Hypermobility Spectrum Disorder: Diagnosis, Evaluation, and Differentiation

How is HSD diagnosed?

Diagnosis of Hypermobility Spectrum Disorder (HSD) involves a comprehensive clinical evaluation by a healthcare professional, primarily focusing on a detailed patient history, physical examination, and the exclusion of other conditions, particularly hypermobile Ehlers-Danlos Syndrome (hEDS) and other connective tissue disorders.

Understanding Hypermobility Spectrum Disorder (HSD)

Hypermobility Spectrum Disorder (HSD) is a condition characterized by symptomatic joint hypermobility that does not meet the specific diagnostic criteria for hypermobile Ehlers-Danlos Syndrome (hEDS) or other named connective tissue disorders. While often confused with hEDS due to overlapping symptoms, HSD represents a spectrum of hypermobility-related issues, ranging from localized joint hypermobility to generalized hypermobility affecting multiple joints. An accurate diagnosis is crucial for understanding symptoms, guiding appropriate management strategies, and preventing potential complications.

The Diagnostic Process: A Multifaceted Approach

Diagnosing HSD is a clinical process, meaning there is no single definitive test, such as a blood test or imaging study, that confirms the condition. Instead, diagnosis relies on a thorough assessment by an experienced clinician, often a rheumatologist or geneticist, who specializes in connective tissue disorders. The process involves a careful integration of patient history, physical examination findings, and the systematic exclusion of other conditions that could explain the symptoms.

Initial Clinical Evaluation and History Taking

The diagnostic journey for HSD begins with a detailed clinical evaluation, where the healthcare provider gathers extensive information about the patient's health.

• Patient History: This is a critical component, focusing on:

  • Symptom Onset and Evolution: When did symptoms begin? How have they progressed?
  • Pain: Location, type (e.g., sharp, aching, burning), intensity, duration, and aggravating/alleviating factors. Chronic musculoskeletal pain is a hallmark of symptomatic hypermobility.
  • Fatigue: Presence and severity of debilitating fatigue.
  • Joint Instability: History of subluxations (partial dislocations) or dislocations, joint effusions (swelling), or sensations of joints "giving way."
  • Autonomic Dysfunction: Symptoms such as orthostatic intolerance (POTS-like symptoms), fainting, dizziness, or rapid heart rate.
  • Gastrointestinal Issues: Chronic constipation, diarrhea, reflux, or abdominal pain.
  • Skin and Tissue Manifestations: While less pronounced than in hEDS, subtle signs like soft, velvety skin, easy bruising, or poor wound healing may be noted.
  • Family History: Presence of hypermobility, chronic pain, or diagnosed connective tissue disorders in family members.
  • Co-occurring Conditions: Information on anxiety, depression, mast cell activation syndrome (MCAS), or other conditions commonly associated with hypermobility.

• Physical Examination: A comprehensive physical assessment is performed to evaluate joint range of motion, stability, and overall musculoskeletal integrity. This includes:

  • Observation of posture and gait.
  • Palpation of joints and muscles for tenderness or swelling.
  • Assessment of joint hypermobility across various joints (e.g., fingers, wrists, elbows, shoulders, spine, hips, knees, ankles).

The Beighton Score: A Key Screening Tool

The Beighton Score is a widely used, nine-point system for quantifying generalized joint hypermobility (GJH). It is a rapid and simple clinical tool, but it is important to understand its role: it identifies generalized joint hypermobility, but it is not diagnostic for HSD or hEDS on its own. A higher score indicates greater joint laxity.

The nine points assessed are:

1. Passive dorsiflexion of the 5th metacarpophalangeal joint to 90 degrees or more (bilateral, 1 point per side).
2. Passive apposition of the thumb to the forearm (bilateral, 1 point per side).
3. Elbow hyperextension beyond 10 degrees (bilateral, 1 point per side).
4. Knee hyperextension beyond 10 degrees (bilateral, 1 point per side).
5. Forward flexion of the trunk with palms resting flat on the floor with knees fully extended (1 point).

A score of 4/9 or more (or 5/9 or more depending on age and ethnicity) typically indicates generalized joint hypermobility. However, many individuals with a high Beighton score are asymptomatic, while others with lower scores can still experience significant hypermobility-related symptoms. Therefore, the Beighton score is part of a larger clinical picture.

