Deep gluteal syndrome describes the non- discogenic extrapelvic

entrapment Entrapment is a practice in which a law enforcement agent or an agent of the state induces a person to commit a crime that the person would have otherwise been unlikely or unwilling to commit.''Sloane'' (1990) 49 A Crim R 270. See also agent prov ...

of the

sciatic nerve The sciatic nerve, also called the ischiadic nerve, is a large nerve in humans and other vertebrate animals. It is the largest branch of the sacral plexus and runs alongside the hip joint and down the right lower limb. It is the longest and widest ...

in the deep gluteal space. In simpler terms this is

sciatica Sciatica is pain going down the leg from the lower back. This pain may go down the back, outside, or front of the leg. Onset is often sudden following activities such as heavy lifting, though gradual onset may also occur. The pain is often desc ...

due to nerve irritation in the buttocks rather than the spine or pelvis. It is an extension of non-discogenic sciatic nerve entrapment beyond the traditional model of

piriformis syndrome Piriformis syndrome is a condition which is believed to result from nerve compression at the sciatic nerve by the piriformis muscle. It is a specific case of deep gluteal syndrome. The largest and most bulky nerve in the human body is the s ...

. Where sciatic nerve irritation in the buttocks was once thought of as only piriformis muscle, it is now recognized that there are many other causes. Symptoms are pain or dysthesias (abnormal sensation) in the buttocks, hip, and posterior thigh with or without radiating leg pain. Patients often report pain when sitting. The two most common causes are piriformis syndrome and fibrovascular bands (scar tissue), but many other causes exist. Diagnosis is usually done through physical examination,

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

magnetic resonance neurography Magnetic resonance neurography (MRN) is the direct imaging of nerves in the body by optimizing selectivity for unique MRI water properties of nerves. It is a modification of magnetic resonance imaging. This technique yields a detailed image of a n ...

, and diagnostic

nerve block Nerve block or regional nerve blockade is any deliberate interruption of signals traveling along a nerve, often for the purpose of pain relief. #Local anesthetic nerve block, Local anesthetic nerve block (sometimes referred to as simply "nerve b ...

s. Surgical treatment is an endoscopic sciatic

nerve decompression A nerve decompression is a neurosurgical procedure to relieve chronic, direct pressure on a nerve to treat nerve entrapment, a pain syndrome characterized by severe chronic pain and muscle weakness. In this way a nerve decompression targets the ...

where tissue around the sciatic nerve is removed to relieve pressure.

Gluteal space definition

The gluteal space is defined by anatomic landmarks. A simple way to think of the boundaries is the buttocks, or the tissue anterior to the whole of the gluteus maximus muscle. The specific boundaries (top, bottom, left, right, front, back) are defined as * Posterior (back): the

gluteus maximus The gluteus maximus is the main extensor muscle of the hip in humans. It is the largest and outermost of the three gluteal muscles and makes up a large part of the shape and appearance of each side of the hips. It is the single largest muscle in ...

* Anterior (front): posterior acetabular column +

hip joint In vertebrate anatomy, the hip, or coxaLatin ''coxa'' was used by Celsus in the sense "hip", but by Pliny the Elder in the sense "hip bone" (Diab, p 77) (: ''coxae'') in medical terminology, refers to either an anatomical region or a joint o ...

capsule + proximal

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

* Lateral (side further from center):

gluteal tuberosity The gluteal tuberosity is the lateral one of the three upward prolongations of the linea aspera of the femur, extending to the base of the greater trochanter. It serves as the principal insertion site for the gluteus maximus muscle. Structure ...

+ lip of

linea aspera The linea aspera () is a ridge of roughened surface on the posterior surface of the shaft of the femur. It is the site of attachments of muscles and the intermuscular septum. Its margins diverge above and below. The linea aspera is a prominent ...

* Medial (side closer to center):

sacrotuberous ligament The sacrotuberous ligament (great or posterior sacrosciatic ligament) is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends. Structure It runs from the sacrum (the lowe ...

* Superior (top): inferior margin of the

greater sciatic notch The greater sciatic notch is a notch in the ilium, one of the bones that make up the human pelvis. It lies between the posterior inferior iliac spine (above), and the ischial spine (below). The sacrospinous ligament changes this notch into an ope ...

