Mononeuropathies: trunk 175

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Mononeuropathies: trunk

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Phrenic nerve

Genetic testing NCV/EMG Laboratory Imaging Biopsy Pulmonary function

+ + – + tests

NCV X ray

EMG of the Ultrasound

diaphragm of diaphragm

Fig. 22. Phrenic nerve is in the vicinity of the pericardium. 1 Right. Phrenic nerve. 2 Left.

Phrenic nerve. 3 Anterior portion of Diaphragm

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The phrenic nerve fibers are from C3, 4, and 5. The connection with C3 may be via the inferior ansa cervicalis (cervical plexus). The nerve travels over the anterior scalenus muscle, dorsal to the internal jugular vein, and crosses the dome of the pleura to reach the anterior mediastinum. On the right side, it is positioned next to the superior vena cava and near the right atrium. Sensory branches innervate the pericardium. After transversing the diaphragm, the phrenicoabdominal branches supply the peritoneum of the diaphragm, liver, gall bladder and pancreas. Terminal branches end in the celiac plexus (Fig. 22).

Unilateral lesion: mild dyspnea, or asymptomatic.

Bilateral lesions: age dependent, with babies and small children developing respiratory problems. Newborns with bilateral lesions require ventilation.

Adults are easily dyspneic, particularly upon exertion, and unable to lie in a supine position.

Birth trauma (with or without associated brachial plexus lesions) Idiopathic

Polyneuropathies (AIDP, critical illness, multifocal neuropathy with conduction block)

Neuralgic amyotrophy Chest:

Intrathoracic malignant tumors

Chest operations (intraoperative mechanical or local cooling) Neck wounds

Traction, with upper trunk of brachial plexus damage Chest radiograph

Symptoms

Causes

Frequent sites of lesion

Anatomy

Fig. 23. Diaphragmatic injury.

A Diaphragmatic paralysis. B Inspiration. C Expiration

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Clinically: respiration, ability to recline supine (Fig. 23) Electrophysiology: NCV, EMG of diaphragm

Pulmonary function tests Transdiaphragmatic pressure

Adult onset maltase deficiency

Herpes zoster with motor involvement Motor neuron disease

Myotonic dystrophy Poliomyelitis (spinal)

Polymyositis/Dermatomyositis

Newborn and young children with bilateral lesions need ventilatory support.

Trauma cases can be considered for surgical repair (re-innervation may reach related muscles of the upper extremity, such that breathing discharges can be seen in EMG).

Adults: unilateral lesions may be compensated, but bilateral lesions may require nighttime respiratory support.

Bolton CF, Chen R, Wijdicks EFM, Zifko UA (2004) Neurology of breathing. Butterworth Heinemann, Elsevier Inc (USA)

Cavaletti G (1998) Rapidly progressive multifocal motor neuropathy with phrenic nerve paralysis; effect of nocturnal assisted ventilation. J Neurol 245: 613–616

Chen ZY, Xu JG, Shen LY, et al (2001) Phrenic nerve conduction study in patients with traumatic brachial plexus palsy. Muscle Nerve 24: 1388–1390

References Therapy Diagnosis

Differential diagnosis

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Dorsal scapular nerve

Genetic testing NCV/EMG Laboratory Imaging Biopsy + –

Fig. 24. Dorsal scapular nerve anatomy. 1 Dorsal scapular nerve.2 Levator scapular muscle.3 Minor rhomboid muscle.

4 Major rhomboid muscle

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The dorsal scapular nerve arises from fibers of C4, 5 and travels through the medial scalene muscle and along the medial border of the scapula. This nerve is purely motor, and innervates the levator scapulae and rhomboid muscles (Fig. 24).

Function:

To elevate and adduct the medial border of the shoulder blade (together with the rhomboid muscles).

Almost no symptoms are reported, and usually only with powerful arm movements.

Atrophy of muscles cannot be seen. The scapula becomes slightly abducted from the thorax wall, with outward rotation of the inferior angle.

Neuralgic shoulder amyotrophy Iatrogenic: operations

Nerve is sometimes used as a graft for nerve transplantations.

EMG None

Mumenthaler M, Schliack M, Stöhr M (1998) Läsionen einzelner Nerven im Schulter-Arm- Bereich. In: Mumenthaler M (ed) Läsionen peripherer Nerven und radikuläre Syndrome.

