Review of the Alternatives to Epidural Blood Patch for Treatment of Postdural Puncture Headache in the Parturient

Optic nerve sheath diameter measurement for prediction of postdural puncture headache

PURPOSE

Intracranial hypotension due to cerebrospinal fluid leak is mainly the causal factor for the pathophysiology of postdural puncture headache (PDPH). In this study, we aimed to evaluate the effectiveness of optic nerve sheath diameter (ONSD) measurement in predicting the development of PDPH in patients undergoing spinal anesthesia.

METHODS

According to the American Society of Anesthesiology (ASA) physical classification I-III, 83 patients aged 18-65 years scheduled for spinal anesthesia for elective surgery were included in the study. Demographic data (age, ASA, sex, smoking, migraine, and PDPH history) and operative data were recorded. Preoperative ONSD measurements were taken in the right and left eye, axial, and sagittal planes. The mean of four measurements was recorded before and 24 h after the spinal anesthesia.

RESULTS

A total of 83 patients (59 males and 24 females) were included in the study. In our study, the rate of PDPH development was determined as 22.9% (n = 19). There was a statistically significant difference in the preoperative and postoperative ONSD values between patients with and without PDPH development (p = 0.046). In the receiver operating characteristic analysis, the area under the curve was 0.843, and the cutoff value was 0.4.

CONCLUSION

The difference between the ONSD values measured before and after spinal anesthesia may be an important parameter for predicting the risk of PDPH development.

Refractory primary and secondary headache disorders that dramatically responded to combined treatment of ultrasound-guided percutaneous suprazygomatic pterygopalatine ganglion blocks and non-invasive vagus nerve stimulation: a case series

In 1981, Devoghel achieved an 85.6% success rate in treating patients with treatment-refractory cluster headaches with alcoholization of the pterygopalatine ganglion (PPG) via the percutaneous suprazygomatic approach. Devoghel's study led to the theory that interrupting the parasympathetic pathway by blocking its transduction at the PPG could prevent or treat symptoms related to primary headache disorders (PHDs). Furthermore, non-invasive vagus nerve stimulation (nVNS) has proven to treat PHDs and has been approved by national regulatory bodies to treat, among others, cluster headaches and migraines.In this case series, nine desperate patients who presented with 11 longstanding treatment-refractory primary headache disorders and epidural blood patch-resistant postdural puncture headache (PDPH) received ultrasound-guided percutaneous suprazygomatic pterygopalatine ganglion blocks (PPGB), and seven also received nVNS. The patients were randomly selected and were not part of a research study. They experienced dramatic, immediate, satisfactory, and apparently lasting symptom resolution (at the time of the writing of this report). The report provides the case descriptions, briefly reviews the trigeminovascular and neurogenic inflammatory theories of the pathophysiology, outlines aspects of these PPGB and nVNS interventions, and argues for adopting this treatment regime as a first-line or second-line treatment rather than desperate last-line treatment of PDPH and PHDs.

Trans-nasal sphenopalatine ganglion block for post-dural puncture headache management: a meta-analysis of randomized trials

OBJECTIVE

To evaluate the efficacy and safety of trans-nasal Sphenopalatine Ganglion (SPG) block over other treatments for Post-Dural Puncture Headache (PDPH) management.

METHODS

A systematic literature search was conducted on databases for Randomized Controlled Trials (RCTs) comparing trans-nasal SPG blockade for the management of PDPH over other treatment modalities. All outcomes were pooled using the Mantel-Haenszel method and random effect model. Analyses of all outcomes were performed as a subgroup based on the type of control interventions (conservative, intranasal lignocaine puffs, sham, and Greater Occipital Nerve [GON] block). The quality of evidence was assessed using the GRADE approach.

RESULTS

After screening 1748 relevant articles, 9 RCTs comparing SPG block with other interventions (6 conservative treatments, 1 sham, 1 GON and 1 intranasal lidocaine puff) were included in this meta-analysis. SPG block demonstrated superiority over conservative treatment in pain reduction at 30 min, 1 h, 2 h, 4 h after interventions and treatment failures with "very low" to "moderate" quality of evidence. The SPG block failed to demonstrate superiority over conservative treatment in pain reduction beyond 6 h, need for rescue treatment, and adverse events. SPG block demonstrated superiority over intranasal lignocaine puff in pain reduction at 30 min, 1 h, 6 h, and 24 h after interventions. SPG block did not show superiority or equivalence in all efficacy and safety outcomes as compared to sham and GON block.