* Inferior (bottom): proximal origin of

hamstring A hamstring () is any one of the three posterior thigh muscles in human anatomy between the hip and the knee: from medial to lateral, the semimembranosus, semitendinosus and biceps femoris. Etymology The word " ham" is derived from the Old ...

s at the

ischial tuberosity The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large posterior bony protuberance on the superior ramus of the ischium. It ...

Anatomy

The hip has five external rotators: The

piriformis The piriformis muscle () is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group. The piriformis muscle has its origin upon the front surface of the sacrum, and in ...

superior gemellus The gemelli muscles are the inferior gemellus muscle and the superior gemellus muscle, two small accessory fasciculi to the tendon of the internal obturator muscle. The gemelli muscles belong to the lateral rotator group of six muscles of the hip ...

obturator internus The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis (bone), pubis. It exits the pelvis, pelvic cavity through the lesser sc ...

inferior gemellus The gemelli muscles are the inferior gemellus muscle and the superior gemellus muscle, two small accessory fasciculi to the tendon of the internal obturator muscle. The gemelli muscles belong to the lateral rotator group of six muscles of the hip ...

, and

quadratus femoris The quadratus femoris is a flat, quadrilateral skeletal muscle. Located on the posterior side of the hip joint, it is a strong external rotator and adductor of the thigh, but also acts to stabilize the femoral head in the acetabulum. The quad ...

. (External rotation is an anatomical term of motion to describe rotation away from the center of the body.) The

inferior gluteal nerve The inferior gluteal nerve is the main motor neuron that innervates the gluteus maximus muscle. It is responsible for the movement of the gluteus maximus in activities requiring the hip to extend the thigh, such as climbing stairs. Injury to this ...

/artery,

pudendal nerve The pudendal nerve is the main nerve of the perineum. It is a Mixed nerve, mixed (motor and sensory) nerve and also conveys Sympathetic nervous system, sympathetic Autonomic nervous system, autonomic fibers. It carries sensation from the exter ...

posterior femoral cutaneous nerve The posterior cutaneous nerve of the thigh (also called the posterior femoral cutaneous nerve) is a sensory nerve of the thigh. It is a branch of the sacral plexus. It supplies the skin of the posterior surface of the thigh, leg, buttock, and als ...

obturator internus nerve The nerve to obturator internus (also known as the obturator internus nerve) is a mixed (sensory and motor) nerve providing motor innervation to the obturator internus muscle and gemellus superior muscle, and sensory innervation to the hip join ...

, superior gemellus nerve, quadratus femoris nerve, and inferior gemellus nerves exit the

greater sciatic foramen The greater sciatic foramen is an opening (:wikt:foramen, foramen) in the posterior human pelvis. It is formed by the sacrotuberous ligament, sacrotuberous and sacrospinous ligaments. The piriformis muscle passes through the foramen and occupies ...

underneath the piriformis. While any of the nerves which exist in this deep gluteal space can be entrapped by deep gluteal space problems, the existing definition of the syndrome tends to focus on sciatic nerve pathology specifically.

Signs and symptoms

As deep gluteal syndrome is defined as entrapment of the sciatic nerve, patients will have pain along the distribution of the nerve, also known as

. These general sciatica symptoms include unilateral, though sometimes bilateral, radiating pain or dysthesias in the affected legs. There may also be abnormal reflexes or

weakness Weakness is a symptom of many different medical conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, ...

of the affected leg. However, significant localized neurological symptoms like

foot drop Foot drop is a gait abnormality in which the dropping of the forefoot happens out of weakness, irritation or damage to the deep fibular nerve (deep peroneal), including the sciatic nerve, or paralysis of the muscles in the anterior portion of th ...

are not typical. Patients also frequently report persistent or intermittent pain or dysthesias in posterior hip, buttocks, or thigh. Unlike discogenic sciatica (caused by the spine), patients with deep gluteal syndrome report exacerbation of symptoms with pressure in the buttocks, such as tenderness or pain on deep palpation, or pain on prolonged sitting. Often patients will be unable to sit more than 20–30 minutes. When patients sit for long periods of time, they may exhibit the antalgic position, where weight is shifted to avoid pressure on the affected side in the hopes of reducing pain. Pain is often increased by activities or positions involving hip flexion on the affected side. Patients with deep gluteal syndrome may have a history of trauma, such as a fall on the buttocks.

