Incidence Of Postdural Puncture Headache Research Articles

Comparison of incidence of PDPH between two different gauges of whitacre spinal needles in patients undergoing caesarean section

Background: One of the complications of spinal anesthesia especially in pregnant women is post dural puncture headache (PDPH). Objectives of the study was to compare the incidence of PDPH between 25G and 27G Whitacre spinal needles and to compare the ease of lumbar puncture. Materials and Methods: Two hundred elective caesarean section patients were allocated into two groups of 100 each. In Group 1, Spinal anesthesia was given with 25 G and in group 2 with 27 G Whitacre needle. Results: Incidence of PDPH between two groups is not statistically significant with zero percent incidence. It was technically easier to perform lumbar puncture with 25 G Whitacre needle than 27 G needle which was statistically significant. Conclusion: It is technically easier to perform lumber puncture with 25G whitacre needle with no difference in the incidence of PDPH between 25G and 27G Whitacre needle.

The Relationship between the Phases of the Menstrual Cycle on the Incidence and Severity of Headache after Spinal Anesthesia.

Introduction Headache after spinal anesthesia is a common complication, which is caused after dural puncture due to discharge of cerebrospinal fluid and reduction in the volume and pressure. Studies have shown that a variety of factors are involved including needle shape, needle size, patient's sex, age, duration of surgery, history of spinal anesthesia, and history of headaches. One possible factor is the phase of the menstrual cycle. Many studies have investigated the effect of the menstrual cycle on factors such as postoperative nausea, vomiting, propofol injection pain, and sore throat after intubation. Also, many studies have investigated the effect of different phases of the menstrual cycle on migraine headaches. Therefore, we decided to investigate the effect of different phases of the menstrual cycle on headache after spinal anesthesia. Materials and Methods To determine the relationship between headache after spinal anesthesia and menstrual cycle, the study included all the patients undergoing spinal anesthesia in Shohada Ashayer and Asalian Hospitals of Khorramabad. This cohort study included 279 patients, and data collection tool was a questionnaire. The data from the questionnaire included age, menstrual phase, surgical procedures, pain location, pain intensity, history of spinal anesthesia, history of headache, and headache after spinal anesthesia. Results There was no statistically significant difference between the location of headache, the history of spinal anesthesia, the location of headache, the history of headache, and menstrual phase. Conclusion Considering the high incidence of postdural puncture headache in follicular phase, it is recommended that patients with a high risk of headaches undergo spinal anesthesia and surgery in the luteal phase.

POST-DURAL PUNCTURE HEADACHE AND RISK FACTORS IN WOMEN UNDERGOING CESAREAN SECTION WITH SPINAL ANESTHESIA

Objective: To estimate the incidence of post-dural puncture headache (PDPH) and risk factors in women underwent Cesarean section with spinal anesthesia. Materials and method: In a prospective descriptive study, parturients underwent Cesarean section with spinal anesthesia. Incidence of post-dural puncture headache, the history of spinal anesthesia and PDPH, presence of headache, preeclampsia, migraine, sinusitis, caffeine withdraw, insertion site, repeated puncture attempts, direction of the needle, size of the needle, local anesthesic, perioperative hypotension, nausea and vomiting, amount of intravenous fluid were recorded. Results: There were 389 patients in the study. The incidence of PDPH was 14.65% (mild and moderate pain: 75.44%; severe pain 21.05%; worst pain: 3.51%). The risk factors were history of PDPH (OR = 4.5; 95% CI: 1.8 - 11.09), sinusitis (OR = 2.65; 95% CI: 1.10 - 6.36), local anesthesia (Marcain spinal 0.5% heavy) (OR = 6.66; 95% CI: 2.25 - 19.11), perioperative hypotension (OR = 2.42; 95% CI: 1.25 - 4.70). Conclusion: The incident of PDPH in women undergoing Cesarean section with spinal anesthesia was 14.65%. Four risk factors were the history of PDPH, sinusitis, local anesthesia (Marcain spinal 0.5% heavy) and perioperative hypotension. Key words: post-dural puncture headache (PDPH), Cesarean section, spinal anesthesia

Effect of Coffee Consumption on the Incidence of Post Dural Puncture Headache among Patients Receiving Spinal Anesthesia

