diagnostic lumbar puncture ( dlp ) is a frequent procedure used in the diagnosis of neural system disorders . post - lumbar puncture syndrome is a common complication of dlp occurring in about 340% of patients [ 14 ] . post - lumbar puncture headache ( plph ) is the predominant symptom of this syndrome , probably resulting from the leakage of cerebrospinal fluid into the epidural cavity through the post - puncture opening in the dura mater . the loss of cerebrospinal fluid causes a drop off in intracranial pressure ( icp ) , causing compensative dilatation of cerebral vessels , which is reflected by the headache [ 13 , 5 ] . this theory has one significant weakness , namely that plph do not occur in every patient following dlp . transcranial doppler ultrasonography ( tcd ) enables us to assess blood flow in the intracranial arteries non - invasively . assuming that tcd parameters are influenced both by changes in cerebral vessel diameters and by fluctuations in icp [ 68 ] , we aimed to verify if dlp resulted in significant changes in cerebral blood flow ( cbf ) that could be visualized by tcd . therefore , we identified a group of subjects who developed plph following dlp and compared their pre- and post - puncture blood flow parameters with respective values of plph - free subjects . this study included patients at the department of neurology , who required a scheduled dlp . exclusion criteria from this group included emergency lumbar punctures , inadequate temporal bone windows , stenosis of the middle cerebral arteries , hemodynamically significant stenosis of the common carotid arteries , atrial fibrillation , and patients who were immobilized . all the procedures were approved by the local ethics committee of the ludwik rydygier collegium medicum in bydgoszcz . tcd was performed 24  h before dlp and repeated within 24  h after the procedure . lumbar puncture was done following standard protocol by one of 11 physicians employed at the department . plph was diagnosed according to the international classification of headache disorders ( ich - ii ) guidelines . the presence and severity of plph was evaluated for 5  days , on a daily basis , using a numeric rating scale ( nrs ) . sixty - six patients were enrolled to this study , including 37 men and 29 women . the mean age of these patients was 47.4    16.5  years ( range from 16 to 88 , table  1 ) . patients were subjected to diagnostic procedures due to cranial mononeuropathy ( n  =  12 ) , polyneuropathy ( n  =  7 ) , multiple sclerosis ( n  =  13 ) , vertigo ( n  =  7 ) , diffuse injuries of the brain or spinal cord ( n  =  9 ) , epilepsy ( n  =  5 ) , and other reasons.table  1clinical characteristics of patients who developed post - lumbar puncture headache ( plph ) and in plph - free individualsparameterplph - free ( n  =  45)plph ( n  =  21)p valueage in years , mean    sd49.3    17.843.2    12.50.16women , n ( % ) 13 ( 28.9)16 ( 76.2)0.00031men , n ( % ) 32 ( 71.1)5 ( 23.8)0.00026history of headache , n ( % ) 9 ( 20)14 ( 66.7)0.00021  tension - type headache , n ( % ) 6 ( 13.3)11 ( 52)0.00034  migraine without aura , n ( % ) 3 ( 6.7)2 ( 9.5)0.21  other type of headache , n ( % ) 0 ( 0)1 ( 4.8)arterial hypertension , n ( % ) 12 ( 26.67)3 ( 14.29)0.26diabetes , n ( % ) 9 ( 20)2 ( 9.5)0.29hypercholesterolemia , n ( % ) 15 ( 33.3)4 ( 19.1)0.23hematocrit in % , mean    sd41.8 3.339.1    3.90.006hemoglobin in g / l , mean    sd14.2    1.313.0    1.50.001 clinical characteristics of patients who developed post - lumbar puncture headache ( plph ) and in plph - free individuals lumbar puncture was performed in the lateral recumbent position , using the intervertebral space between l4 and l5 or between l5 and s1 , with the aid of a 22-gauge needle ( bd spinal needle quincke type point ) . all the procedures were performed between 11 and 12 a.m. following the procedure , the patients were ordered to stay in bed for 8  h. tcd was performed using a pioneer apparatus ( nicolet / eme ) with a 2-mhz probe . following localization of the temporal window , the middle cerebral artery ( mca ) was identified . the probe was placed so as to record the peak possible velocity from the vessel . the measurements included mean velocity ( vmean ) , peak systolic velocity ( vmax ) , and gosling s pulsatility index ( pi ) at 5456  mm , in the left and right mca . all tcds were performed by the same physician being experienced in neurosonology and unaware of plph presence and severity in patients examined . mean values of normally distributed variables were compared with student s t test for independent samples , whereas the variables whose distributions were not normal were compared with the non - parametric mann distributions of discrete variables were compared