CONCLUSION

Very Low to moderate quality evidence suggests the superiority of SPG block over conservative treatment and lignocaine puff for short-term pain relief from PDPH.

PROSPERO REGISTRATION

CRD42021291707.

Evidence-based clinical practice guidelines on postdural puncture headache: a consensus report from a multisociety international working group

INTRODUCTION

Postdural puncture headache (PDPH) can follow unintentional dural puncture during epidural techniques or intentional dural puncture during neuraxial procedures such as a lumbar puncture or spinal anesthesia. Evidence-based guidance on the prevention, diagnosis or management of this condition is, however, currently lacking. This multisociety guidance aims to fill this void and provide practitioners with comprehensive information and patient-centric recommendations to prevent, diagnose and manage patients with PDPH.

METHODS

Based on input from committee members and stakeholders, the committee cochairs developed 10 review questions deemed important for the prevention, diagnosis and management of PDPH. A literature search for each question was performed in MEDLINE (Ovid) on 2 March 2022. The results from each search were imported into separate Covidence projects for deduplication and screening, followed by data extraction. Additional relevant clinical trials, systematic reviews and research studies published through March 2022 were also considered for the development of guidelines and shared with contributors. Each group submitted a structured narrative review along with recommendations graded according to the US Preventative Services Task Force grading of evidence. The interim draft was shared electronically, with each collaborator requested to vote anonymously on each recommendation using two rounds of a modified Delphi approach.

RESULTS

Based on contemporary evidence and consensus, the multidisciplinary panel generated 50 recommendations to provide guidance regarding risk factors, prevention, diagnosis and management of PDPH, along with their strength and certainty of evidence. After two rounds of voting, we achieved a high level of consensus for all statements and recommendations. Several recommendations had moderate-to-low certainty of evidence.

CONCLUSIONS

These clinical practice guidelines for PDPH provide a framework to improve identification, evaluation and delivery of evidence-based care by physicians performing neuraxial procedures to improve the quality of care and align with patients' interests. Uncertainty remains regarding best practice for the majority of management approaches for PDPH due to the paucity of evidence. Additionally, opportunities for future research are identified.

Caffeine for Headaches: Helpful or Harmful? A Brief Review of the Literature

Consumption of caffeine in the diet, both daily and occasional, has a significant biological effect on the nervous system. Caffeine, through various and not yet fully investigated mechanisms, affects headaches. This is especially noticeable in migraine. In other headaches such as hypnic headache, post-dural puncture headache and spontaneous intracranial hypotension, caffeine is an important therapeutic agent. In turn, abrupt discontinuation of chronically used caffeine can cause caffeine-withdrawal headache. Caffeine can both relieve and trigger headaches.

Post-dural puncture headache accompanied by obvious nasal congestion: A case report

INTRODUCTION

Post-dural puncture headache (PDPH) is the most common complication of intraspinal nerve block in gravida. PDPH may be accompanied by neck stiffness, tinnitus, hearing loss, photophobia or nausea.

PATIENT CONCERNS

A 33-year-old woman whose dura was accidentally punctured during labor analgesia complained of severe headache, dizziness, and nasal congestion; these symptoms aggravated when she looked up, and her sense of smell was normal 8 hours after catheter removal.

DIAGNOSES

Based on the patient's complaints and clinical appearance, diagnosis of PDPH was considered.

INTERVENTIONS

Nasal congestion disappeared with headache and dizziness after epidural injections of saline. The puerpera received saline injections 4 times; after treatment, she was discharged from the hospital when the symptoms did not limit her daily movement.

OUTCOMES

The symptoms disappeared completely on the seventh day of telephone follow-up visit. The mechanism of her nasal obstruction is not very clear.

CONCLUSION

We believe it is caused by the pulling of the intracranial nerve as the brain tissue sinks and shifts due to the decrease in intracranial pressure.

Post-dural puncture headache prevention and treatment with aminophylline or theophylline: a systematic review and meta-analysis

BACKGROUND

Post-dural puncture headache (PDPH) is one of the most common complications in patients undergoing spinal anesthesia. The present systematic review and meta-analysis aimed to assess the therapeutic and prophylactic effects of aminophylline and theophylline on PDPH.

