137 The conus medullaris terminates at vertebrum L1. The lower segmental ventral and dorsal lumbar and sacral nerve roots form the cauda equina. The lumbar nerve roots run obliquely downwards and laterally. The sacral spinal nerves divide into rami within the spinal canal. Each ramus passes through a pelvic sacral foramen to join the sacral plexus; each dorsal ramus emerges through a dorsal sacral foramen to supply paraspinal muscles and the skin over the sacral and medial gluteal areas. The cauda equina is loosely enveloped by arachnoid membrane, from which a sleeve extends to cover each nerve root. As a nerve passes into the nerve foramen it is invested in a short sleeve of dura. Acute central (disc) herniation: Pain bilaterally in the buttock, sacral, perineal, and posterior leg regions, and sphincter dysfunction. Chronic: Back pain, perineal pain, paresthesias. Urinary and erectile dysfunction may occur in men. Acute: Weakness of S1 and S2 muscles, sensory loss from soles to perineal region with saddle anesthesia. Loss of anal wink. Roots positioned most laterally (lower lumbar and upper sacral) are most often affected, while the central roots can be spared (S3–S5). Thus, the bladder is often spared. Chronic: Similar signs as acute injury. Muscle wasting in chronic conditions may resemble chronic polyneuropathy. Toxic: Anesthesia (spinal and epidural anesthesia) Contrast media Cytotoxic drugs (intrathecal methotrexate) Radiation: TRI (transient radicular irritation) Spinal arachnoiditis Genetic testing NCV/EMG Laboratory Imaging Biopsy +++ Cauda equina Anatomy Symptoms Signs Pathogenesis 138 Vascular: AV fistulas (spinal/dural) may mimic spinal stenosis Cauda equina claudication Spinal subarachnoid hemorrhage Infectious: AIDS: CMV infections Herpes simplex infection Others: cryptococcal, syphillis, tuberculosis Inflammatory/Immune: Bechterew’s disease Neoplastic: Ependymoma Neurofibroma Rare: dermoid, hemangioblastoma, lipoma, meningioma, paragangliomas, schwannoma Malignant disease: astrocytoma, bone tumors, leptomeningeal carcinomatosis, metastases, multiple myeloma Acute central disc protrusion: A large acute central disc may cause acute and dramatic bilateral sciatic pain. Also pain in the buttock and perineal regions, numbness and weakness of the legs, and sphincter dysfunction. “Saddle anesthesia”. Chronic central disc: Mimics tumors of the conus medullaris and is associated with perineal pain, paresthesias and urinary dysfunction. Trauma: Fractures of the sacrum Spinal surgery Vertebral injury Genetic: Tethered cord Imaging of bony structures and MRI. CSF in inflammatory conditions Electrophysiology: EMG of S1–S3 muscles Sensory conductions Reflex techniques (F waves, H reflex) Spincter EMG including bulbocavernosus reflex Magnetic stimulation Spinal cord (epiconus- medullary lesions) Rapidly ascending polyneuropathy Sensorimotor neuropathies with autonomic involvement Depends on the cause Diagnosis Differential diagnosis Therapy 139 Guigui P, Benoist M, Benoist C, et al (1998) Motor deficit in lumbar spinal stenosis: a retrospective study of a series of 50 patients. J Spinal Disord 11: 283–288 Hoffman HJ, Hendrick EB, Humphreys RB, et al (1976) The tethered spinal cord; its protean manifestation, diagnosis and surgical correction. Childs Brain 2: 145–155 Tyrell PNM, Davies AM, Evans N (1994) Neurological disturbances in ankylosing spondyli- tis. Ann Rheum Dis 53: 714–717 Yates DAH (1981) Spinal stenosis. J R Soc Med 74: 334–342 References 141 Mononeuropathies 143 Mononeuropathies are an essential part of clinical neurology. The clinical diagnosis depends on the knowledge of anatomy, the presentation of clinical syndromes and numerous etiologies. The individual mononeuropathies of the upper extremity, the trunk and the lower extremities are discussed by the anatomic course of the nerve , anomalies and their symptoms and signs. The most likely causes of damage are discussed and differential diagnosis is considered. Therapeutic aspects and if available prognosis are mentioned. The references are limited to a few key references. Most of our artist‘s illustrations are devoted to this section. The clinical photography should help the reader to identify the patient’s abnormalities. The concept is an accurate and brief description of the most important clinical features. The trunk nerves which are often neglected are summarized in a separate subsection. Introduction 145 Mononeuropathies: upper extremities 147 Genetic testing NCV/EMG Laboratory Imaging Biopsy ++ Axillary nerve Fig. 1. 