Suprascapular neuropathy (infraspinatus wasting)

What it is

One nerve, the suprascapular nerve, supplies the two rotator cuff muscles on the back of the shoulder blade. It passes through two tight notches on its way, and the branch to infraspinatus turns sharply around the spinoglenoid notch at the outer edge of the blade. If that branch is stretched, compressed, or repeatedly irritated, infraspinatus stops receiving a proper signal and wastes away. At that point the nerve carries almost no sensation, which is why the classic volleyball version is painless.

How volleyball causes it

The follow through of a hard swing whips the arm across the body while infraspinatus contracts hard and the blade rotates, which tightens a ligament over the nerve branch and drags the nerve against the notch. The float serve is repeatedly implicated because of its abrupt, braked arm action. This is one of the most volleyball specific findings in all of sports medicine: surveys of elite players routinely find infraspinatus wasting on the hitting side in a large share of hitters, most of whom have no pain whatsoever. A cyst growing out of a labral tear can also sit in the notch and squash the nerve, and that version usually does hurt.

ServingAttacking

What it feels like

• A hollow or dent below the ridge of the shoulder blade on the hitting side, often spotted first by a teammate or in a photo
• The ball comes off slower with no pain to explain it, and topspin is harder to generate
• Rotating the arm outwards against someone's hand gives way easily on that side
• For many players, nothing at all until strength is tested or someone looks at the shoulder from behind
• In the cyst version, a deep ache at the back of the shoulder that does not behave like tendon pain

Stop and get it seen if

• Weakness that appears over days rather than months, especially after a viral illness or after severe shoulder or shoulder blade pain that fades as the weakness arrives. That pattern suggests a nerve inflammation such as Parsonage Turner syndrome.
• Weakness or numbness spreading beyond outward rotation, into the hand, the grip, or other muscle groups.
• Weakness that follows a neck injury, a stinger, or a heavy collision, particularly with neck pain.
• Pain and weakness together, which raises the chance of a cyst compressing the nerve and is worth imaging sooner rather than later.

What recovery usually looks like

Stages, not a schedule. Everyone moves through these at their own pace, and the ranges are wide because real recoveries are.

1. 1. Working out why

   2 to 8 weeks to a clear diagnosis

   Establish whether this is stretch related irritation from the swing or a cyst pressing on the nerve, because the two are managed completely differently

   • A clinician has tested outward rotation strength side to side
   • Imaging or nerve testing has been done or discussed
   • Hitting volume has been cut back while the picture is clarified

2. 2. Loading what still works

   3 to 6 months

   Strengthen the remaining external rotators and the whole shoulder girdle while reducing the swing volume that keeps provoking the nerve

   • Outward rotation strength stops declining and starts improving
   • Swing and serve velocity stabilising
   • No new movements becoming weak

3. 3. The long tail

   6 to 18 months, sometimes longer

   Nerves recover slowly, and the muscle may never fill back in visibly even when useful strength returns

Ready to play again when

• Outward rotation strength measurably improving, or at minimum stable, on repeat testing
• Swing and serve velocity back to your own normal
• No spread of weakness into other movements
• A clinician has ruled out a cyst compressing the nerve

Keeping it from coming back

This is ordinary training, so unlike the rest of this page it does tell you what to do.

• Build external rotation strength on purpose with side lying external rotation and prone external rotation at 90 degrees, so infraspinatus is both stronger and has a baseline you can notice a loss against.
• Have someone photograph your back and test outward rotation strength side to side once or twice a season. This injury is found by looking, not by waiting for pain.
• Cap float serve volume in any single session. The repeated abruptly braked arm action is the mechanism most often blamed.
• Swing through a full follow through across the body rather than cutting it short and jamming the arm to a stop, which a coach can see and correct.
• Keep posterior shoulder and blade endurance up with band rows and prone Y raises so the arm is decelerated by muscle rather than yanked to a halt at the end of range.