Parasacral Ischial Plane Block in Lower Extremity Surgery

Evaluation of Sensory and Motor Blockade of Ultrasound-Guided Parasacral Ischial Plane Block in Lower Extremity Surgery

The parasacral ischial plane block is a novel fascial plane approach targeting the sacral plexus. This technique is technically less challenging and eliminates the requirement for direct visualization of the sacral plexus. The aim of this prospective observational study is to evaluate the efficacy of the conventional sacral plexus block versus the parasacral ischial plane block in patients undergoing lower extremity surgery.

Study Overview

• Status: Not yet recruiting
• Conditions: Patients Scheduled for Elective Lower Extremity Surgery; Ages 18-80; ASA I-III; Patients Operated on Under Regional Anesthesia; Patients Who Provided Written Informed Consent
• Intervention / Treatment: Procedure: Parasacral Ischial Plan Block; Procedure: Sacral plexus block

Detailed Description

Sympatholysis resulting from central neuraxial block or general anesthesia in lower extremity surgeries may lead to adverse hemodynamic changes and increased perioperative mortality, particularly in high-risk patients. In such patients, lower extremity procedures can be successfully performed solely under sciatic and femoral nerve blocks. Depending on the surgical indication, the sciatic nerve block may be utilized alone or in combination with a lumbar plexus or femoral nerve block.A novel ultrasound-guided (USG) fascial plane approach targeting the sacral plexus, termed the Parasacral Ischial Plane (PIP) block, has been successfully investigated in a limited number of patients. The sacral plexus is located within a fascial plane formed by the pelvic fascia anteriorly, the sacrum medially, the piriformis and gluteus maximus muscles posteriorly, and the ischium bone laterally. The piriformis muscle has no attachment to the ischium; instead, it attaches laterally to the greater trochanter. A fascial plane exists between the piriformis muscle and the ischium, which extends directly to the sacral plexus.

Venkataraju et al. stated that during the demonstration of the PIP block, the needle should be directed and positioned toward the posteromedial surface of the ischium. Following bony contact, the injectate was administered, and its spread was observed beneath the piriformis muscle toward the sacral plexus (SP). This method is considered to be technically more straightforward and carries a lower risk profile.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: NURULLAH DAMLA; Phone Number: +905075482122; Email: nurullahdamla@hotmail.com
• Study Contact Backup: Name: Korgün Ökmen, professor; Phone Number: +905057081021; Email: korgunokmen@gmail.com

Study Locations

• Turkey (Türkiye)
  • Yildirim
    • Bursa, Yildirim, Turkey (Türkiye), 16300
      • Bursa High Specialization Training and Research Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Ages 18-80
2. ASA I-III
3. Patients operated on under regional anesthesia
4. Patients who provided written informed consent
5. Patients scheduled for elective lower extremity surgery -

Exclusion Criteria:

1. Patients with a history of allergy to local anesthetic drugs
2. Patients with coagulation disorders
3. Patients with BMI > 40 kg/m²
4. Presence of infection at the block application site
5. Chronic pain syndrome (chronic opioid use)
6. Pregnant women
7. Patients who cannot be communicated with
8. Patients requiring emergency surgery -