Causes

Fibrous bands

Fibrovascular entrapment of the sciatic nerve

Fibrous bands are the most common cause of deep gluteal syndrome, and are frequently observed intraoperatively during endoscopic sciatic nerve explorations. Fibrous tissue, also known as

scar tissue "Scar Tissue" is the first single from American rock band Red Hot Chili Peppers' seventh studio album, ''Californication'' (1999). Released on May 25, 1999, the song spent a then-record 16 consecutive weeks atop the US ''Billboard'' Hot Modern R ...

, is dense, inelastic tissue that can form after the body heals from an injury. Fibrous bands are fibrous tissue with a long, thin shape like a rope or a band. It's often not clear how internal scarring would materialize. However, many deep gluteal syndrome patients do have a history of falls or trauma in the gluteal space. Fibrous bands can be compressive / bridge-type bands, adhesive / horse-strap bands, or have an undefined distribution. The bridge-type bands act as a barrier preventing the sciatic nerve from moving past a given point with compression, like a seat belt. The adhesive bands strongly anchor the nerve and completely limit movement beyond a certain point with traction, like a leash. Fibrous bands with an undefined distribution anchor the sciatic nerve in multiple directions, like glue.

Piriformis syndrome

Piriformis syndrome is the second most common cause of deep gluteal syndrome, and the most commonly involved among the various musculotendinous structures in the pelvis. There are several mechanisms proposed where the piriformis entraps the sciatic nerve:

hypertrophy Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It is distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number. Although hypertro ...

(muscle size squeezes tissue around it), dynamic nerve entrapment at the muscle (muscle pinches the nerve with certain movements), anomalous course of the nerve, anomalous attachments of the muscle,

iatrogenic Iatrogenesis is the causation of a disease, a harmful complication, or other ill effect by any medical activity, including diagnosis, intervention, error, or negligence." Iatrogenic", ''Merriam-Webster.com'', Merriam-Webster, Inc., accessed 27 ...

injury, and trauma. Anatomic variations of sciatic nerve branching were speculated to play a role, however this is unproven, as surgery groups for deep gluteal syndrome tend to have the same prevalence of sciatic nerve branching anomalies found in non-patient cadavers.

Other causes

There are many other causes of deep gluteal syndrome although less frequent. They include

conditions, gluteal muscles, gemelli-obturator internus syndrome, vascular abnormalities (e.g. dilated veins), quadratus femoris/ischiofemoral impingement, space-occupying lesions (

neuroma A neuroma (; plural: neuromata or neuromas) is a growth or tumor of nerve tissue. Neuromas tend to be benign (i.e. not cancerous); many nerve tumors, including those that are commonly malignant, are nowadays referred to by other terms. Neuromas ...

ganglion cyst A ganglion cyst is a fluid-filled bump associated with a joint or tendon sheath. It most often occurs at the back of the wrist, followed by the front of the wrist. The cause is unknown. The underlying mechanism is believed to involve an out ...

fibrosis Fibrosis, also known as fibrotic scarring, is the development of fibrous connective tissue in response to an injury. Fibrosis can be a normal connective tissue deposition or excessive tissue deposition caused by a disease. Repeated injuries, ch ...

after classic open surgery of piriformis, trauma, and orthopedic causes. Sometimes rare, pathological anatomic variations may be the cause, such as a muscle fiber piercing a nerve.

Pathophysiology

The sciatic nerve is highly mobile in the deep gluteal space with hip and even knee movements. For example, hip

flexion Motion, the process of movement, is described using specific anatomical terminology, anatomical terms. Motion includes movement of Organ (anatomy), organs, joints, Limb (anatomy), limbs, and specific sections of the body. The terminology used de ...

with knee

extension Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (proof theory) * Extension (predicate logic), the set of tuples of values that ...

(also called a straight leg raise) causes the sciatic nerve in the deep gluteal space to move 28mm towards the center of the body. Hip movements may also create dynamic impingement between muscles. For example, hip flexion,

adduction Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

, and

internal rotation Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

stretch the piriformis muscle and reduce the space between the

and

as well as the piriformis and

. Normally the sciatic nerve can stretch, glide, and accommodate moderate compression associated with normal hip joint and knee movements, but it may be impeded by various pathologies. Diminished or absent sciatic nerve mobility is believed to be the precipitating cause of sciatic neuropathy in deep gluteal syndrome. This impaired mobility induces strain and compression on the sciatic nerve during various hip movements. Even a 6% stretch on a nerve can result in impaired conduction.