1 Axillary nerve. 2 Del- toid muscle. 3 Teres minor muscle 148 Symptoms Anatomy Fibers originate from roots of C5-C6, and travel through the upper trunk and posterior cord of the plexus. The nerve continues through the axilla (quadrilateral space), with a motor branch to the teres minor and two further divisions. The posterior division innervates the posterior head of the deltoid muscle and gives off the superior lateral cutaneous nerve. The anterior division innervates the lateral and anterior heads of the deltoid muscle (see Figs. 1 and 2). Weakness in elevation of the upper arm. Signs: Atrophy, and flattening of the lateral shoulder. Reduction of external rotation and shoulder adduction (teres minor muscle). Deficits of shoulder abduction, flexion, and extension (deltoid muscle). Shoulder abduction is the most clinically relevant deficit, as the other muscles are well compensated. Sensory: Deficits are variable (and may be absent), involving lateral shoulder and upper arm. Fig. 2. Quadrilateral space. 1 Teres minor. 2 Teres major. 3 Medial and lateral-caput lon- gum of triceps muscle. 4 Neck of humerus. 5 Circumflexor hu- meri posterior artery 149 Differential diagnosis Diagnosis Acute trauma: Anterior dislocation of the humeral head, fractures of the proximal humerus or scapula. Prognostic factors are the time between dislocation and reposition, presence of hematoma, and age. Blunt trauma: Heavy objects striking shoulder, contact sports, falls on shoulder Open injury: Gunshot, arthroscopy, intramuscular injection Burner syndrome: Anterior nerve lesion in association with other nerve structures due to blows to superior shoulder Neuralgic amyotrophy: Mainly in association with other nerves, particularly with the suprascapular nerve, and rarely isolated Malpositioning: Sleep, anesthesia Tumors: Benign nerve sheath tumors, osteochondroma Quadrilateral space syndrome: Neurovascular compression syndrome, with pain, paresthesias (non-anatomic distribution throughout the limb), and shoulder tenderness Birth trauma Infectious: Measles Electrophysiology: Axillary nerve latency CMAP most relevant Disadvantages: No sensory conduction studies. The only stimulation site is proximal to common entrapment locations. Hence, conduction block is hard to differentiate from axonal lesion in the early stage of nerve injury. EMG: teres minor and all three heads of the deltoid muscle. Imaging: Traumatic lesions, quadrilateral space syndrome, space occupying structures X-ray and CT: all traumatic lesions MRI: teres minor atrophy often seen in quadrilateral space syndrome Subclavian arteriography: to demonstrate posterior humeral artery occlusion with shoulder abduction and external rotation. Axillary arteriogram, duplex scan: pseudoaneurysm Radicular C5 lesion Brachial plexus posterior cord lesion Causes 150 Therapy References Musculoskeletal: Multiple steroid injections in the deltoid muscle Periarthropathia Rotator cuff rupture Rupture of the deltoid muscle Multifocal motor neuropathy Chronic inflammatory demyelinating polyneuropathy Conservative: Trauma: neurapraxia, partial lesion (mild axonotmesis) Blunt trauma Neuralgic amyotrophy Malpositioning ± Quadrilateral space syndrome Operative: Trauma: severe axonotmesis, neurotmesis Extrinsic space occupying lesions Good Lester B, Jeong GK, Weiland AJ, et al (1999) Quadrilateral space syndrome: diagnosis, pathology, and treatment. Am J Orthop 28: 718–722 Perlmutter GS (1999) Axillary nerve injury. Clin Orthop 368: 28–36 Prognosis [...]