Spinal anesthesia provides excellent outcome for surgeries below the umbilicus like varicose veins surgery. Unfortunately, spinal anesthesia has complications such as Post Dural Puncture Headache (PDPH). Conservative treatments of PDPH include vasoconstrictors such as caffeine that found in coffee. The nurse observes patients for post spinal anesthesia complications especially Post Dural Puncture Headache (PDPH) and gives appropriate nursing interventions. Design: Quasi-experimental research design was used in this study. Aim: to determine effect of coffee consumption on the incidence of Post Dural Puncture Headache among patients receiving spinal anesthesia. Hypothesis of the study: Postoperative patients who consume coffee exhibit less incidence of Post Dural Puncture Headache than who don’t consume it. Setting: The study was carried out in Main University Hospital, Alexandria. Egypt. Subjects: The sample of the study consisted of a convenience sample of 60 postoperative patients (had varicose veins surgery) received spinal anesthesia. They were divided randomly into 2 equal groups, control and study (coffee) groups. Tool: Postoperative Headache Assessment Sheet was used in order to collect data. It included four parts: Part I: Bio-socio demographic data, Part II: Headache diagnosis, Part III: Headache assessment items, and Part IV: Assessment of needing for analgesics. Results: The chief result in this study was that the incidence of PDPH is less in coffee group than in the control group with statistical significant differences between both groups (P= (0.001*, 0.020*, 0.020*, 0.038*) after 4 hours, first, second, and third days, respectively. Conclusion: The study hypothesis was accepted as incidence of Post Dural Puncture Headache is decreased in postoperative patients who consumed coffee than in those who don’t consume it. Recommendation: Replicate this study among different samples (age, sex, diagnosis, type of operation).

The effect of intravenous administration of ondansetron compared toaminophylline on incidence and severity of post-dural puncture headache(PDPH) in cesarean section surgeries

Background: Post-dural puncture headache is a common complication of spinal anesthesia mostly in parturient. The aim of this study is to evaluate and compare the effect of ondansetron and aminophylline on PDPH. Methods: In this study we administered (1 mg/kg) of aminophylline in group A, (0.15 mg/kg) of ondansetron in group B and 5 cc of normal saline as placebo in control group. Blood pressure and heart rates were monitored since entrance of the patient to the operating room till the end of stay in recovery room and any significant changes were documented. Afterwards, PDPH and post-operative nausea and vomiting were followed during 24, 48 and 72 h periods since the performance of spinal anesthesia by calling each patient and the severity of headache was noted by numerical rating scale which had been already explained to the patients. Results: Although there was no difference in the incidence of PDPH among three group cases (p=0.89), the severity of the headache was significantly lower in the ondansetron group (NRS: 4.82) comparing to aminophylline (NRS: 7.71) and control (NRS: 6.65) groups (P<0.001). Moreover, the data showed that significant hypotension occurring during operating time, results in twice as much PDPH afterwards (p=0.009). Conclusion: This study shows that although (0.15 mg/kg) ondansetron does not reduce the incidence of PDPH, it significantly reduces the severity of headache also shows that aminophylline has no effect on reduction of incidence nor severity of PDPH.

Effect of intrathecal catheterisation on incidence of postdural puncture headache after accidental dural puncture in non-obstetric patients.

Background and Aims:After accidental dural puncture (ADP) with large bore epidural needles, postdural puncture headache (PDPH) develops in 16%–86% of patients, which is unpleasant and interferes with activities of daily life of the patient. Hence we aimed to assess the effect of intrathecal catheter insertion after ADP with 18G Tuohy needle on incidence of PDPH.Material and Methods:In all, 173 patients after ADP were enrolled and divided into two groups according to the choice of treating anesthesiologist. Group IC included 74 patients who had intrathecal catheter placed in subarachnoid space. In group NIC, which included 99 patients, one of the following was done: epidural catheter was cited in a different intervertebral space, or the procedure was abandoned and general anesthesia was administered or single-shot spinal anesthesia was administered through the Tuohy needle itself. The catheters were left in situ for 36–48 h. Patients were monitored for the next 7 days after ADP for the incidence of PDPH, its severity and requirement of analgesics, and duration of catheter in situ from the time of ADP.Results:The incidence of PDPH in group IC was 36% in comparison to 59% in group NIC (P = 0.001). The severity of PDPH and requirement of analgesics was significantly less in group IC.Conclusion:Insertion of intrathecal catheter at the site of ADP significantly reduces the incidence and severity of PDPH.

