Hypermobility Spectrum Disorder (HSD): Understanding, Symptoms, Diagnosis, and Management

What is HSD in medical terms?

Hypermobility Spectrum Disorder (HSD) is a medical diagnosis for individuals experiencing symptomatic joint hypermobility that does not meet the diagnostic criteria for other more specific connective tissue disorders, most notably hypermobile Ehlers-Danlos Syndrome (hEDS).

Understanding Hypermobility Spectrum Disorder (HSD)

Joint hypermobility refers to the ability of a joint to move beyond its normal range of motion. While some individuals may have hypermobile joints without experiencing any symptoms (asymptomatic joint hypermobility), others may develop a range of debilitating symptoms, primarily musculoskeletal pain, fatigue, and recurrent injuries. HSD is the diagnostic term used when symptomatic joint hypermobility is present, but the individual does not fully meet the more stringent diagnostic criteria for a specific Ehlers-Danlos Syndrome (EDS) subtype or another defined connective tissue disorder.

The concept of HSD was introduced by the International Consortium on EDS and HSD in 2017 to provide a more precise and comprehensive classification system for individuals with symptomatic hypermobility. It replaced older, less specific terms like Benign Joint Hypermobility Syndrome (BJHS) or Joint Hypermobility Syndrome (JHS), acknowledging that hypermobility exists on a spectrum of severity and impact.

Key Characteristics and Symptoms

The manifestations of HSD are highly variable and can affect multiple body systems, not just the joints. Common symptoms and associated conditions include:

• Musculoskeletal Pain: This is often the most prominent symptom, presenting as widespread chronic pain (arthralgia, myalgia), joint instability, and frequent sprains or subluxations (partial dislocations). Pain can be neuropathic, nociceptive, or nociplastic.
• Fatigue: Profound, often disabling fatigue is common, not always alleviated by rest.
• Proprioceptive Dysfunction: Impaired body awareness and coordination, leading to clumsiness, falls, and difficulty with balance.
• Autonomic Dysfunction: Conditions such as Postural Orthostatic Tachycardia Syndrome (POTS), characterized by dizziness, lightheadedness, palpitations, and fainting upon standing.
• Gastrointestinal Issues: Dysmotility (slow digestion), irritable bowel syndrome (IBS)-like symptoms, and acid reflux.
• Skin Manifestations: While typically less severe than in classic EDS, skin may be soft, velvety, or stretchy, and bruising may occur easily.
• Pelvic Floor Dysfunction: Incontinence, pelvic pain, or prolapse.
• Anxiety and Depression: Higher rates of anxiety disorders, panic attacks, and depression are observed, potentially due to chronic pain, fatigue, and the systemic impact of the condition.
• Headaches: Including migraines and cervicogenic headaches.
• Mast Cell Activation Syndrome (MCAS): A condition where mast cells inappropriately release inflammatory mediators, leading to allergic-like symptoms.

Etiology: What Causes HSD?

HSD is primarily considered to have a genetic basis, involving alterations in the connective tissue that provides structure and support to the body. While specific gene mutations are not yet identified for HSD as they are for some EDS types, it is understood to involve variations in genes that encode for collagen and other proteins crucial for connective tissue integrity. This leads to laxity in ligaments, tendons, and joint capsules. The exact inheritance pattern can vary, but it often appears to run in families.

Diagnosis of HSD

The diagnosis of HSD is primarily clinical, meaning it is based on a thorough medical history, physical examination, and the exclusion of other conditions. There is no specific blood test or imaging study that can definitively diagnose HSD.

• Clinical Assessment: A healthcare provider will assess the extent of joint hypermobility using standardized tools like the Beighton Score, which evaluates hypermobility in nine specific joints. However, a high Beighton score alone does not confirm HSD; it only indicates generalized joint hypermobility.
• Symptom Burden: The presence of chronic pain, fatigue, and other systemic symptoms associated with hypermobility is crucial for the HSD diagnosis.
• Exclusion of Other Conditions: A key step in diagnosing HSD is ruling out other connective tissue disorders, particularly hypermobile Ehlers-Danlos Syndrome (hEDS). The diagnostic criteria for hEDS are very specific and require a combination of generalized joint hypermobility, systemic manifestations, and a positive family history, all while excluding other diagnoses. If these hEDS criteria are not fully met, HSD becomes the appropriate diagnosis.
• Multidisciplinary Approach: Diagnosis and management often benefit from a team approach involving rheumatologists, geneticists, physical therapists, occupational therapists, pain management specialists, and other specialists as needed.

