Brachial Plexus: Angela Klein’s Painful Arm Human Gross Anatomy Ernest F. Talarico, Jr., Ph.D. Associate Director of Medical Education Associate Professor of Anatomy & Cell Biology Associate Faculty, Radiologic Sciences Course Director, Human Gross Anatomy & Embryology Indiana University School of Medicine – Northwest (Gary, Indiana)

Patient History 18-year-old female, college student Right handed CC of right shoulder and arm pain x3 months Pain extends down through the 4th and 5th digits of her hand; periodic numbness and tingling in the same distribution Pain is slowly getting worse; intermittent and exacerbated with handwriting Some right arm weakness

Patient Interview Past medical history Allergies Meds Social history The patient has neurofibromatosis. She has had multiple neurofibromas removed since 1998, including one from her nose in 1998 and one from her left medial thigh in 2000. Allergies No known allergies No known toxic environmental or occupational exposures Meds Medications: birth control pills Social history Freshman college student; pre-med Single, no children No travel outside of Indiana in the last 3 years Non-smoker; does not drink alcohol Family history Significant for neurofibromatosis. Mother, brother, grandmother and great-grandmother have neurofibromatosis type 1. Brother has twice had surgery for removal of acoustic neuromas.

Neurofibromatosis is an inherited disorder characterized by the development of multiple tumors (schwannomas and neurofibromas) of the spinal or cranial nerves, tumors of the skin and cutaneous pigmentation. Lesions in the nerves and skin usually appear after puberty and grow slowly or rapidly after this time; typically, the dermal lesions are of little importance in the production of signs and symptoms and they are seldom painful. Occasionally, schwannomas and neurofibromas form on spinal roots and some can grow to considerable size. Intraspinal tumors usually arise from the dorsal root and radicular pain is often the first symptom.

Physical Examination Physical examination revealed an alert, well-developed anxious right-handed white female in mild distress who was nevertheless extremely pleasant and cooperative. Heart rate – 80 BP - 120/80, both arms Cardiac – regular Chest - clear to auscultation Skin multiple cafe-au-lait spots on back, chest, and abdomen multiple small (2-3 mm) dermal neurofibromas on right forearm, left breast, and left ankle; one 1.5 cm soft tumor on left torso just below tenth rib.

Neurological Examination Motor systems: Left upper extremity, trunk, and both lower extremities normal with respect to strength, tone, muscle bulk and lack of adventitious movements. Right upper extremity: There was evidence of weakness in the right biceps, triceps, brachioradialis, wrist extensors, finger extensors, and abductors and extensors on the thumb. The biceps, brachioradialis and triceps reflexes were diminished on the right compared to the left. Sensory systems: Decreased sensation to all modalities along the medial aspect of the right arm. Slight decrease in pinprick sensation on left side of body below C8 dermatome. Light touch, conscious proprioception, and vibration intact bilaterally. positive for Babinski sign on the right

Spinal Nerves (31 pairs) all are mixed nerves (sensory and motor) 4 fiber components Sensory GSA: general somatic afferent GVA: general visceral afferent Motor GSE: skeletal GVE: visceral

31 pairs of spinal nerves Cervical C1 - C4; C5 - C8 Thoracic T1 - T12 Lumbar L1 - L5 Sacral S1 - S5 Cocygeal Cy1 Cervical Plexus ventral rami of C1-C4 Brachial Plexus ventral rami of C5-T1

The Brachial Plexus Innervates all muscles of superior extremity Sensory & motor nerves Anterior division fibers supply flexors Posterior division fibers supply extensors Roots Trunks Divisions Cords Branches Robert Taylor Drinks Cold Beer

Brachial Plexus: Major Branches Musculocutaneous (C5-7) Median Nerve (C6-T1) Ulnar Nerve (C8-T1) Axillary Nerve (C5-6) Radial Nerve (C7-8)

Brachial Plexus: Major Branches Musculocutaneous (C5-7) Biceps Brachii (C5, C6) Coracobrachialis (C5, C6, C7) Brachialis (C5, C6)

Brachial Plexus: Major Branches Median Nerve (C6-T1) Pronator teres Flexor carpi radialis Palmaris longus Flexor digitorum profundus (lateral) Flexor digitorum superficialis Flexor pollicus longus Pronator quadratus and hand mm.

Brachial Plexus: Major Branches Ulnar Nerve (C8-T1, often C7)  + 13 hand mm. Flexor digitorum profundus (medial) Flexor carpi ulnaris

Brachial Plexus: Major Branches Axillary Nerve (C5-6) Deltoid Teres minor

Brachial Plexus: Major Branches Radial Nerve (C5-T1)  12 + anconeus Brachioradialis Triceps brachii (C6, C7, C8) Extensor carpi radialis longus and brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Supinator Abductor pollicus longus Extensor pollicus longus and brevis Extensor indicus

Brachial Plexus: Other Nerves Dorsal Scapular (C5) Rhomboideus major and minor Levator scapulae Suprascapular (C5-6) Supraspinatus Infraspinatus Shoulder joint Subclavian (C5-6) Subclavius Lateral Pectoral (C5-C7) Pectoralis major and minor

Upper Subscapular (C5-6) Subcapularis Thoracodorsal (C6-8) Latissimus dorsi Lower Subscapular (C5-6) Teres major Long Thoracic (C5-7) Seratus anterior Medial Pectoral (C8-T1) Pectoralis minor and major Medial Brachial Cutaneous Medial Antebrachial Cutaneous

Localization of Lesion: Anne Klein Dermatomes Sensory Motor Other Predicted Primary Lesion rt. shoulder C5  medial rt. arm all modalities  rt. biceps brachii musculocutaneous n. C5 < C6 positive for Babinski sign on the right descending pyramidal tracts C6  lt. side of body below C8 dermatome  rt. triceps brachii radial n. C6 < C7, C8 rt. 4th and 5th digits  rt. brachioradialis radial n. C5 < C6 > C7  rt. finger extensors radial n. C6, C7, C8  rt. wrist extensors radial n. C7, C8  rt. thumb abductors and extensors rt. lt. C6 C7 C8 C8 C6 C7 C8 C8

Review of the patient's MRI demonstrated a large paraspinous mass (a dumbbell neurofibroma of cervical spine) with invasion of the neural foramina of C6-7 and C7-T1 and extending out into the brachial plexus. There was some compression of the cervical cord (C6-7) to the left. There was also evidence of tumor invasion of the C7 vertebral body.

Plan Neurosurgery was consulted. A C6-7 laminectomy and C6-7 facetectomy with tumor resection was scheduled for the following week. Oncology consultation.

Patient Outcome The pathology report came back as benign neurofibroma; they did not feel that it was malignant at this time. However, at least one neurologist expressed some concern at this interpretation in light of the pronounced tumor invasion of the C7 vertebral body. Postoperatively, the patient did quite well. Motor strength on the right was only slightly less than that on the left, in spite of the fact that the C6 nerve was sacrificed. The patient's arm pain was improved. At time of discharge, the patient was afebrile and vital signs were stable. She had some mild weakness in her right triceps, her pain was better, and she was ambulating without problem. She was released to the care of her family.