METHODS

Relevant studies were identified by searching the following electronic databases, without language restriction, until June 2020: Scopus, EMBASE, MEDLINE, Google Scholar, Web of Science, Cochrane Library-CENTRAL, and CINAHL Complete. Random effects models were used to calculate the standardized mean difference (SMD) and risk ratios (RRs) with 95% confidence intervals (95% CI) to assess the therapeutic and prophylactic effects of aminophylline and theophylline on PDPH, respectively. The Cochrane tool was used for the quality assessment of the included studies. The certainty of the evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation method.

RESULTS

Of the 1,349 initial records, 15 met our eligibility criteria (6 studies on therapeutic and 9 on prophylactic effects). A significant reduction in the pain score was observed following aminophylline/theophylline treatment (SMD = -1.67; 95% CI, -2.28 to -1.05; P < 0.001, I2 = 84.7%; P < 0.001). Subgroup analysis revealed that the therapeutic effect was significantly higher when these agents were compared to placebo than when conventional therapies were used. The risk of PDPH after aminophylline administration was not significantly reduced (RR = 0.74; 95% CI, 0.42 to 1.31; P = 0.290).

CONCLUSIONS

Theophylline and aminophylline have therapeutic, but not prophylactic, effects on PDPH.

Does an Epidural Blood Patch (EBP) for Postdural Puncture Headache (PDPH) From a Lumbar Spinal Drain Necessitate a Distinct Approach?

An intentional or unintentional dural puncture puts patients at significant risk for a postdural puncture headache (PDPH). When conservative treatments fail, an epidural blood patch (EBP) is offered cautiously due to rare but devastating complications. The literature is abundant with reviews on the management of PDPH in obstetric patients, but there is a paucity of data on the management of PDPH and complications of EBP in patients post spinal drain placement. In this case report, we address the specific concerns that vascular patients may have about the outcomes of large needle sizes and suggest alternative approaches for non-obstetric patients.

Postpartum posterior reversible encephalopathy syndrome secondary to preeclampsia and cerebrospinal fluid leakage: A case report and literature review

BACKGROUND

Postpartum posterior reversible encephalopathy syndrome (PRES) is not uncommon. Its mechanisms and risk factors are not clear.

CASE SUMMARY

A 28-year-old woman underwent cesarean section but had inadvertent dural puncture during epidural anesthesia. To manage the symptoms of intracranial hypotension, crystalloid fluid was infused. However, the patient developed postpartum preeclampsia and PRES. The patient was treated with diazepam and dehydration therapy. The signs of cerebral lesions on magnetic resonance imaging disappeared on postpartum day 7.

CONCLUSION

Postpartum preeclampsia and PRES can develop concomitantly. Treating postdural puncture headaches with infusion of crystalloid fluid may precipitate the development of PRES.

[Postdural puncture headache in obstetrics : Pathogenesis, diagnostics and treatment]

Postdural puncture headache (PDPH) is one of the most important complications of peripartum neuraxial analgesia. Loss of cerebrospinal fluid volume and pressure as well as compensatory intracranial vasodilation are assumed to be responsible. Potentially severe long-term sequelae necessitate the correct diagnosis of PDPH, exclusion of relevant differential diagnoses (with atypical symptoms and when indicated via imaging techniques) and rapid initiation of effective treatment. Nonopioid analgesics, caffeine and occasionally theophylline, gabapentin and hydrocortisone are the cornerstones of pharmacological treatment, while the timely placement of an autologous epidural blood patch (EBP) represents the gold standard procedure when symptoms persist despite the use of analgesics. Procedures using neural treatment are promising alternatives, especially when an EBP is not desired by the patient or is contraindicated. Interdisciplinary and interprofessional consensus standard procedures can contribute to optimization of the clinical management of this relevant complication.