Diagnosis

The general workup involves excluding lumbar, pelvic, and hip pathologies, physical examination,

(MRN) imaging, and diagnostic injections. The use of MRN and diagnostic injections are relatively new diagnostic tools that allow making precise diagnoses where standard diagnostic modalities has failed. Nerve testing such as EMG and NCS can be done but there is little evidence it's helpful.

Differential diagnoses In healthcare, a differential diagnosis (DDx) is a method of analysis that distinguishes a particular disease or condition from others that present with similar clinical features. Differential diagnostic procedures are used by clinicians to dia ...

(different conditions with similar symptoms) include

pudendal nerve entrapment Pudendal nerve entrapment is an uncommon, chronic pelvic pain condition in which the pudendal nerve (located in the pelvis) is entrapped and compressed. There are several different anatomic locations of potential entrapment (see Anatomy). Pudendal ...

, ischiofemoral impingement, greater trochanter ischial impingement, and ischial tunnel syndrome.

Exclude hip/spine/pelvis pathologies early

Diagnosing deep gluteal syndrome is often is a clinical challenge because the symptoms can have considerable overlap with symptoms of pelvic, hip, and spine pathology. In particular lumbar pathology should be excluded early as

that originates in the spine is thought to be more common than sciatica that originates in the deep gluteal space. When assessing the possibility of lumbar pathology,

(MRI) should not be the sole basis for a diagnosis as it has very high sensitivity which may cause non-discogenic sciatic nerve entrapment to be overlooked due to

false positive A false positive is an error in binary classification in which a test result incorrectly indicates the presence of a condition (such as a disease when the disease is not present), while a false negative is the opposite error, where the test resu ...

diagnosis. On MRI, disc lesions are present in many asymptomatic people. Intrapelvic problems should be excluded by covering a

gynecologic Gynaecology or gynecology (see American and British English spelling differences) is the area of medicine concerned with conditions affecting the female reproductive system. It is often paired with the field of obstetrics, which focuses on pre ...

urologic Urology (from Greek οὖρον ''ouron'' "urine" and ''-logia'' "study of"), also known as genitourinary surgery, is the branch of medicine that focuses on surgical and medical diseases of the urinary system and the reproductive organs. Org ...

history. High resolution imaging can also rule out some forms of intrapelvic problems such as

endometriosis Endometriosis is a disease in which Tissue (biology), tissue similar to the endometrium, the lining of the uterus, grows in other places in the body, outside the uterus. It occurs in women and a limited number of other female mammals. Endomet ...

or vascular abnormalities.

Physical examination

The clinical signs should determine the diagnostic approach. For example, sitting pain is associated with sciatic nerve entrapment under the piriformis, but pain lateral to the

ischium The ischium (; : is ...

when walking is associated with ischiofemoral impingement. The core of the physical examination is

palpation Palpation is the process of using one's hands to check the body, especially while perceiving/diagnosing a disease or illness. Usually performed by a health care practitioner, it is the process of feeling an object in or on the body to determine ...

and stretch/activation tests of the external hip rotators. As patients often have tenderness in the buttocks, palpation can provide information on which structures may be involved. For example, tenderness over the gluteal muscle at the

may be

; lateral to the

may be ischiofemoral impingement; medial to the ischial tuberosity may be pudendal nerve entrapment. Stretch/activation tests of the external hip rotators try to create dynamic impingement with hip/knee movements. The most used ones are the FADIR test (

, and

), seated piriformis challenge test, and the active piriformis test. Additional tests include Lasegue test (known as the straight leg raise test), Pace's sign, Freiberg's sign, and the Beatty test.

Imaging

Magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

(MRI) and

(MRN) are the diagnostic procedures of choice for deep gluteal syndrome. MRN provides additional information that MRI alone can't by visualizing structural properties of the

. As an example of the diagnostic improvement of MRN, when MRI is used to assess piriformis muscle asymmetry, it has 46% sensitivity and 66% specificity for piriformis syndrome. When MRN is used and includes unilateral sciatic nerve hyperintensity at the sciatic notch, the sensitivity increases to 64% and the specificity increases to 93%. MRN's advantage is in identifying anatomic nerve abnormalities by visualizing neural structures such as nerve

diameter In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...