A randomized study to evaluate post-dural puncture headache after cesarean section: Comparison with median and paramedian approaches.

Although the most popular anesthesia technique for cesarean is spinal anesthesia, its most common complication is post-dural puncture headache (PDPH). We aimed to determine the effect of median and paramedian approaches during spinal anesthesia on PDPH in patients undergoing cesarean section. 200 pregnant women between the ages of 19-45 years, ASA physical status II, scheduled to undergo elective cesarean section under spinal anesthesia, were studied. The patients were randomized into two groups: Group M; (n = 100) spinal anesthesia with the median approach, Group PM; (n = 100) spinal anesthesia with paramedian approach. The patients were questioned for the possible occurrence of PDPH on the first, third and seventh postoperative days. A telephone follow-up call was used if the hospital stay was shorter than seven days. Post-dural puncture headache was evaluated according to the International Classification of Headache Disorders (ICHD-III) diagnostic criteria. Normally distributed data were summarized using mean and standard deviation. Skewed data were summarized using median (range). A total of 200 patients completed the study. There were no statistically different between the groups by comparing the incidence and characteristics of PDPH (32% vs. 28%, P = 0.548). Most patients rated their pain intensity during PDPH as mild to moderate in both groups (p = 0.721). PDPH onset time was 2 (1-4) days in Group PM versus 3 (1-7) days in Group M (p = 0.173). No patient needed for epidural blood patch in both groups. Spinal anesthesia with a median or paramedian approach at cesarean section has no effect on the incidence of PDPH, but we believe that there has been a need for further studies with larger or different patient populations.

Impact of spinal needle design and approach to postdural puncture headache and spinal anesthesia failure in obstetrics

Concern has been raised that Sprotte needles predispose to spinal anes-thesia failure. Nevertheless, these needles are associated with alow incidence of postdural puncture headache. The impact of the paramedian approach to postdural puncture headache remains controversial. The objective of this prospective randomized study was to compare Sprotte, Quincke and Atraucan needles as well as the midline and the paramedian approach in terms of postdural puncture headache and spinal anesthesia failure in patients undergoing Caesarean section. 655 patients were randomized to 5 groups. Amidline approach was used in four groups. The spinal needles were the 25G Sprotte, 27G Sprotte, 26G Atraucan and 25G Quincke. In the fifth group a25G Quincke needle was used by the paramedian approach. The incidence of postdural puncture headache was 0% in both 25G and 27G Sprotte groups, 2.5% in the 26G Atraucan group, and 7.2% and 2.7% in the 25G Quincke midline and paramedian approach respectively. Asignificant difference in terms of postdural puncture headache was found between 25G Sprotte and 25G Quincke needles (P = 0.004), while the failure rate was similar between these two needles. Asignificant difference in spinal anesthesia failure rate was observed between midline and paramedian approaches (P = 0.041). Sprotte but not Atraucan needle design correlates with lower incidence of postdural puncture headache compared to Quincke design. Sprotte needles are not associated with ahigher spinal anesthesia failure compared to Quincke needles. The incidence of postdural puncture headache by the paramedian approach is not significantly reduced whereas the spinal anesthesia failure rate is increased in comparison to the midline approach.

Prevention of postdural puncture headache after accidental dural puncture in cesarean sections: a comparative study

Background Accidental dural puncture (ADP) is one of the most common complications of neuraxial anesthesia in labor with high incidence of postdural puncture headache (PDPH). Aim Primary outcome: to compare the effectiveness of intramuscular neostigmine, intrathecal catheterization (ITC), epidural blood patch (EBP) on the prevention of PDPH. Secondary outcome: to assess the severity of PDPH and possible complications. Patients and methods One hundred and twenty patients exposed to ADP, fulfilling the inclusion criteria were divided into four equal groups. Control group: received conservative treatment when developed PDPH with a visual analog scale (VAS) of more than 4, group N: received intramuscular neostigmine 20 µg/kg and atropine 0.01 mg/kg after ADP, group ITC: ITC at the same site of ADP and left for 48 h and group EBP: received EBP at a level of ADP. VAS was assessed at 6, 12, 24, 36, and 24 h. Pain severity was divided into no pain (VAS 7). Number of patients who required rescue ketorolac analgesia and average diclofenac (mg) consumption during the first 48 h and possible complications were recorded. Results VAS score and pain severity were significantly higher in the control group than other groups, in group N and group ITC than EBP and in group N than group ITC at all examination times. The number of patients who required diclofenac analgesia was significantly higher in the control group than other groups. Average diclofenac consumption during the first 48 h was significantly higher in the control group than other groups, in both group ITC and group N than EBP and in group N than group ITC. Urinary bladder spasm, hypotension, and bradycardia were significantly higher in group N than other groups, and muscle twitching and abdominal cramps were significantly higher in group N than both control and EBP groups. Conclusion EBP was superior to ITC and neostigmine in reducing the incidence of PDPH and pain severity with less complications.