Thieme, Stuttgart, pp 296–311

Symptoms

Signs

Pathogenesis

Diagnosis

Therapy

Reference

Anatomy

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Suprascapular nerve

Symptoms Anatomy

Genetic testing NCV/EMG Laboratory Imaging Biopsy

+ MRI, US

Fig. 25. Suprascapular nerve ana- tomy. 1 Suprascapular nerve.

2 Suprascapular notch/foramen.

3 Spinoglenoid notch

Fibers mainly come from C5 and C6, and travel through the upper trunk of the brachial plexus to innervate the supra- and infraspinatus muscles. The nerve has no cutaneous sensory distribution (Fig. 25).

Dull, aching pain in the posterior aspect of shoulder, which is aggravated by arm use. The patient is unable to lie on his shoulder due to pain. Shoulder elevation and external rotation are weak. Also, slight atrophy of the muscles may be noted.

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Muscle wasting.

Lesion at the suprascapular notch: involvement of both muscles.

Lesion at the spinoglenoid notch: only infraspinatus muscle impairment.

Abnormal transverse scapular ligaments (occasionally bilateral) Arthroscopic shoulder surgery

Closed trauma: the most common cause

Entrapment by the transverse superior or inferior ligaments Neuralgic amyotrophy

Open trauma

Overuse: athletic activities (basketball, volleyball, boxing) or construction trades (e.g. carpentry)

Soft tissue masses: ganglion cysts Surgery: arthroscopy

Systemic lupus erythematosus Trauma: hematoma and fracture Tumors: ganglion, cyst, metastasis

NCV of supraspinatus nerve Needle EMG of muscles MRI, ultrasound

C5 (C6) radicular lesion

“Frozen shoulder”

Rotator cuff tears

Tendinitis of the supraspinatus muscle Upper trunk brachial plexus

Upper trunk brachial plexopathy

Depends on the etiology and severity.

Conservative: rest the limb, analgesics, activity modification, nerve block.

Operative: nerve decompression at entrapment sites.

Replacement surgery: if the lesion appears to be permanent, a transfer from the horizontal part of the trapezoid muscle can be considered.

Depends on the etiology

McCluskey L, Feinberg D, Dolinskas C (1999) Suprascapular neuropathy related to a glenohumeral joint cyst. Muscle Nerve 22: 772–777

Mumenthaler M, Schliack H, Stöhr M (1998) Läsionen einzelner Nerven im Schulter-Arm- Bereich. In: Mumenthaler M, Schliack H, Stöhr M (eds) Läsionen peripherer Nerven und radikuläre Syndrome. Thieme, Stuttgart, pp 261–368

Staal A, van Gijn J, Spaans F (1999) The suprascapular nerve. In: Staal A, van Gijn J, Spaans F (eds) Mononeuropathies. Saunders, London, pp 23–25

Stewart J (2000) Nerves arising from the brachial plexus. In: Stewart JD (ed) Focal peripheral neuropathies. Lippincott, Williams & Wilkins, Philadelphia, pp 157–181

Signs

Causes

Diagnosis

Differential diagnosis

Prognosis Therapy

References

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Subscapular nerve

+ ?

Fig. 26. Subscapular nerve anat- omy. 1 Upper trunk. 2 Posterior cord. 3 Subscapular nerve. 4 Subscapular muscle. 5 Teres major muscle

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Nerve fibers arise from C5 and C6, and travel through the upper trunk and posterior cord of the brachial plexus. The nerve innervates the subscapularis and teres major muscle, to secure the shoulder joint and provide inward rotation of the shoulder (Fig. 26).

Compensation for the function of both muscles is provided by the pectoralis major, latissimus dorsi, and anterior deltoid muscle.

Upon securing shoulder joint, an outward rotation of the upper arm.

Atrophy is not visible, and there are no sensory findings.

Involvement either in association with radiculopathies or with posterior cord brachial plexus injury. There are no entrapment lesions.