Treating Spontaneous Intracranial Hypotension with an Anesthetic Modality: The Role of the Epidural Blood Patch

Background: Spontaneous intracranial hypotension (SIH) is a rare syndrome characterized by heterogeneity of presentation and prognosis, which can occasionally result in serious complications, such as the formation of subdural hematomas (SDHs). This case series aims to emphasize that SIH remains a diagnostic and therapeutic challenge; it can present with a broad clinical spectrum of symptoms, can lead to SDH and, if conservative treatment fails, an epidural blood patch (EBP) is a viable treatment option. Although the exact etiology of SIH is not known, it is believed to be due to cerebrospinal fluid (CSF) leak or a low CSF pressure. Case Series: Three patients (two males and one female) with ages ranging between 38 and 53 years old who presented with complaints of not only an orthostatic headache, but also a variety of symptoms of SIH, including the formation of two SDHs in one of them, were included in this series. These patients did not respond to conservative management and, subsequently, given the clinical and radiological evidence of SIH, were referred to the Anesthesiology Department for an EBP. Diagnostic workup was facilitated by imaging modalities, including magnetic resonance imaging (MRI) of the brain and spinal cord, prior to the EBP. All three patients were subjected to an EBP with an 18-gauge epidural needle. A total of between 30 and 43 mL of autologous blood was collected from the patients and was injected into the epidural space under strict aseptic conditions. Two lumbar (L₁-L₂, L₂-L₃) EBPs and one thoracic (T₁₁-T₁₂) EBP were performed on the three patients, respectively. All patients reported complete resolution of symptoms following the EBPs, while MRI improved substantially. Conclusions: This report describes three cases of SIH with CSF leak originating from the cervical, the thoracic and the lumbar level. The EBP restored CSF pressure and relieved the patients' persistent symptoms. MRI helps in revealing indirect signs of a low volume of CSF, though it may not be possible to locate the actual site of the leak. In conclusion, EBP is a well-accepted and beneficial treatment modality for SIH when conventional measures fail.

Postdural Puncture Headache-Risks and Current Treatment

PURPOSE OF REVIEW

This manuscript aims to review the risks and the current treatments for postdural puncture headache (PDPH).

RECENT FINDINGS

PDPH is a relatively frequent complication after neuraxial blocks. It is typically orthostatic in nature, presenting as a positional and dull aching or throbbing headache, with added dysregulation of auditory and/or visual signals. Certain characteristics, such as female sex and young age, may predispose patients to the development of PDPH, as may factors such as previous PDPH, bearing down during the second stage of labor, and the neuraxial technique itself. Long-term complications including chronic headache for years following dural puncture have brought into question of the historical classification of PDPH as a self-limiting headache. So far, the underlying mechanism governing PDPH remains under investigation, while a wide variety of prophylactic and therapeutic measures have been explored with various degree of success. In case of mild PDPH, conservative management involving bed rest and pharmacological management should be used as first-line treatment. Nerve blocks are highly efficient alternatives for PDPH patients who do not respond well to conservative treatment. In case of moderate-to-severe PDPH, epidural blood patch remains the therapy of choice. An interdisciplinary approach to care for patients with PDPH is recommended to achieve optimal outcomes.

It is wrong to treat pain in CSF hypotension headache to allow the patient to walk!

It is wrong to treat pain in CSF hypotension headache to allow the patient to walk!

Prone position: A possible method to decrease post dural puncture headache (PDPH) during surgery

OBJECTIVES

Postdural puncture headache (PDPH) is a complication associated with spinal and epidural anesthesia, characterized by a very severe dull, non-throbbing positional headache along with nausea, vomiting and other symptoms. The aim of this study was to compare positional character of PDPH, where the effects of prone and supine positions during surgery were compared for the risk of the headache.

METHODS

This cohort study, was carried out at (XXX) University of Medical Sciences from June 2019 to June 2020 after the approval from the Ethical Committee. 1416 patients participated in this study among whom either supine or prone positions were used for the surgery, based on the type of surgical requirements. All patients received spinal where, 18-gauge cannula was inserted and lactated ringer 4 mL per Kg per hour was used for the administration. Using an aseptic technique, a 26-gauge Quincke needle was inserted intrathecally via a midline approach into the L3-L4 or L4-L5 interspace with the patient in the sitting position. Patients received 10 mg 0.5% hyperbaric bupivacaine. 444 patients were operated in the prone position during surgery (P group) and the 972 patients were in the supine position (S group).

RESULTS

We compared the rate of PDPH between the two groups. 3 (0.68%) patients with pilonidal sinus were operated in prone position experienced headache and 87 of those operated in supine position (8.95%) had headache (P < 0.001); and the odds ratio of developing headache when operated in supine position was 13.16.