Continuous spinal anaesthesia for caesarean section in a patient with peripartum cardiomyopathy.

Continuous spinal anaesthesia for caesarean section in a patient with peripartum cardiomyopathy.

Atraumatic Versus Conventional Lumbar Puncture Needles: A Systematic Review and Meta-Analysis

(Lancet. 2018;391:1197–204) Among patients who undergo lumbar puncture, up to 35% return to the hospital with a postdural puncture headache, which is caused by continuing leakage of the cerebrospinal fluid (CSF) from the dural defect created by the spinal needle. Conventional needles are most frequently used in clinical practice by nonanesthesiologists and have a sharp slanted tip designed to cut through the dura with a distal opening for injection of drugs or collection of CSF. As these needles cut through tissues, they cause irregular lacerations that can increase the potential for CSF leakage. In contrast, atraumatic needles are blunt with a closed pencil point tip and a side port for drug injection or CSF collection. They separate and dilate dural fibers rather than cutting through the fibers; thus they have been postulated to reduce the incidence of postdural puncture headache because they limit the leakage of CSF after lumbar puncture. Although atraumatic needles are now commonly used by anesthesiologists for spinal anesthesia, they are infrequently used by other clinicians as they seem unaware of their existence. This systematic review and meta-analysis of randomized controlled trials was performed to compare atraumatic and conventional lumbar puncture needles.

Atraumatic lumbar puncture needles are associated with fewer complications than conventional needles.

Study question : Are atraumatic lumbar puncture (LP) needles associated with lower complications rates than conventional needles?1 Study design : Systematic review and meta-analysis of randomised control trials comparing atraumatic needles and conventional needles for LP (for any indication). LPs without a dural puncture (epidural injections) were excluded. The review was registered prospectively. Population: A total of 110 trials with 31 412 participants over a 28-year period (1989 to 2017). The mean age of participants was 38.6 years (SD 17.4) and 61.7% were women. Outcomes considered: Incidence of postdural puncture headaches (PDPH) as defined by the …

Clinical Comparative study of the effect of preoperative pregabalin on reduction of the incidence of headache after spinal anesthesia in cesarean section

Background: Post dural puncture headache (PDPH) is unpleasant complication following dural puncture. Incidence of PDPH following dural puncture range from 0.3% to 20% in spinal anesthesia. The incidence rate of PDPH is related to age, gender, needle size, pregnancy and previous history of PDPH.PDPH is characterized by severe, dull non throbbing pain aggravated by sitting or erect position, coughing, sneezing or straining and diminished in supine position. Objective: To evaluate the effect of preoperative administration of oral pregabalin (150 mg) before cesarean section on the incidence of post dural puncture headache, postoperative nausea and vomiting and postoperative shivering, motor block, time to rescue analgesia, time of two segment regression and Apgar score of baby at 1 and 5 minute. Patients and Methods: A prospective randomized study that was done in Alazhar University Hospitals after approval of ethical committee, An informed consent was obtained from the patients. Results: The incidence of post dural puncture headache, postoperative nausea and vomiting and postoperative shivering were significantly lower at pregabalin groups. Time to rescue analgesia and time of two segment regression were significantly longer at pregabalin groups. Patients at pregabalin groups reach modified Bromage motor scale grade 3 earlier than patients at groups without pregabalin. Conclusion: Preoperative oral pregabalin 150 mg before cesarean section reduced the incidence of PDPH, postoperative nausea and vomiting and postoperative shivering, beside the earlier onset of motor block with increase duration of analgesia and time of two segment regression with no effect on baby.