between the groups with the aid of  test . calculations were performed using statistica 7 ( statsoft , poland ) software , and statistical significance was defined as p    0.05 . this study included patients at the department of neurology , who required a scheduled dlp . exclusion criteria from this group included emergency lumbar punctures , inadequate temporal bone windows , stenosis of the middle cerebral arteries , hemodynamically significant stenosis of the common carotid arteries , atrial fibrillation , and patients who were immobilized . all the procedures were approved by the local ethics committee of the ludwik rydygier collegium medicum in bydgoszcz . tcd was performed 24  h before dlp and repeated within 24  h after the procedure . lumbar puncture was done following standard protocol by one of 11 physicians employed at the department . plph was diagnosed according to the international classification of headache disorders ( ich - ii ) guidelines . the presence and severity of plph was evaluated for 5  days , on a daily basis , using a numeric rating scale ( nrs ) . sixty - six patients were enrolled to this study , including 37 men and 29 women . the mean age of these patients was 47.4    16.5  years ( range from 16 to 88 , table  1 ) . patients were subjected to diagnostic procedures due to cranial mononeuropathy ( n  =  12 ) , polyneuropathy ( n  =  7 ) , multiple sclerosis ( n  =  13 ) , vertigo ( n  =  7 ) , diffuse injuries of the brain or spinal cord ( n  =  9 ) , epilepsy ( n  =  5 ) , and other reasons.table  1clinical characteristics of patients who developed post - lumbar puncture headache ( plph ) and in plph - free individualsparameterplph - free ( n  =  45)plph ( n  =  21)p valueage in years , mean    sd49.3    17.843.2    12.50.16women , n ( % ) 13 ( 28.9)16 ( 76.2)0.00031men , n ( % ) 32 ( 71.1)5 ( 23.8)0.00026history of headache , n ( % ) 9 ( 20)14 ( 66.7)0.00021  tension - type headache , n ( % ) 6 ( 13.3)11 ( 52)0.00034  migraine without aura , n ( % ) 3 ( 6.7)2 ( 9.5)0.21  other type of headache , n ( % ) 0 ( 0)1 ( 4.8)arterial hypertension , n ( % ) 12 ( 26.67)3 ( 14.29)0.26diabetes , n ( % ) 9 ( 20)2 ( 9.5)0.29hypercholesterolemia , n ( % ) 15 ( 33.3)4 ( 19.1)0.23hematocrit in % , mean    sd41.8 3.339.1    3.90.006hemoglobin in g / l , mean    sd14.2    1.313.0    1.50.001 clinical characteristics of patients who developed post - lumbar puncture headache ( plph ) and in plph - free individuals lumbar puncture was performed in the lateral recumbent position , using the intervertebral space between l4 and l5 or between l5 and s1 , with the aid of a 22-gauge needle ( bd spinal needle quincke type point ) . the volumes of collected cerebral fluid ranged from around 610  ml . all the procedures were performed between 11 and 12 a.m. following the procedure , the patients were ordered to stay in bed for 8  h. tcd was performed using a pioneer apparatus ( nicolet / eme ) with a 2-mhz probe . following localization of the temporal window , the middle cerebral artery ( mca ) was identified . the probe was placed so as to record the peak possible velocity from the vessel . the measurements included mean velocity ( vmean ) , peak systolic velocity ( vmax ) , and gosling s pulsatility index ( pi ) at 5456  mm , in the left and right mca . all tcds were performed by the same physician being experienced in neurosonology and unaware of plph presence and severity in patients examined . mean values of normally distributed variables were compared with student s t test for independent samples , whereas the variables whose distributions were not normal were compared with the non - parametric mann distributions of discrete variables were compared between the groups with the aid of  test . calculations were performed using statistica 7 ( statsoft , poland ) software , and statistical significance was defined as p    0.05 . post - lumbar puncture headache was observed in 21 out of 66 patients who underwent dlp ( 32% ) , whereas symptoms of post - lumbar puncture syndrome were not noted in the remaining 45 subjects ( 68% ) . in most patients ( 86% ) , the symptoms manifested on the first day following dlp , on average 17.7    10.2  h after the procedure ( range 744  h ) . plph persisted 5.5    1.8  days on average ( range 210  days ) . female patients predominated amongst the plph cases ( 16 , compared to five men , p  <  0.0003 ) . most patients who developed plph ( n  =  14 ) had a history of headaches , mostly tension headaches . the mean age of patients with plph was lower than for unaffected individuals ( 43.2 vs. 49.3  years ) , but this difference was insignificant ( table  1 ) . in both groups of patients , no significant differences were observed in vmean , vmax and pi