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Expect the Unexpected with Deltoid Muscle Paralysis

Scientists have numbered and mapped out all the nerves in the body. They know which parts of the body get which nerve connection. For example, nerves in the neck supply sensation and muscle contraction to the neck, chest, and arms. When a patient develops arm numbness and weakness, doctors can usually trace the cause by the location of the symptoms.

Paralysis of the deltoid muscle in the upper arm is usually caused by pressure on the C5 spinal nerve root. It is expected that problems with this nerve would occur from problems in the C4/5 level in the neck. In this study, however, doctors report finding deltoid paralysis with problems above and below the C4/5 level. Doctors also tracked peoples' symptoms after surgery to take pressure off the nerve to the deltoid muscle.

All patients were tested for pain levels and muscle strength. X-rays and MRIs were done to find the cause of the pressure. The tests showed what level was compressed. Disc herniation and bone spurs were the most common problems. Surgery to remove these damaged tissues and to fuse the neck was done for all patients.

The patients all got relief and recovery from pain and paralysis after the operation. These results show that deltoid paralysis can occur with problems above or below the usual C4/5 level. The authors think differences occur in how and where spinal nerves go. They don't follow the same path in everyone. This helps to explain why someone with problems at C3/4 or C5/6 could end up with problems in the C5 nerve going to the deltoid muscle.

Surgery is generally successful in restoring normal function. The authors advise early surgery to get the best results. They think the deltoid muscle does better if it hasn't been paralyzed too long. Knowing that problems with the C5 nerve can be coming from one level above or below C4/5 can help doctors make the right diagnosis and offer the best treatment.

References: Han Chang, et al. Clinical Analysis of Cervical Radiculopathy Causing Deltoid Paralysis. In European Spine Journal. December 2003. Vol. 12. No. 6. Pp. 517-521.

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