Effect of pre-administration with aminophylline on the occurrence of post-dural puncture headache in women undergoing caesarean section by combined spinal-epidural anaesthesia.

ObjectiveTo investigate the effect of the pre-administration with aminophylline on the occurrence of post-dural puncture headache (PDPH) in women undergoing caesarean section by combined spinal-epidural anaesthesia (CSEA).MethodsThe study enrolled women undergoing elective caesarean sections with CSEA and randomly allocated them into two groups; for 30 min immediately after the infant was delivered, group A received 250 mg aminophylline intravenously and group B received an equal volume of normal saline. Demographic data, operation time, intraoperative blood loss, intraoperative transfusion volume and the occurrence of PDPH during the first 7 days after the operation were recorded. Side-effects such as hypersensitivity, convulsion and arrhythmia were also recorded in the patients and infants in group A within 24 h after aminophylline administration.ResultsA total of 120 patients aged 24–38 years (pregnancy range, 38–42 weeks) were randomly allocated into two groups (n = 60). The incidence of PDPH in group A was significantly lower than group C (two of 59 [3.4%] versus 10 of 58 [17.2%], respectively). There were no related side-effects within 24 h after aminophylline administration in group A.ConclusionsIntraoperative intravenous infusion of 250 mg aminophylline reduced the incidence of PDPH after caesarean section under CSEA with no side-effects.

THUR 264 Multimodal intervention to improve lumbar puncture

IntroductionLumbar puncture (LP) is a routine procedure performed for diagnostic and therapeutic indications for more than 120 years.1 For as long, post-dural puncture headache (PDPH) has been a complication that can be persistent and severe.2 Finer gauge needles and ‘atraumatic’ needle designs3 significantly reduce the incidence of PDPH.4–6MethodsA multimodal intervention consisting of teaching session on atraumatic needle usage, simulation training with 25G Sprotte needles, and electronic LP proforma was introduced in October 2017.Records for all patients having LP in the Neurology day-case unit at the John Radcliffe Hospital, Oxford, in the months of November 2016 and Nov/Dec 2017 were retrospectively reviewed for documentation and atraumatic needle usage.Results39 records were reviewed from Nov/Dec 2017 and 16 from November 2016. Documentation was significantly improved across all criteria assessed except for documentation of informed consent. Atraumatic needle usage increased from none documented pre-intervention to 38% (n=11 out of 29 where atraumatic needle indicated) post intervention.ConclusionProforma use was associated with improved LP documentation. Atraumatic needle usage increased significantly post-intervention. These results are consistent with previous studies on changing behaviour in LP technique in neurology.7 Large scope for further improvement exists.Abstract THUR 264 Figure 1

Electron Microscopy of Dural and Arachnoid Disruptions After Subarachnoid Block

(Reg Anesth Pain Med 2017;42:709–718) Postdural puncture headache (PDPH) is commonly explained by intracranial hypotension due to cerebrospinal fluid leakage. An association between larger size dural punctures and an increased incidence of PDPH has been widely accepted. It was generally believed that pencil-point type needles produced smaller dural lesions by allowing separation rather than cutting of the dural fibers, but this has not been supported by morphologic evidence. There has been little investigation on the morphology of dural lesions produced by spinal needles. This study aimed to study human meninges and the morphology of dura-arachnoid lesions produced by 27 G Whitacre and 29 G Quincke spinal needles. The study also sought to determine whether there was a correlation between the diameter of the lesions and the needles used. Finally, authors aimed to determine whether the lesion diameter was altered when the 29 G needle bevel was oriented vertically rather than horizontally.

Impact of spinal needle type on postdural puncture headache among women undergoing Cesarean section surgery under spinal anesthesia: A meta-analysis.