between the right and left mcas  both before dlp and following this procedure ( table  2).table  2pre- and post - puncture values ( mean    sd ) of mean velocity ( vmean ) , peak systolic velocity ( vmax ) , and gosling s pulsatility index ( pi ) in the right ( mca r ) and left ( mca l ) middle cerebral arteries of patients who developed post - lumbar puncture headache ( plph ) and in plph - free individualsplph - free ( n  =  45)plph ( n  =  21)p valuepre - puncture vmean , mca r ( m / s)55.2    9.771.9    24.90.0002post - puncture vmean , mca r ( m / s)55.5    12.658.4    20.20.47p value0.860.0004pre - puncture vmean , mca l ( m / s)55    12.0169.12    22.560.0015post - puncture vmean , mca l ( m / s)54.2    13.259.4    19.10.19p value0.700.008pre - puncture vmax , mca r ( m / s)89.9    16.2109.3    36.90.004post - puncture vmax , mca r ( m / s)91.1    21.589.8    30.10.84p value0.700.0002pre - puncture vmax , mca l ( m / s)89.8    19.4104.3    32.20.03post - puncture vmax , mca l ( m / s)88.7    20.490.7    28.00.74p value0.740.009pre - puncture pi , mca r0.99    0.200.86    0.140.01post - puncture pi , mca r1.0    0.210.89    0.120.03p value0.460.41pre - puncture pi , mca l0.98    0.220.84    0.130.01post - puncture pi , mca l0.99    0.230.86    0.130.01p value0.430.65 pre- and post - puncture values ( mean    sd ) of mean velocity ( vmean ) , peak systolic velocity ( vmax ) , and gosling s pulsatility index ( pi ) in the right ( mca r ) and left ( mca l ) middle cerebral arteries of patients who developed post - lumbar puncture headache ( plph ) and in plph - free individuals in patients who developed plph , bilateral pre - puncture values of vmean and vmax were significantly higher and pi was significantly lower compared to unaffected individuals . no significant differences were observed between these groups in terms of post - puncture vmean and vmax , but the post - puncture pi was still significantly lower in plph cases ( table  2 ) . moreover , hemoglobin concentration and hematocrit values were significantly lower in patients who developed headache compared to unaffected individuals ( table  1 ) . in plph cases , the post - puncture values of vmean and vmax were significantly lower than the respective baseline parameters . significant puncture - related changes in bilateral vmean and vmax were not observed in patients who did not develop plph . after the puncture , a slight increase in pi was observed bilaterally in both groups , but these changes lacked statistical significance ( table  2 ) . when study results were stratified according to patient gender , significant post - puncture changes in vmean and vmax were observed only in women ( p  <  0.01 and p  <  0.07 in right and left mca , respectively ) . a significant inverse correlation was present between plph severity on nrs and bilateral pre - puncture pi ( fig . 1).fig .  1correlation between post - lumbar puncture headache ( plph ) severity on numeric rating scale and pre - puncture gosling s pulsatility index ( pi ) in the left middle cerebral artery correlation between post - lumbar puncture headache ( plph ) severity on numeric rating scale and pre - puncture gosling s pulsatility index ( pi ) in the left middle cerebral artery post - lumbar puncture headache is believed to result from cerebrospinal fluid leakage through the post - puncture opening , with a subsequent decrease in intracranial pressure and cerebral vessel dilatation [ 13 , 5 ] . this theory was confirmed by our study . following the puncture , we observed significant decreases in vmean and vmax in bilateral mcas of patients who developed plph when compared to their respective pre - puncture values . the drop off in vmean and vmax observed in this group of patients may result from the dilatation of intracranial vessels , a consequence of lowered icp . similar puncture - related decreases in vmax in patients with plph were previously described by gobel et al . , but only affecting the right mca . in our study , significant puncture - related changes in vmean and vmax were not observed in bilateral mcas of plph - free individuals . presumably , the loss of cerebrospinal fluid in these patients was not significant enough to be reflected by compensative dilatation of cerebral vessels . the value of pi illustrates the resistance of a vascular bed ( supplied by a given artery ) when examined by tcd . there is a linear relationship between changes in pi and icp . a decrease in pi may result both from lowered icp and from vascular dilatation [ 7 , 8 ] . assuming that the loss of cerebrospinal fluid with further decrease in icp is the reason for plph , pi should decrease during the early phase of post - lumbar puncture syndrome . reactive dilatation of cerebral vessels