, nerve fascial

edema Edema (American English), also spelled oedema (British English), and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue (biology), tissue. Most commonly, the legs or arms are affected. S ...

, fascicular appearance, perifascicular and endoneural signal intensity.

Diffusion tensor imaging Diffusion-weighted magnetic resonance imaging (DWI or DW-MRI) is the use of specific MRI sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in MR images. It ...

/ Magnetic resonance tractography is expected to be another powerful clinical tool for diagnosis of deep gluteal syndrome because it can reveal additional physiological information about the nerves, but is still in the research phase.

Diagnostic injections

Image-guided perineural injections of the sciatic nerve are

s with

anesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into t ...

and

steroids A steroid is an organic compound with four fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter mem ...

, and they have both diagnostic and therapeutic function. The blocks are used to localize the source of pain when palpation of internal structures is not possible. The image-guidance is to increase accuracy of the needle placement and visualize the spread of the injected material.

Ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

-guided injections are the gold standard for differentiating deep gluteal syndrome from other sources of pain. Diagnostic injections function in a similar way to deep palpation. While palpation causes a signal to be sent along a nerve which patients can localize relative to their pain (the spot hurts or it doesn't), anesthetics will block signals sent along nerves. Successful blocks are expected to lead to immediate and complete or near-complete pain relief while unsuccessful blocks are expected to have no improvement in pain. The anesthetics used in nerve blocks are typically a mix of

lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...

and

bupivicaine Bupivacaine, marketed under the brand name Marcaine among others, is a medication used to decrease sensation in a specific small area. In nerve blocks, it is injected around a nerve that supplies the area, or into the spinal canal's epidural ...

, and the numbness will last for 4–6 hours. Nerve blocks can distinguish between different types of nerve lesions as well as distinguish between sciatic and spinal pathology. Blocks can be repeated on the same area or different areas to increase confidence in the diagnosis (e.g. to rule in the suspected diagnosis and rule out differential diagnoses).

Treatment

The indications for conservative therapy or surgery are not well defined due to a paucity of controlled trials. If patients do not have clear indications for surgery then a gradual approach is recommended where more conservative treatments are tried before more invasive treatments. Despite the recommendation to start with conservative therapy, it fails in as many half of patients with deep gluteal syndrome. In some cases surgery may be immediately indicated, such as imaging finding a mass lesion compressing the sciatic nerve.

Conservative therapy

The main approaches to conservative treatment of deep gluteal syndrome are rest, activity modification,

physical therapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

for 6+ weeks, analgesic / anti-inflammatory drugs, and injections. Conservative therapy fails in as many half of patients with deep gluteal syndrome. The purpose of physical therapy is to restore normal hip and spine biomechanics. This is done by strengthening and stretching the involved muscles (external hip rotators) as well as sciatic nerve glides. There should also be an emphasis on core stabilization (muscles involved in posture, balance, and overall body strength) and flexibility. Compressive, tensile, shearing, and rotatory forces are present during normal movements, and abnormal biomechanics can lead to a pathological distribution of forces leading to stress injuries and scarring of soft tissue. Abnormal biomechanics such as a posterior pelvic tilt can also change the distribution of pressure when sitting both externally and internally. If left untreated, poor biomechanics potentially also lead to compensatory injuries. Injections are also a first-line therapy.

Local anesthetics A local anesthetic (LA) is a medication that causes absence of all sense, sensation (including pain) in a specific body part without loss of consciousness, providing local anesthesia, as opposed to a general anesthetic, which eliminates all sen ...

corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invol ...

, and

Botulinum toxin Botulinum toxin, or botulinum neurotoxin (commonly called botox), is a neurotoxic protein produced by the bacterium ''Clostridium botulinum'' and related species. It prevents the release of the neurotransmitter acetylcholine from axon en ...