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Parasacral Ischial Plan Block; A novel ultrasound-guided fascial plane approach to the sacral plexus, called the Parasacral-Ischial Plane (PIP) block, has been successfully studied in a small number of patients. The sacral plexus is located within a fascial plane formed by the pelvic fascia anteriorly, the sacrum medially, the piriformis and gluteus maximus muscles posteriorly, and the ischium laterally. The piriformis muscle has no attachment to the ischium and attaches to the greater trochanter laterally. A fascial plane exists between the piriformis muscle and the ischium; this fascial plane extends to the sacral plexus. Venkataraju et al. stated that in a PIP block demonstration, the needle should be directed and placed towards the posteromedial surface of the ischium. After bone contact, medication was injected, and it was observed that the medication spread from under the piriformis muscle towards the sacral plexus. This method is considered easier and less risky.	Procedure: Parasacral Ischial Plan Block; The sacral plexus is located within a fascial plane formed by the pelvic fascia anteriorly, the sacrum medially, the piriformis and gluteus maximus muscles posteriorly, and the ischium laterally. The piriformis muscle has no attachment to the ischium and attaches to the greater trochanter laterally. A fascial plane exists between the piriformis muscle and the ischium; this fascial plane extends to the sacral plexus. Venkataraju et al. stated that in PIP block demonstrations, the needle should be directed and placed towards the posteromedial surface of the ischium. After bone contact, the medication was injected, and it was observed that the medication spread from under the piriformis muscle towards the sacral plexus.
Active Comparator: Sacral plexus block; This block, defined by the parasacral approach, targets the exit point of the plexus at the level of the foramen ischiadicum majus. Unlike distal sciatic blocks, blocking at this level includes the posterior cutaneous femoral nerve, superior/inferior gluteal nerve, and pudendal nerve, along with the ischial nerve. In current practice, ultrasonography (USG) has become the "gold standard"; visualizing the neural structures deep to the piriformis muscle by placing the probe between the lateral sacrum and the iliac wing increases the success rate while minimizing the risk of complications.	Procedure: Sacral plexus block; This block, defined by the parasacral approach, targets the exit point of the plexus at the level of the foramen ischiadicum majus. Unlike distal sciatic blocks, blocking at this level includes the posterior cutaneous femoral nerve, superior/inferior gluteal nerve, and pudendal nerve, along with the ischial nerve. In current practice, ultrasonography (USG) has become the "gold standard"; visualizing the neural structures deep to the piriformis muscle by placing the probe between the lateral sacrum and the iliac wing increases the success rate while minimizing the risk of complications.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sensory and motor block onset time	This approach is based on the volume-dependent spread of local anesthetic into the plane between the sacral plexus and the deep pelvic muscle fascia; sensory blockade begins proximally to distally within 10-20 minutes, while motor blockade usually develops later and gradually around 20-30 minutes.	1 hour

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The Numerical Rating Scale (NRS)	Pain control is a one-dimensional measurement tool, usually ranging from 0 to 10, used to subjectively assess a patient's pain intensity. In academic literature, this scale, expressed with integers from 0 (no pain) to 10 (the most severe pain imaginable), is considered a fundamental parameter for pain monitoring in clinical research and perioperative processes due to its high validity, ease of application, and flexibility in verbal or written form.	1 Day

Collaborators and Investigators

• Sponsor: Bursa Yuksek Ihtisas Training and Research Hospital
• Investigators: Study Director: Korgün Ökmen, Bursa Yuksek Ihtisas Training and Research Hospital

Publications and helpful links

General Publications

• Enneking FK, Chan V, Greger J, Hadzic A, Lang SA, Horlocker TT. Lower-extremity peripheral nerve blockade: essentials of our current understanding. Reg Anesth Pain Med. 2005 Jan-Feb;30(1):4-35. doi: 10.1016/j.rapm.2004.10.002. No abstract available.
• Zhao J, Huang Y, Fu M, Tao F. Ultrasound-guided suprainguinal fascia iliaca block combined with a sacral plexus block for lower extremity surgery: A case report. Medicine (Baltimore). 2020 Aug 28;99(35):e21921. doi: 10.1097/MD.0000000000021921.
• Arjun BK, Prijith RS, Sreeraghu GM, Narendrababu MC. Ultrasound-guided popliteal sciatic and adductor canal block for below-knee surgeries in high-risk patients. Indian J Anaesth. 2019 Aug;63(8):635-639. doi: 10.4103/ija.IJA_296_19.
• Chia N, Low TC, Poon KH. Peripheral nerve blocks for lower limb surgery--a choice anaesthetic technique for patients with a recent myocardial infarction? Singapore Med J. 2002 Nov;43(11):583-6.
• Bech B, Melchiors J, Borglum J, Jensen K. The successful use of peripheral nerve blocks for femoral amputation. Acta Anaesthesiol Scand. 2009 Feb;53(2):257-60. doi: 10.1111/j.1399-6576.2008.01859.x.
• Venkataraju A, Narayanan M, Phillips S. Parasacral ischial plane (PIP) block: An easy approach to sacral plexus. J Clin Anesth. 2020 Feb;59:103-105. doi: 10.1016/j.jclinane.2019.06.030. Epub 2019 Jul 16. No abstract available.

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): May 1, 2027

Study Registration Dates

• First Submitted: May 5, 2026
• First Submitted That Met QC Criteria: May 14, 2026
• First Posted (Actual): May 18, 2026

Study Record Updates

• Last Update Posted (Actual): May 18, 2026
• Last Update Submitted That Met QC Criteria: May 14, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Postoperative Pain; Anesthesia, Conduction; Lumbosacral Plexus
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative
• Other Study ID Numbers: BursaYIERH-AR-ND-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: due to patient privacy

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No