EMG of the teres major muscle

C5/C6 radiculopathy, posterior cord lesion of the brachial plexus

Conservative

Symptoms

Signs

Pathogenesis Anatomy

Therapy Diagnosis

Differential diagnosis

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Long thoracic nerve

++ +

Fig. 27. Long thoracic nerve anato- my. 1 Long thoracic nerve. 2 Serra- tus anterior muscle

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Fibers stem from the ventral rami of C5–7, and travel through the dorsal part of the plexus. The nerve traverses the middle scalene muscle, and then passes below the brachial plexus on the thoracic wall. The nerve contains motor fibers exclusively for the serratus anterior muscle (Fig. 27).

Dull ache in the shoulder, affected shoulder seems lower, weakness of arm abduction, no sensory abnormalities.

Atrophy with scapular winging (Fig. 28)

Restriction of abduction and flexion of the arm above shoulder level.

Infection:

Lyme disease, typhoid fever Inflammatory-immune mediated:

Neuralgic amyotrophy: seen mainly in association with other shoulder nerves, particularly with suprascapular nerve. Rarely isolated.

Compressive:

Pressure – part of Rucksack paralysis Iatrogenic:

Intraoperative: thoracotomy, mastectomy, resection of the first rib, lymph node extirpation. Intraoperative positioning.

Symptoms

Signs

Pathogenesis Anatomy

Fig. 28. Long thoracic nerve palsy after thoracic surgery. A Note winging of caudal edge of the scapula. B Scar after thorac- ic surgery

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Trauma:

Acute trauma Birth trauma Blunt trauma

Motor vehicle accidents Open injury

Sports: falls, football, wrestling (traction forces), carrying weights, backpacks, plaster casting, extreme shoulder movements (hitting, punching)

Idiopathic:

No apparent reason

NCV: recording either with needle or surface electrodes EMG

X-ray and CT: for all traumatic lesions

Acute brachial neuropathy Multifocal motor neuropathy Muscular dystrophy

Root lesions C5–C7

“Sprengel” syndrome (hereditary shoulder elevation)

Upper limb predominant, multifocal chronic inflammatory demyelinating polyneuropathy

Winging of scapula is encountered in several conditions

Conservative:

Trauma: neurapraxia, partial lesion (mild axonal lesion) Blunt trauma

Neuralgic amyotrophy Malpositioning Operative:

Trauma: severe axonal lesion, neurotmesis

Generally good-partial lesions are common.

Gorson KC, Ropper AH, Weinberg DH (1999) Upper limb predominant, multifocal chronic inflammatory demyelinating polyneuropathy. Muscle Nerve 22: 758–765

Kim KK (1996) Acute brachial neuropathy – electrophysiologic study and clinical profile.

J Korean Med Sci 11: 158–164

Monteyne P, Dupuis MJ, Sindic CJ (1994) Neuritis of the serratus anterior muscle associated with Borrelia burgdorferi infection. Rev Neurol (Paris) 150: 75–77

Phillips MF (1986) Familial long thoracic nerve palsy: a manifestation of brachial plexus neuropathy. Neurology 36: 1251–1253

Prognosis References Diagnosis

Differential diagnosis

Therapy

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Thoracodorsal nerve

Genetic testing NCV/EMG Laboratory Imaging Biopsy +

Fig. 29. Thoracodorsal nerve anatomy.1 Thoracodorsal nerve.

2 Latissimus dorsi muscle

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Fibers stem from C5–C7 roots. (Only 50% of cases have fibers from C7.) The fibers pass through the upper and middle trunks and the posterior cord, and continues with the lower subscapular nerve.

Occasionally this nerve is a branch of the axillary and radial nerves.

A motor branch goes to the latissimus dorsi muscle, and may also innervate the teres major muscle.

Both muscles are adductors and inward rotators of the scapulohumeral joint and help to bring down the elevated arm (see Fig. 29).

Few clinical symptoms, weakness compensated in part by pectoralis major and teres major muscles.

Signs:

Atrophy, and slight winging of the inferior margin of the scapula

Motor: Latissimus dorsi: weakness in adduction and medial rotation of shoulder and arm.

Isolated lesion is very uncommon.

Neuralgic amyotrophy (rarely)

Plexus lesions: injury in association with posterior cord or more proximal brachial plexus lesions.

EMG

Plexus: posterior cord lesions, upper/middle trunk lesions Radicular: C5–C7 lesion

Conservative. Surgical interventions are not necessary because of the minor dysfunction.