(botox) are frequently used in conditions like

. Ultrasound-guidance is a popular choice for injections, but injections can also be done under CT or MRI-guidance. Controlled studies have found that for patients with suspected piriformis syndrome, botox injections into the piriformis are more effective than a

placebo A placebo ( ) can be roughly defined as a sham medical treatment. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. Placebos are used in randomized clinical trials ...

and also more effective than just an anesthetic block alone. The duration of anesthetics is in hours and consequently the anesthetic alone doesn't lead to long-lasting relief. Corticosteroids are often used for its anti-inflammatory effects which can help when nerves are sensitized due to a nearby local inflammation as well as reducing pressure on a nerve from swelling. The duration of steroid injections is unclear but studies on knee osteoarthritis have reported effects lasting at least 1 week and up to 3 months. Botox will paralyze a muscle which can be helpful for chronic

muscle spasms A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ, such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a musc ...

causing dynamic entrapment, or

placing pressure on a nerve. Botox will last for about 3 months.

Surgery

Surgery involves a

with or without muscle resection. The surgery can be performed with external incisions (open surgery) or endoscopically.

Endoscopy An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...

allows for complete

visualization and access for decompression in the extrapelvic gluteal space. The goal of surgery is to restore normal nerve kinematics and nerve conduction. During surgery this is measured by

nerve conduction studies A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called ...

and

electromyography Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyo ...

, as well as observing the sciatic nerve mobility while the patients hips are moved. This testing can be done before and after the decompression to verify improvement before concluding the surgery. The outcomes measures include modified hip harris score (mHHS), VAS score (numerical pain scores), and Benson outcomes questionnaire. At a 2 year follow up, 80% of patients demonstrated good-to-excellent Benson ratings postoperatively. In one study assessing 122 patients, for pain assessments, 90% improved, 8% had no change, and 2% were worse. For strength assessments, it's 86% improved, 9% saw no change, and 5% were worse. If patients had numbness, then 59% saw improvement and 41% did not see improvement. VAS score changes are consistently positive, with an average of 6.7 preoperative (moderate-severe pain) to 2.1 postoperative (mild pain). The endoscopic approach has low complication rate (0% major and 1% minor). Open surgery has higher complication rate (1% major and 8% minor). Major complications are potentially life-threatening and require immediate as well as intensive medical interventions, while minor complications are not life-threatening and can be managed with less aggressive treatment.

Epidemology

There's little epidemiological data on deep gluteal syndrome. The main epidemiological data available is on

. Due to challenges in defining and diagnosing piriformis syndrome, attempts at quantifying its prevalence have led to conflicting estimates. Recent estimates for the prevalence of piriformis syndrome are 6% and 17% of all patients with low back pain / sciatica. However, this may be an underestimate due to the high sensitivity of MRI to identify lumbar pathologies (leading to incorrect discogenic diagnoses), the lower referral rate of deep gluteal syndrome patients to neurosurgeons and orthopedic spine specialists (leading to missed diagnoses), and the frequent failure to recognize the diagnosis.

History

The understanding of

has evolved. Discogenic causes (coming from the spine) were first recognized. Later,

was proposed as a cause of non-discogenic sciatic

nerve entrapment Nerve compression syndrome, or compression neuropathy, or nerve entrapment syndrome, is a medical condition caused by chronic, direct pressure on a peripheral nerve. It is known colloquially as a ''trapped nerve'', though this may also refer to n ...

. However, piriformis syndrome remained controversial for many years as a distinct pathophysiological entity because there was no objective diagnostic criteria, no reliable treatment, and no reasonable pathophysiology to support its existence. Over time accurate diagnosis, treatment, and pathophysiology were improved upon. This improved understanding of posterior hip anatomy and nerve kinematics helped to identify other locations the

might be entrapped. The eventual development of

endoscopic An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...

surgical techniques to explore the sciatic nerve radically changed the understanding of non-discogenic sciatic nerve entrapment. It supported further classification because many other causes were found that did not fit into the traditional model of piriformis syndrome. In particular, the concept of fibrous bands (scar tissue) restricting sciatic nerve mobility and causing entrapment was a radical change in the diagnosis and therapeutic approach to non-discogenic sciatica. The all encompassing term "deep gluteal syndrome" was developed to appreciate the many causes of non-discogenic sciatic nerve entrapment in the deep gluteal space. Piriformis syndrome is now considered one of many causes of deep gluteal syndrome. * 1947 - Piriformis syndrome described. * 1999 - Deep gluteal syndrome is proposed to replace piriformis syndrome. * 2003 - Endoscopic surgery to release the piriformis muscle in the deep gluteal space. * 2005 - Large study of the diagnosis and treatment of patients with non-discogenic sciatica.