Spinal anesthesia is the most frequently performed anesthesia for cesarean section. The American Society of Anesthesiology recommends using pencil-point spinal needles (SNs) over cutting-bevel SNs to reduce postdural puncture headache (PDPH) in their practice guidelines for obstetric anesthesia. However, there is no meta-analysis addressing the impact of the type of SNs on PDPH among women undergoing Cesarean section surgery. We conducted a systematic review and meta-analysis including randomized controlled trials comparing the incidence of PDPH of pencil-point SNs with cutting-bevel SNs in patients undergoing Cesarean section with spinal anesthesia. A comprehensive search of PubMed, Cochrane Library, EMBASE, and CINAHL without using any language and time restrictions were performed. A total of 4936 patients from 20 studies (31 comparisons) were included. Pencil-point SN leads to reduced PDPH (risk ratio [RR] 0.33, 95% confidence intervals [CI] 0.25 to 0.45) and reduced requirement of epidural blood patch (RR=0.21, 95% CI 0.09 to 0.51) compared to cutting-bevel SN. The incidence of anesthesia failure, non-PDPH, backache, and other adverse effects was not statistically significantly difference between the two SNs. Overall quality of evidence was moderate to low. Using pencil-point SN appears to be beneficial for preventing PDPH in patients undergoing Cesarean section without increasing any potential adverse effects. Further research addressing the specific gauge of pencil-point SNs, which might further reduce the incidence of PDPH is highly desired.

Comparison of Incidence of Post-Dural Puncture Headache (PDPH) in Patients Undergoing Lower Uterine Segment Caesarean Section (LSCS) among Different Batches of Residents

Comparison of Incidence of Post-Dural Puncture Headache (PDPH) in Patients Undergoing Lower Uterine Segment Caesarean Section (LSCS) among Different Batches of Residents

The Impact of Spinal Needle Selection on Postdural Puncture Headache: A Meta-Analysis and Metaregression of Randomized Studies.

Potentially broadened indications for spinal anesthesia require increased understanding of the risk factors and prevention measures associated with postdural puncture headache (PDPH). This review is designed to examine the association between spinal needle characteristics and incidence of PDPH. Meta-analysis and metaregression was performed on randomized controlled trials to determine the effect of needle design and gauge on the incidence of PDPH after controlling for patient confounders such as age, sex, and year of publication. Fifty-seven randomized controlled trials (n = 16416) were included in our analysis, of which 32 compared pencil-point design with cutting-needle design and 25 compared individual gauges of similar design. Pencil-point design was associated with a statistically significant reduction in incidence of PDPH (risk ratio, 0.41; 95% confidence interval, 0.31-0.54; P < 0.001; I = 29%) compared with cutting needles among studies that assessed both design types. Subgroup analysis among obstetric and nonobstetric procedures yielded similar results. After adjustment for significant covariates, metaregression analysis among all 57 included trials revealed a significant correlation between needle gauge and rate of PDPH among cutting needles (slope = -2.65, P < 0.001), but not pencil-point needles (slope = -0.01, P = 0.819). Pencil-point needles are associated with significantly lower incidence of PDPH compared with the cutting-needle design. Whereas a significant relationship was noted between needle gauge and PDPH for cutting-needle design, a similar association was not shown for pencil-point needles. Providers may consider selection of larger-caliber pencil-point needle to maximize technical proficiency without expensing increased rates of PDPH.

Incidence and management of post-dural puncture headache following spinal anaesthesia and accidental dural puncture from a non-obstetric hospital: A retrospective analysis.

Background and Aims:Post-dural puncture headache (PDPH) is one of the complications following spinal anaesthesia (SA) and accidental dural puncture (ADP). In our institute, we routinely practice epidural analgesia (EA) for supra-major surgeries. Our previous audit on EA revealed 4% incidence of ADP. This lead us to a clinical initiative to follow-up patients with dural puncture (DP) to note the incidence, presentation, associated symptoms and treatment of PDPH. Herewith, we present the retrospective analysis over a 2-year period.Methods:Following institutional review board approval, the follow-up notes of patients who had DP from May 2011 to April 2013 were analysed retrospectively (using SPSS 20 version) with respect to the needle size, level of DP, reinsertion of epidural catheter, details of ongoing analgesics, incidence and severity of PDPH and treatment received.Results:In 2 years, we found that the incidence of PDPH in the patients who received SA was 3.9% and 25% in the ADP group. There was a positive association between needle size, type and PDPH, and it was seen more in the 20–40 age group. The commonest presentation of PDPH was occipital/frontal headache within 96 h and lasted for a mean of 3 days. All patients received pharmacological treatment. Seventy-one per cent of patients (25) were either on coffee or caffeine tablets. One case of intractable PDPH responded well to oral pregabalin 75 mg.Conclusion:PDPH severity and incidence following ADP in our centre is lower than the reported incidence from obstetric centres and can be effectively controlled with drug treatment only.