... to the hypothenar region of palm Also, loss of dexterity and loss of control of the small finger Signs Sensory distribution of the ulnar nerve: ulnar aspect of the palm, volar surface of the fifth digit, and ulnar half of the fourth digit Sensory distribution of the dorsal sensory branch: ulnar aspect of dorsum of hand, and fourth and fifth digit Motor disability: weakness of pinch between thumb and... humeral exostosis Neurology 54: 49 4 49 6 Patel R, Bassini L, Magill R (1991) Compression neuropathy of the lateral antebrachial cutaneous nerve Orthopedics 14: 173–1 74 Sander HW, Quinto CM, Elinzano H, et al (1997) Carpet carrier‘s palsy; musculocutaneous neuropathy Neurology 48 : 1731–1732 Young AW, Redmond D, Belandes BV (1990) Isolated lesion of the lateral cutaneous nerve of the forearm Arch Phys Med... Nerve 12: 347 –352 Campbell WW, Pridgeon RM, Riaz G, et al (1991) Variations in anatomy of the ulnar nerve at the cubital tunnel: pitfalls in the diagnosis of ulnar neuropathy at the elbow Muscle Nerve 14: 733–738 Chiou-Tan FY, Reno SB, Magee KN, et al (1998) Electromyographic localization of the palmaris brevis muscle Am J Phys Med Rehabil 77: 243 – 246 Holtzman RN, Mark MH, Patel MR, et al (19 84) Ulnar... lateralis nerve 3 Coracobrachialis muscle 4 Short head of biceps muscle 5 Long head of biceps muscle 6 Brachialis muscle 152 Fig 4 Biceps pathology A Atrophy of the biceps brachii in a patient with neuralgic shoulder amyotrophy Note the absent relief of the muscle B Biceps tendon rupture Typical clinical manifestation with flexion of the elbow Fig 5 Nerve metastasis of a carcinoid tumor in the musculocutaneous... double anastomotic innervation of the thenar muscles J Anat 109: 46 1 46 6 Hopf HC (1990) Forearm ulnar to median anastomosis of sensory axons Muscle Nerve 13: 6 54 656 Padua L, Paciello N, Aprile I, et al (2000) Damage to peripheral nerves following radiotherapy at the wrist J Neurol 247 : 313–3 14 Rosenbaum RB, Ochoa JL (1993) Carpal Tunnel Syndrome and other disorders of the median nerve Butterworth... paralysis of the descending branch of the posterior interosseus nerve J Bone Joint Surg 70: 140 2– 140 3 Linscheid RL (1965) Injuries to radial nerve at the wrist Arch Surg 91: 942 – 946 Marmor L, Lawrence JF, Dubois EL (1967) Posterior interosseus nerve palsy due to rheumatoid arthritis J Bone Joint Surg Am 49 (381): 383 Spinner M, Freundlich BD (1968) Posterior interosseus nerve palsy as a complication of Monteggia... and 14) : Nocturnal paresthesias in the hand, may radiate up to shoulder Paresthesias during daytime, particularly during the use of the hand with forced flexion or extension at the wrist 159 Local pain at the wrist Sensory symptoms of the first three digits and the radial half of the fourth digit Most commonly, hypesthesia is restricted to the volar tip of the second and third finger Weakness of thumb... split of carpi transversum, either via endoscopic or open technique Prognosis for both techniques is good (85% success) 161 Atroshi R, Johnsson R, Ornstein R (1997) Endoscopic carpal tunnel release: a prospective assessment of 255 consecutive cases J Hand Surg (Br) 22: 42 47 Cseuz KA, Thomas JE, Lambert EH, et al (1966) Long term results of operation for carpal tunnel syndrome Mayo Clin Proc 41 : 232– 241 ... longus 7 Abductor digiti minim) muscle 156 Fig 9 Transsection of the median nerve and sural nerve interplantate in a 24 month follow up A Orators hand prior to operation, B after 24 months the long flexors of the thumb and particularily the index finger show increased mobility Fig 10 Acute carpal tunnel syndrome A Local painful swelling of the left volar wrist, sensory loss in median nerve distribution... neurapraxia, partial lesion Forearm Posterior interosseus nerve (PIN): Purely motor branch, supplies dorsiflexor muscles of the fingers Dull pain in the deep extensor muscle mass (occasionally sharp pain), “inability to use the hand”, no sensory symptoms Radial deviation of the hand, weak wrist extension, weak extension of all digits (in a complete lesion) weak extension of fourth and fifth digits (in a partial . and lateral-caput lon- gum of triceps muscle. 4 Neck of humerus. 5 Circumflexor hu- meri posterior artery 149 Differential diagnosis Diagnosis Acute trauma: Anterior dislocation of the humeral. nerve. 3 Coracobrachi- alis muscle. 4 Short head of bi- ceps muscle. 5 Long head of biceps muscle. 6 Brachialis muscle 152 Fig. 4. Biceps pathology. A At- rophy of the biceps brachii in. Brain 2: 145 –155 Tyrell PNM, Davies AM, Evans N (19 94) Neurological disturbances in ankylosing spondyli- tis. Ann Rheum Dis 53: 7 14 717 Yates DAH (1981) Spinal stenosis. J R Soc Med 74: 3 34 342 References 141 Mononeuropathies 143 Mononeuropathies