Magnetic resonance neurography Magnetic resonance neurography (MRN) is the direct imaging of nerves in the body by optimizing selectivity for unique MRI water properties of nerves. It is a modification of magnetic resonance imaging. This technique yields a detailed image of a n ...

and image-guided

s are used to diagnose at least 80% of patients for which standard diagnostic modalities had failed. The various causes of non-discogenic sciatic nerve entrapment are categorized. * 2011 - Endoscopic surgery to decompress the sciatic nerve in the deep gluteal space. * 2015 - Definition, diagnosis, treatment, etc. proposed for deep gluteal syndrome.

Society and culture

Patients often face challenges when trying to find accurate diagnosis and surgical treatment for deep gluteal syndrome. Pathologies of the pelvic nerves have historically rarely been seriously explored clinically, even though hundreds of thousands of people with sciatica each year have absent lumbar

disc herniation A disc herniation or spinal disc herniation is an injury to the intervertebral disc between two vertebrae, usually caused by excessive strain or trauma to the spine. It may result in back pain, pain or sensation in different parts of the body, ...

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

. Difficult access to the nerves has made clinical assessment, and surgical treatment historically impractical. Unreliable imaging of nerves on standard MRI have made it difficult to establish diagnoses. Consequently, the standard treatment regimen has been to treat symptomatically when no cause is found. However, patients with deep gluteal syndrome can report high VAS scores (6.7 +/-2) characteristic of moderate (>3) and severe pain (>7.5), and may not find sufficient relief in conservative or symptomatic treatment. If patients don't respond to non-opioid therapy, physician reluctance to prescribe opioids for chronic non-malignant pain can leave patients with severe uncontrolled pain that can profoundly impact quality of life. There is unclear ownership among medical specialties for many entrapment neuropathies which adds additional challenges for patients. For example, entrapment neuropathies require a detailed understanding of neurology and neuropathology, but these specialties are paradoxically rarely involved, especially for the pelvic nerves. Instead, patients with entrapment of the pelvic nerves may see specialists who treat related body parts such as those from

urology Urology (from Ancient Greek, Greek wikt:οὖρον, οὖρον ''ouron'' "urine" and ''wiktionary:-logia, -logia'' "study of"), also known as genitourinary surgery, is the branch of medicine that focuses on surgical and medical diseases of t ...

gynaecology Gynaecology or gynecology (see American and British English spelling differences) is the area of medicine concerned with conditions affecting the female reproductive system. It is often paired with the field of obstetrics, which focuses on pre ...

physiatry Physical medicine and rehabilitation (PM&R), also known as physiatry, and outside the United States as physical and rehabilitation medicine (PRM), is a branch of medicine that aims to enhance and restore functional ability and quality of life ...

, medical and surgical

gastroenterology Gastroenterology (from the Greek gastḗr- "belly", -énteron "intestine", and -logía "study of") is the branch of medicine focused on the digestive system and its disorders. The digestive system consists of the gastrointestinal tract, sometime ...

, and

orthopaedic surgery Orthopedic surgery or orthopedics (American and British English spelling differences, alternative spelling orthopaedics) is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgic ...

who themselves are hampered by deficient knowledge of nerves and diagnostic tools (

and image-guided

s). The list of specialties that patients may see for sciatic nerve entrapment also includes

neurologists Neurology (from , "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the nervous system, which comprises the brain, the s ...

(nerves),

neurosurgeons Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system including the brain, ...

(nerve surgery), spine surgeons (

radiculopathy Radiculopathy (; ), also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly (a neuropathy). Radiculopathy can result in pain (radicular pain), weakness, altered se ...

), interventional radiologists (injections), and anesthesiologists (

pain management Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute (medicine), acute and simple to chronic condition, chronic and challenging. Most physici ...

). The lack of clear ownership in treatment can result in patients consulting multiple specialists before finding one with the expertise to address their condition, if they are able to find such a specialist at all. One study author noted that, on average, his patients who were successfully treated for piriformis syndrome saw a mean of 8.5 specialist physicians for their sciatica before his diagnosis was proposed.

References

{{Reflist Syndromes