CONCLUSIONS

Prone position during surgery appears to be a reliable way to reduce PDPH following spinal or epidural anesthesia.

Recent update on epidural blood patch

Epidural blood patch (EBP) is the injection of autologous blood into the epidural space with the intent of sealing off a dural tear and stopping the leakage of cerebrospinal fluid (CSF). EBP may cause an increase in intracranial pressure due to the mass effect of the injected blood volume, causing CSF from the spinal compartment to enter the intracranial compartment. EBP is usually considered in the management of moderate to severe headache (HA) attributed to low CSF pressure, such as post-dural puncture HA (PDPH), CSF fistula HA, and HA attributed to spontaneous intracranial hypotension (SIH) that does not respond to conservative management. However, prophylactic administration of EBP after accidental dural puncture can hardly be substantiated at present. EBP is generally safe but may rarely be associated with serious complications. Therefore, it should be carefully planned and performed under C-arm fluoroscopic guidance. Although many studies on PDPH and SIH have been conducted until recently, only few reviews have summarized the effectiveness of EBP from the perspective of a pain physician. This article reviews the current literature on the indication, contraindication, procedural consideration, post-procedural management, outcomes, and complications of EBP and the considerations for EBP in patients with COVID-19.

Efficacy of greater occipital nerve block for pain relief in patients with postdural puncture headache: A meta-analysis

BACKGROUND

This study aimed at assessing the therapeutic effectiveness of greater occipital nerve block (GONB) against postdural puncture headache (PDPH).

METHODS

Studies investigating analgesic effects of GONB against PDPH in adults were retrieved from the MEDLINE, EMBASE, Google scholar, and Cochrane central databases from their inception dates to May, 2021. Pain score at postprocedural 24 hours was the primary endpoint, while secondary endpoints were pain score at postprocedural 1 hour and 12 hours as well as the risk of intervention failure.

RESULTS

Of the 7 studies (randomized controlled trials [RCTs], n = 4; non-RCTs, n = 3) that recruited 275 patients, 2 investigated female patients undergoing cesarean section and the other 5 were conducted in both obstetric and nonobstetric settings. Pooled results showed a lower mean pain score at 24 hours (i.e., primary outcome) (mean difference [MD] = -2.66, 95%: CI: -3.98 to -1.33, P < .001; I2 = 97%, 6 studies), 1 hour (MD = -4.23, 95% confidence interval [CI]: -5.08 to -3.37, P < .00001; I2 = 86%, 5 studies), and 6 hours (MD = -2.78, 95% CI: -4.99 to -0.57, P = .01; I2 = 98%, 4 studies) in patients with GONB compared to those without. Trial sequential analysis supported the robustness of evidence at postprocedural 24 hours. The use of GONB also decreased the risk of intervention failure (relative ratio [RR] = 0.4, 95% CI: 0.19 to 0.82, P = .01; I2 = 96%, 6 studies, 277 patients).

CONCLUSION

Our results suggested a therapeutic effect of greater occipital nerve block against postdural puncture headache up to postprocedural 24 hours. Further large-scale studies are warranted to evaluate its therapeutic benefit beyond the acute stage.

The impact of aminophylline on incidence and severity of post-dural puncture headache: A meta-analysis of randomised controlled trials

BACKGROUND

This meta-analysis aimed at addressing the impact of aminophylline use on risk and severity of post-dural puncture headache (PDPH).

METHODS

Electronic databases (i.e., Medline, Embase, and the Cochrane controlled trials register) were searched from inception to the 12^th of January 2021 for randomised controlled trials (RCTs) that assessed the efficacy of aminophylline for treatment (i.e., primary outcome) or prophylaxis (i.e., secondary outcome) against PDPH in various clinical settings. The study is registered with PROSPERO (CRD42020207713).

RESULTS

A total of ten RCTs (n = 976) were included for analysis. Five studies (n = 270) revealed a lower pain score in patients with PDPH receiving aminophylline than that in the placebo group (standardised mean differences = -1.34, 95% confidence interval (CI): -1.76 to -0.91). In contrast, five trials (four on Caesarean sections and one on lower extremity surgeries, n = 706) demonstrated no prophylactic effect of aminophylline against PDPH at 24 [risk ratio (RR) = 0.70, 95% CI: 0.30-1.63, n = 637], 48 (RR = 0.48, 95% CI: 0.22-1.05, n = 506), and 72 (RR = 0.89, 95% CI: 0.54-1.48, n = 317) hours. Nevertheless, sensitivity analysis demonstrated significant prophylactic efficacy after removal of one study adopting a relatively low dose of aminophylline (RR = 0.36, 95% CI: 0.19-0.67). Most studies reported no increase in the incidence of adverse events associated with aminophylline use compared with that in the control group.

