Deep Gluteal Syndrome Due to Piriformis Injury

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Deep Gluteal Syndrome Caused by Piriformis Injury

Posterior hip, buttock, and leg pain are common complaints in clinical practice and are typically related to diagnoses such as Radiculopathy, Sciatica, or Piriformis Syndrome. Although non-discogenic sciatic nerve irritation has historically been attributed to the anatomic relationship between the piriformis muscle and the sciatic nerve, further investigations have shown that other structures can be involved in sciatic nerve entrapment within the gluteal space. This has led to the recognition that there could be other pain syndromes occurring in the same region, causing non-discogenic sciatic nerve irritation. These are collectively referred to as Deep Gluteal Syndrome. Structures that can be involved in sciatic nerve entrapment within the deep gluteal space include:

• Piriformis Muscle: Hypertonicity or anatomical variations of the piriformis muscle may lead to sciatic nerve compression as it passes beneath or through the muscle (referred to as Piriformis Syndrome).
• Gemelli-Obturator Internus Complex: The sciatic nerve passes under the belly of the piriformis and over the superior gemelli-obturator internus muscles. It is proposed that the contraction of these muscles may produce a scissor-like effect, resulting in dynamic compression of the nerve (referred to as Gemelli-Obturator Internus Syndrome). 
• Hamstring Muscles: Hamstring tendon thickening or partial avulsion can lead to sciatic nerve entrapment (referred to as Hamstring Syndrome or Ischial Tunnel Syndrome).
  
• Fibrous Bands: The sciatic nerve may also be compressed or entrapped by fibrous bands, scar tissue, or abnormal anatomy in the deep gluteal region.
• Ischiofemoral Impingement: This occurs when the space between the ischium bone and the femur is reduced due to anatomical variations such as a prominent ischial tuberosity or abnormal morphology of the quadratus femoris muscle, causing impingement and compression of structures within the deep gluteal region (referred to as Ischiofemoral Impingement Syndrome).
• Space-Occupying Lesions: The sciatic nerve can be compressed or entrapped by the presence of space-occupying lesions.

Deep Gluteal Syndrome is a preferred name to describe the presence of pain in the buttock and leg caused by non-discogenic entrapment of the sciatic nerve. It is important to consider the possibility of Deep Gluteal Syndrome as a diagnosis for the patient’s complaint to avoid an incorrect diagnosis of lumbar disc herniation, leading to unnecessary spinal surgery.

The symptoms of Deep Gluteal Syndrome can vary but they commonly include pain in the buttock, posterior hip, or posterior thigh, which may radiate down the leg. Other symptoms may include numbness, tingling, or weakness in the affected leg, as well as pain when sitting or performing activities that involve hip movement.

A diagnosis of Deep Gluteal Syndrome requires a thorough clinical history, physical examination, and imaging studies such as MRI or ultrasound to assess the structures in the deep gluteal region. Electromyography (EMG) or nerve conduction studies may also be used to evaluate nerve function and identify nerve entrapment.

The material in this study unit focuses on the involvement of the piriformis muscle as the cause of Deep Gluteal Syndrome.

Piriformis Syndrome

Piriformis Syndrome can be classified as a subgroup of Deep Gluteal Syndrome. Piriformis Syndrome is a condition characterized by pain and discomfort in the buttock, often radiating down the back of the leg. Piriformis Syndrome is a somewhat controversial diagnosis. Opinions vary from those who say that the condition is extremely rare, to those who claim it is a relatively common disorder that is often overlooked.

Piriformis Syndrome is typically defined as hypertonicity or anatomical variations of the piriformis muscle, leading to sciatic nerve compression as it passes beneath or through the muscle. Anatomical variation in the relationship of the sciatic nerve to the piriformis muscle is often cited as a necessary prerequisite to developing the condition. The sciatic nerve most commonly exits beneath the muscle, but in certain individuals, the nerve or a portion of it passes through or above the muscle. Some research suggests that these anomalous arrangements occur just as frequently in asymptomatic individuals as in those diagnosed with Piriformis Syndrome, suggesting that anomalous anatomical arrangement is not a precursor to the condition.

Mechanisms proposed to explain the etiology of Piriformis Syndrome include:

• Injuries causing piriformis spasm, inflammation, or swelling
• Repetitious activity leading to an overload of the piriformis muscle
• Haematoma formation following trauma to the piriformis muscle
• Sustained external pressure over the piriformis muscle (e.g., prolonged sitting)
• Sacroiliac dysfunction

• Buttock or posterior hip pain which may extend down the back of the leg
• Sciatica-like symptoms
• Pain aggravation by prolonged sitting and physical activity that involves hip movement (e.g., walking)
• Pain that may disturb the patient’s sleep

• Localized buttock pain when pressure is applied over the piriformis muscle and sciatic trunk. This may aggravate or reproduce the patient’s pain and paresthesia in the posterior leg.
• The Active Piriformis test, Seated Piriformis Stretch test, Freiberg test, the Pace Manoeuvre, and the Beatty Manoeuvre are likely to be positive.
• Sciatic nerve tension tests may be positive.

• MRI is regarded as the imaging modality of choice for diagnosing various causes of Deep Gluteal Syndrome. MRI may reveal piriformis enlargement, anatomical variations, or localized edema of both the muscle and the sciatic nerve. In addition, these imaging technologies help to rule out serious pathology.
• Plain radiography may exclude osseous pathology, but it is usually of limited value for the diagnosis of Deep Gluteal Syndrome.

The following are examples of red flags for patients presenting with buttock pain:

• Severe pain
• Unrelenting pain
• Nocturnal pain
• Significant loss of range of motion
• Significant neurological impairment
• Trauma
• Deformity
• Loss of bladder/bowel control
• Severe tenderness on palpation or severe pain with any examination procedure

If any red flags are identified during history taking and clinical examination, referral for urgent medical evaluation and further investigation is warranted.

Myofascial Pain Syndrome Causing Buttock and Leg Pain

In patients presenting with buttock and leg pain, a complete clinical examination should include an evaluation of the following muscles to assess the presence of myofascial trigger points as the concomitant or primary causes of the patient’s pain:

• Gluteus medius
• Piriformis
• Gluteus minimus

Trigger points may be located anywhere within a muscle and its fascia. Therefore, the entire muscle should be examined thoroughly. However, based on our clinical experience, the common locations for trigger points are presented in the images below.