A ganglion cyst is a non-cancerous, fluid-filled sac that typically forms near joints or along the tendon sheaths, most often found on the wrist or hand. A “flare up” refers to an increase in the cyst’s size, pain, or discomfort, making the lump more noticeable. Understanding why these symptoms intensify requires looking at how these structures interact with surrounding tissues. The fluctuating nature of the cyst’s size and associated pain is directly related to the demands placed on the nearby joint or tendon.
The Mechanism of Ganglion Cyst Formation
A ganglion cyst is a collection of fluid enclosed in a sac, originating from the nearby joint capsule or tendon sheath. The prevailing theory suggests that localized trauma or micro-injury weakens the connective tissue, allowing a small pouch to herniate. This pouch acts as a one-way valve, permitting fluid to enter but making it difficult to exit, causing the sac to inflate.
The fluid contained within the cyst is synovial fluid, a clear, viscous lubricant found within healthy joints and tendon sheaths. Once trapped, this fluid thickens into a dense, jelly-like consistency due to the concentration of substances like hyaluronic acid. This mechanical connection to the joint space means that activities affecting joint fluid production directly influence the cyst’s size and sensation.
Repetitive Motion and Joint Stress
The most common reason a ganglion cyst flares up is increased mechanical stress on the adjacent joint or tendon. When a joint undergoes repeated motion, the synovial lining produces an increased volume of synovial fluid to lubricate the moving parts. This normal physiological response provides a greater supply of fluid to the nearby cyst.
Activities involving chronic, repetitive movement, such as extensive typing, prolonged use of hand tools, or sports like gymnastics, force the joint to work harder. As the joint produces more fluid, the pressure within the joint capsule rises, forcing more viscous fluid into the connected cyst sac. This influx increases the cyst’s internal pressure, leading to noticeable swelling and localized pain.
For example, prolonged wrist flexion and extension can compress the dorsal wrist joint, stimulating fluid production and pushing fluid into the ganglion. The increase in volume stretches the cyst wall and presses against surrounding nerves and soft tissues, translating into heightened discomfort. Consequently, the cyst’s size can fluctuate significantly, becoming larger and more painful during periods of high activity and shrinking when the joint is rested. Greater joint movement leads to increased fluid dynamics and greater cyst prominence.
Localized Pressure and Inflammatory Triggers
Beyond chronic overuse, acute triggers like direct impact or sustained pressure can cause a sudden flare-up of pain and swelling. Acute trauma to the area causes immediate inflammation in the surrounding tissues, which irritates the cyst wall and makes existing pressure more painful. This inflammation can also compromise the balance of fluid exchange, causing temporary swelling.
Sustained external pressure can restrict the cyst’s ability to drain or irritate the area, making it feel more prominent. Leaning on the wrist while working or wearing equipment that constantly presses on the cyst causes localized tissue irritation. This external compression may not increase the overall fluid volume but intensifies the pain by physically distorting the cyst and compressing nearby sensory nerve endings.
While the cyst itself is non-inflammatory, general systemic inflammation related to other health conditions can indirectly affect the surrounding joint and soft tissues. This increase in inflammatory mediators can increase sensitivity in the area, causing the cyst to feel more painful and tender, even if its physical size has not changed. These external and acute factors contribute to the episodic nature of ganglion cyst symptoms.