CONCLUSION

Our results indicated that aminophylline might be a reasonable alternative for treating PDPH. However, its use for prevention was not established in this meta-analysis and further large-scale studies are warranted to support this option.

New approaches and therapeutic options for post-dural puncture headache treatment

Post-dural puncture headache (PDPH) is a frequent complication in neuraxial approaches. It may result in disability, healthcare dissatisfaction and potentially serious complications. The traditional initial management includes general and analgesia measures with poor evidence. The treatment approach best supported by the literature is the epidural blood patch for which rates of up 70% improvement have been reported. Regional techniques have been recently described that may be helpful because they are less invasive than the epidural blood patch, under certain clinical circumstances. This article suggests an algorithm that uses such techniques for the management of this complication.

[Postdural puncture headache after neuraxial anesthesia: incidence and risk factors]

Hintergrund/Ziel der Arbeit

Der postpunktionelle Kopfschmerz (PKS) ist eine Komplikation nach rückenmarknahen Verfahren (RA) mit erheblichem Krankheitswert. Ziel der Untersuchung war es, die Inzidenz des PKS in 2 großen operativen Kollektiven zu untersuchen, mögliche Risikofaktoren zu identifizieren und den Einfluss auf die Krankenhausverweildauer zu untersuchen.

Material und Methoden

In einer retrospektiven Analyse des Zeitraums 2010–2012 wurden 341 unfallchirurgische (UCH) und 2113 geburtsmedizinische (GEB) Patient*innen nach Spinalanästhesie (SPA) analysiert. In der statistischen Auswertung (SPSS-23) kamen univariate Analysen mittels Mann-Whitney-U-, Chi²- und Student’s t‑Test sowie logistische Regressionsanalysen zur Anwendung.

Ergebnisse

Die Inzidenz des PKS betrug in der UCH-Gruppe 5,9 % und in der GEB-Gruppe 1,8 %. Patient*innen mit PKS in der UCH wiesen ein jüngeres Patientenalter (38 vs. 47 Jahre, p = 0,011), einen geringeren BMI (23,5 vs. 25,2, p = 0,037) sowie ein niedrigeres Köpergewicht (70,5 kg vs. 77 kg, p = 0,006) als Patient*innen ohne PKS auf. Dabei konnten das Alter mit einer „odds ratio“ (OR 97,5 % Konfidenzintervall [KI]) von 0,963 (97,5% KI 0,932–0,991, p = 0,015) und das Köpergewicht mit einer OR von 0,956 (97,5 % KI 0,920–0,989, p = 0,014) als unabhängige Risikofaktoren für die Entstehung eines PKS identifiziert werden. In der GEB wies die SPA eine höhere Inzidenz des PKS auf als die kombinierte Spinalepiduralanästhesie (CSE) (8,6 % vs. 1,2 %, p < 0,001). Dabei erwies sich das Verfahren mit einer OR von 0,049 (97,5 % KI 0,023–0,106, p < 0,001) als unabhängiger Risikofaktor für die Entstehung eines PKS. In beiden Gruppen war der PKS mit einem verlängerten Krankenhausaufenthalt assoziiert (UCH-Gruppe 4 vs. 2 Tage, p = 0,001; GEB-Gruppe 6 vs. 4 Tage, p < 0.0005).

Diskussion

Die Inzidenz des PKS nach SPA/CSE war in unserer Untersuchung in den beschriebenen Patientengruppen unterschiedlich, mit einem deutlich höheren Anteil in der UCH-Gruppe. Alter, Konstitution und Verfahren waren hinweisgebende Risikofaktoren eines PKS. In Anbetracht der funktionellen Einschränkungen (Mobilisation, Versorgung des Neugeborenen) und des verlängerten Krankenhausaufenthalts, sollten zukünftige Studien eine frühe Behandlung des PKS untersuchen.