Ganglion Cysts: Nerve Compression, Symptoms, Diagnosis, and Treatment

What happens if a ganglion cyst presses on a nerve?

If a ganglion cyst presses on a nerve, it can lead to a range of neurological symptoms including localized or radiating pain, numbness, tingling, weakness in the affected area, and in some cases, even muscle atrophy, significantly impacting function and comfort.

Understanding Ganglion Cysts

A ganglion cyst is a non-cancerous, fluid-filled sac that typically forms on tendons or joints, most commonly found on the wrist, hand, ankle, or foot. These cysts are essentially out-pouchings of the joint capsule or tendon sheath, filled with a thick, jelly-like synovial fluid. While many ganglion cysts are asymptomatic and may even disappear on their own, their size can fluctuate, and if they grow large enough or are situated in an unfortunate anatomical location, they can exert pressure on surrounding structures. Among the most concerning of these structures are peripheral nerves.

The Anatomy of Nerve Compression

Peripheral nerves are bundles of nerve fibers that transmit signals between the brain and spinal cord and the rest of the body. They are responsible for sensation (touch, temperature, pain), motor control (muscle movement), and autonomic functions (e.g., sweating, blood vessel control). These nerves often run in close proximity to joints and tendons, making them vulnerable to compression from expanding masses like ganglion cysts. When a cyst directly presses on a nerve, it can disrupt the nerve's ability to transmit electrical impulses effectively. This compression can lead to mechanical deformation of the nerve fibers, reduce blood flow to the nerve (ischemia), and trigger an inflammatory response, all of which contribute to nerve dysfunction.

Common Nerves Affected

The specific nerve affected depends on the cyst's location.

• Wrist: Cysts on the dorsal (back) aspect of the wrist can compress branches of the radial nerve, while those on the volar (palm) side may affect the median or ulnar nerves.
• Foot/Ankle: Cysts around the ankle or top of the foot can impinge on branches of the peroneal nerve or the sural nerve, among others.
• Knee: While less common, cysts around the knee can potentially compress the common peroneal nerve.

Signs and Symptoms of Nerve Compression

When a ganglion cyst presses on a nerve, the symptoms experienced are directly related to the specific functions of the affected nerve. These can vary in intensity and character but typically include:

• Pain Characteristics: This is often the most prominent symptom. The pain can be localized directly over the cyst or radiate along the nerve's pathway. It may be described as sharp, shooting, burning, aching, or throbbing. The pain might worsen with specific movements or activities that increase pressure on the cyst or nerve.
• Sensory Disturbances (Paresthesia): Compression can disrupt the nerve's sensory signals, leading to sensations such as:
  • Numbness: A complete or partial loss of sensation in the area supplied by the nerve.
  • Tingling: A "pins and needles" sensation.
  • Burning or Electric Shock Sensations: Indicative of nerve irritation.
• Motor Weakness: If the compressed nerve has motor functions, individuals may experience weakness in the muscles it supplies. This can manifest as:
  • Difficulty with fine motor skills (e.g., gripping objects, buttoning shirts).
  • Reduced strength during specific movements.
  • In severe or prolonged cases, muscle atrophy (wasting away of muscle tissue) can occur, leading to visible thinning of the muscle.
• Autonomic Symptoms: Less commonly, nerve compression can affect autonomic functions, leading to changes in skin temperature, color, or sweating in the affected area.

Why Nerve Compression Occurs

The primary reason a ganglion cyst presses on a nerve is its proximity and size. While some cysts remain small and cause no issues, others can grow significantly or be positioned in a confined anatomical space where nerves are tightly packed. Any increase in the cyst's volume, or even subtle changes in its firmness, can increase the pressure exerted on the adjacent nerve, leading to the onset or worsening of symptoms.

Diagnosis and Evaluation

Accurate diagnosis is crucial. A healthcare professional, often starting with a primary care physician, orthopedist, or neurologist, will conduct a thorough physical examination, assessing the cyst's characteristics, range of motion, and neurological function (sensation, strength, reflexes). Imaging studies such as ultrasound or Magnetic Resonance Imaging (MRI) are invaluable in confirming the presence and size of the cyst, determining its exact relationship to surrounding nerves and vessels, and ruling out other potential causes of nerve compression.

Management and Treatment Considerations

Management of a ganglion cyst that is pressing on a nerve typically requires intervention.

• Observation: This is usually not an option if nerve compression symptoms are present due to the risk of permanent nerve damage.
• Aspiration: A procedure where the fluid is drained from the cyst using a needle. While less invasive, recurrence rates can be high, and it may not fully relieve nerve pressure if the cyst's capsule remains taut.
• Surgical Excision: This is often the most definitive treatment for symptomatic ganglion cysts causing nerve compression. The entire cyst, including its stalk or connection to the joint capsule/tendon sheath, is removed to minimize the chance of recurrence and to relieve pressure on the nerve. Post-operative physical therapy may be recommended to restore full function and mobility.

When to Seek Medical Attention

If you notice a lump or swelling near a joint or tendon, especially if it is accompanied by pain, numbness, tingling, or weakness in the surrounding area, it is imperative to seek prompt medical attention. Early diagnosis and intervention can prevent prolonged nerve compression, which, if left untreated, can lead to irreversible nerve damage and permanent functional deficits.

Conclusion

A ganglion cyst pressing on a nerve is a medically significant event that can lead to debilitating symptoms impacting daily life and physical activity. Understanding the potential for nerve compression and recognizing its signs is crucial for any fitness enthusiast, trainer, or student of kinesiology. While these cysts are benign, their neurological implications are not, underscoring the importance of professional medical evaluation and appropriate management to preserve nerve health and overall function.