode .
the parietal grid shows the channels in order from left to right and then from top to bottom .
 we describe two patients who showed snapping of the right hand fingers during invasive intracranial eeg evaluation for epilepsy surgery . 
 we correlated the eeg changes with the finger - snapping movements in both patients to determine the underlying pathophysiology of this phenomenon . at the time of finger snapping , eeg spread from the supplementary motor area towards the temporal region 
 was seen , suggesting involvement of these sites . 
Introduction
Case reports
Patient 1
Patient 2
Discussion
Conclusion