due to decreased icp should result in further pi drop off . we did not observe significant puncture - related changes in pi , both in patients who developed plph and in unaffected individuals . presumably , icp fluctuations were slight or transient and therefore we failed to record them . noticeably , baseline ( pre - puncture ) pi values in patients who later developed plph were significantly lower compared to subjects free of this condition . this finding suggests that compensative dilatation of cerebral vessels does not accompany every decrease in icp but is rather characterized by low values of this parameter . there exist linear relationships between pi or vmax changes and changes in icp in cerebral vessels . pi is known to decrease and vmax to increase with lowered icp [ 7 , 8 ] . thus , it is likely that the baseline icp in patients who later developed plph was lower than in unaffected individuals . consequently , further icp drop off due to cerebrospinal fluid loss might result in compensative vascular dilatation in patients with plph . a relatively higher baseline icp in plph - free individuals might in turn protect them against intracranial  hypotension and resulting post - puncture headache . this theory was supported by a significant correlation observed in our study , between pre - puncture pi and plph severity : the lower the baseline pi ( and indirectly  icp ) the more severe the plph . in cases with plph , baseline vmean and vmax values were higher and pi lower than in unaffected individuals . vmean and vmax are known to decrease with age [ 6 , 11 ] . consequently , higher baseline values of these parameters in plph patients might be associated with the higher age of this group , compared to unaffected individuals . in our study , age differences between these two groups were insignificant , and therefore , unlikely to be responsible for the results found in this experiment . the predominance of women amongst the plph patients might be another potential reason for flow velocity differences observed between affected and unaffected individuals . higher vmean and vmax values were previously demonstrated in females compared to males and these differences were attributed to higher values of cbf in women [ 11 , 12 ] . additionally , our study revealed significantly lower hematocrit and hemoglobin values in plph subjects than in unaffected individuals . a lowered hematocrit is known to enhance flow velocity , and decreases pi due to reduced resistance . consequently , decreased hematocrit values might be responsible for higher values of vmean and vmax and lower pi observed in the plph cases . , hematocrit values do not influence flow velocities unless they are below 35% . in conclusion , the findings of this study partially confirm the theory behind the etiology of plph stated in the introduction , and suggest that higher baseline values of vmean and vmax and low pi in bilateral mcas predispose patients to this condition . additional risk factors of plph were observed to include female gender , history of headaches , and decreased hematocrit and hemoglobin levels . finally , within the 24  h following puncture , significant decreases in vmean and vmax were observed in bilateral mcas of patients who developed plph .
the aim of this study was to verify if diagnostic lumbar puncture ( dlp ) in post - lumbar puncture headache ( plph ) patients is related to significant changes in cerebral blood flow which could be visualized by transcranial doppler ( tcd ) . 
 sixty - six patients were enrolled in this study . 
 tcd was performed 24  h before dlp and repeated within 24  h after the procedure . 
 the measurements included mean velocity ( vmean ) , peak systolic velocity ( vmax ) , and gosling s pulsatility index ( pi ) , in the left and right middle cerebral artery ( mca ) . 
 plph was observed in 21 patients ( 32% ) . 
 no significant differences were noted in vmean , vmax and pi between the right and left mcas  both before dlp and following this procedure . in patients who developed plph , bilateral pre - puncture values of vmean and vmax 
 were significantly higher and pi was significantly lower compared to unaffected individuals . 
 no significant differences were observed between these groups in terms of post - puncture vmean and vmax , but the post - puncture pi was still significantly lower in plph cases . in plph cases , 
 the post - puncture values of vmean and vmax were significantly lower than the respective baseline parameters . 
 a significant inverse correlation was present between plph severity and bilateral pre - puncture pi . in conclusion 
 , this study revealed that higher baseline values of vmean and vmax and low pi in bilateral mcas predispose patients to plph .