Beyond the Beighton Score: Comprehensive Assessment

Diagnosing HSD requires going beyond the Beighton score to consider the full clinical presentation.

• Clinical Criteria for HSD: The diagnosis of HSD is made when a patient presents with symptomatic joint hypermobility (localized, historical, or generalized) that causes problems such as chronic pain, instability, or other systemic manifestations, but does not fulfill the diagnostic criteria for hypermobile Ehlers-Danlos Syndrome (hEDS) or other specific connective tissue disorders (e.g., Marfan Syndrome, Loeys-Dietz Syndrome). It's a diagnosis of exclusion and clinical judgment.

• Assessment of Associated Manifestations: Clinicians will also assess for the presence of non-musculoskeletal symptoms that frequently co-occur with hypermobility, even if they are not part of the primary diagnostic criteria for HSD itself. These can include:

  • Chronic widespread pain.
  • Fatigue.
  • Dysautonomia (e.g., Postural Orthostatic Tachycardia Syndrome - POTS).
  • Gastrointestinal dysmotility.
  • Anxiety, panic disorder, or phobias.
  • Pelvic floor dysfunction.
  • Mast cell activation symptoms.

• Exclusion of Other Conditions: A critical step in diagnosing HSD is to rule out other conditions that can cause similar symptoms, especially more severe or specific connective tissue disorders.

  • Differential Diagnosis: This involves considering and systematically excluding conditions like:
    • Hypermobile Ehlers-Danlos Syndrome (hEDS): This is the most important differential diagnosis. HSD is often considered when hEDS criteria are not fully met. The criteria for hEDS are more stringent and require the presence of generalized joint hypermobility, systemic manifestations, and a family history, or a combination of these, without evidence of other connective tissue disorders.
    • Other Ehlers-Danlos Syndromes (e.g., Classical, Vascular, Kyphoscoliotic EDS): These are typically ruled out through genetic testing as they have known genetic mutations.
    • Marfan Syndrome, Loeys-Dietz Syndrome, Stickler Syndrome: These are also genetic connective tissue disorders with specific diagnostic criteria and often unique features (e.g., cardiovascular involvement in Marfan/Loeys-Dietz).
    • Rheumatological Conditions: Inflammatory arthritides or autoimmune diseases that can cause joint pain or laxity.
  • Genetic Testing: While there is no specific genetic test for HSD (and currently none for hEDS), genetic testing may be performed to rule out other specific types of EDS or other genetic connective tissue disorders that have known causative genes. This helps ensure an accurate diagnosis and appropriate management.

Who Diagnoses HSD?

Due to the complex nature of HSD and its overlap with other conditions, diagnosis is typically made by specialists.

• Rheumatologists: Often the primary specialists involved, given their expertise in musculoskeletal and connective tissue disorders.
• Clinical Geneticists: Especially important when considering or ruling out other inherited connective tissue disorders.
• Orthopedists: May be involved in managing specific joint issues but usually refer for diagnostic clarification if hypermobility is suspected as a systemic issue.
• Physical Therapists: While not able to formally diagnose, they play a crucial role in identifying hypermobility, assessing its impact, and contributing to the overall clinical picture that aids the diagnosing physician.

A multidisciplinary approach, involving various specialists, is often beneficial for comprehensive assessment and management.

The Importance of an Accurate Diagnosis

Receiving an accurate diagnosis of HSD is profoundly impactful for individuals. It provides:

• Validation: Legitimizes the often chronic and debilitating symptoms that may have been previously dismissed or misunderstood.
• Guidance for Management: Leads to targeted and appropriate treatment strategies, including specialized physical therapy focused on strengthening and proprioception, pain management, and addressing associated systemic symptoms.
• Prevention: Helps prevent inappropriate interventions or unnecessary surgeries by understanding the underlying tissue fragility.
• Education: Empowers individuals to understand their body, manage their condition, and make informed lifestyle choices.

Living with HSD: Post-Diagnosis

Once diagnosed, the focus shifts to management, which is highly individualized. It typically involves a combination of strength training (emphasizing stability over flexibility), proprioceptive exercises, pain management techniques, lifestyle adjustments, and addressing co-occurring conditions. Education about the condition is paramount, enabling individuals to become active participants in their own care.