Management Strategies and Exercise Considerations

Management of HSD is focused on alleviating symptoms, improving functional capacity, and enhancing quality of life. Exercise plays a critical and foundational role.

Exercise as a Cornerstone of Management

For individuals with HSD, exercise is not just beneficial but essential. However, it must be carefully tailored to avoid exacerbating symptoms or causing injury.

• Focus on Stability and Proprioception: The primary goal is to build muscular strength and control around hypermobile joints, rather than increasing flexibility. Exercises should emphasize joint stability and improve proprioception (the body's awareness of its position in space).
• Low-Impact Activities: Activities like swimming, cycling, elliptical training, and walking are generally preferred over high-impact sports that can stress joints.
• Strength Training: Progressive resistance training is vital.
  • Emphasis on Form: Strict attention to proper form is paramount to prevent hyperextension or engaging end-range joint movements.
  • Controlled Movements: Movements should be slow, controlled, and deliberate, avoiding momentum.
  • Core Strength: A strong core is fundamental for overall stability and reducing strain on peripheral joints.
  • Isometric Exercises: Holding positions can build strength without joint movement.
• Physical Therapy: Working with a physical therapist knowledgeable in hypermobility is highly recommended. They can design individualized exercise programs, teach proper movement patterns, and provide manual therapy techniques.
• Pacing and Listening to the Body: Individuals with HSD often experience significant fatigue and pain. It is crucial to respect the body's limits, incorporate rest days, and avoid pushing through pain. "Boom-bust" cycles (overdoing it followed by crashes) should be avoided.
• Balance Training: Exercises that challenge balance can improve proprioception and reduce the risk of falls.

Other Management Strategies

• Pain Management: This may include pharmacological interventions (NSAIDs, neuropathic pain medications), alongside non-pharmacological approaches such as heat/cold therapy, TENS units, and mindfulness.
• Lifestyle Adjustments: Adequate sleep, stress management techniques, and a balanced diet are important for overall well-being.
• Orthotics and Bracing: In some cases, joint supports or custom orthotics may be used to provide stability and reduce pain.
• Mental Health Support: Given the chronic nature of HSD and its impact on daily life, psychological support (e.g., cognitive behavioral therapy) can be beneficial.

HSD vs. Other Hypermobility Syndromes

Understanding the distinction between HSD, Joint Hypermobility Syndrome (JHS), and Ehlers-Danlos Syndromes (EDS) is crucial:

• Joint Hypermobility Syndrome (JHS): This was an older diagnostic term largely replaced by HSD. HSD provides a more nuanced and comprehensive classification for symptomatic hypermobility.
• Ehlers-Danlos Syndromes (EDS): EDS are a group of heritable connective tissue disorders. There are 13 recognized types, each with specific genetic causes (except for hypermobile EDS, hEDS, where the specific genetic marker is still being sought). HSD is diagnosed when an individual presents with symptomatic hypermobility but does not meet the strict diagnostic criteria for any of the EDS subtypes, particularly hEDS. While there is significant symptom overlap between HSD and hEDS, hEDS typically involves a broader and more severe range of systemic manifestations.

The Role of the Fitness Professional

For fitness professionals, recognizing the signs of hypermobility and understanding HSD is vital for client safety and effective program design.

• Thorough Assessment: Be observant of excessive joint range of motion during assessments and exercises. Inquire about joint pain, fatigue, and a history of sprains or dislocations.
• Collaboration: Encourage clients to consult with their healthcare providers for diagnosis and management. Work collaboratively with physical therapists to ensure exercise programming aligns with medical recommendations.
• Safe Exercise Prescription:
  • Prioritize Stability: Shift focus from flexibility to building strength and stability around joints.
  • Cueing: Use precise verbal and tactile cues to prevent hyperextension (e.g., "soft knees," "slight bend in the elbow").
  • Controlled Movements: Emphasize slow, deliberate movements through a pain-free, controlled range of motion. Avoid ballistic or high-impact exercises.
  • Proprioceptive Training: Incorporate balance exercises and exercises that require fine motor control.
  • Progressive Overload with Caution: Increase resistance or duration gradually, always prioritizing form and client comfort.
• Education and Empowerment: Educate clients about their condition and the importance of consistent, appropriate exercise. Empower them to listen to their bodies and communicate any discomfort.

By adopting a science-informed and cautious approach, fitness professionals can significantly improve the quality of life for individuals living with HSD, helping them build strength, reduce pain, and enhance their functional capabilities safely and effectively.