Due to this fact, this muscle can be used for grafting to the biceps brachii and outward rotators of humeroscapular joint.

Good

Symptoms

Causes

Diagnosis

Differential diagnosis

Therapy

Prognosis

Anatomy

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Patients note painless atrophy.

Weakness and atrophy of the pectoral muscle. Compensatory hypertrophy of other chest muscles.

Lateral pectoral nerve:

Receives fibers from C5–7 (lateral cord of plexus) and supplies upper part of pectoral muscle.

Medial pectoral nerve:

Receives fibers from C8/T1 and supplies lower part of pectoral muscle.

Aplasia

Entrapment in hypertrophies of minor pectoral muscle Neck dissection

Weight lifting

Bird SJ (1996) Acute focal neuropathy in male weight lifters. Muscle Nerve 19: 897–899

Pectoral nerve

Causes

Reference

Anatomy

Symptoms

Signs

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Thoracic spinal nerves

Symptoms

Signs

Pathogenesis Anatomy

(+) + +

The twelve pairs of thoracic spinal nerves innervate all the muscles of the trunk and surrounding skin, except the lumbar paraspinal muscles and overlying skin. Dorsal and ventral rami can be affected.

Three groups: T1, T2–T6, T7–T12.

a) T1 and C8: first intercostal nerve b) T2–T6: innervation of the chest wall

T2 is the intercostobrachial nerve (see also brachial plexus) c) T7–11: Thoracoabdominal nerves

T12 is the subcostal nerve

Pain, sensory symptoms, depending on whether dorsal or ventral rami are affected.

Muscle weakness may be difficult to assess, except in the case of abdominal muscles, where bulging occurs during coughing or pressure elevation.

Metabolic:

Diabetic truncal neuropathy Infectious:

Herpes: Pre-herpetic neuralgia (1–20 days before onset) Herpetic neuralgia

Post-herpetic neuralgia Lyme disease

Compressive:

Abdominal cutaneous nerve entrapment

Notalgia paresthetica: involvement of dorsal radicular branches Thoracic disc disease (rare)

Neoplastic:

Invasion at the apex of the lung Schwannoma

Vertebral metastases Traumatic:

Trauma

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Iatrogenic:

Postoperative (abdominal surgery, post mastectomy, and thoracotomy)

Laboratory: Fasting glucose, serology (herpes, borreliosis)

CSF examination (e.g., pleocytosis and antibodies in Lyme disease) Imaging: vertebral column: plain X-ray, CT, MRI

Electrophysiology: NCV of intercostal nerves is difficult and not routinely done.

EMG: paraspinal muscles, intercostals, abdominal wall muscles

Local painful conditions of the vertebral column (disc herniation, spondylodis- citis, metastasis)

“Intercostal neuralgia”

Muscle disease with abdominal weakness Slipping rib/Cyriax syndrome

Depends on the etiology

Daffner KR, Saver JL, Biber MP (2001) Lyme polyradiculoneuropathy presenting as increas- ing abdominal girth. Neurology 40: 373–375

Gilbert RW, Kim JH, Posner JB (1978) Epidural spinal cord compression from metastatic tumor; diagnosis and treatment. Ann Neurol 3: 40–51

Love JJ, Schorn VG (1965) Thoracic disc protrusions. JAMA 191: 627–631

Stewart JD (1999) Thoracic spinal nerves. In: Stewart JD (ed) Focal peripheral neuropathies.

Lippincott, Philadelphia, pp 499–508

Vial C, Petiot P, Latombe D, et al (1993) Paralysie des muscles larges de l àbdomen due a une maladie de Lyme. Rev Neurol (Paris) 149: 810–812

Differential diagnosis

Therapy

References

Diagnosis

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Differential diagnosis

The intercostal nerves are the ventral rami of the thoracic spinal nerves. They innervate the intercostal (first 6) and abdominal muscles (lower 6), as well as skin (via anterior and lateral branches). The first ventral ramus is part of the brachial plexus.

Intercostobrachial nerve:

Originates from the lateral cutaneous nerve of the second and third intercostal nerves to innervate the posterior part of the axilla.

Often anastomizes with the medial cutaneous nerve of the upper arm (stem- ming from medial cord of brachial plexus).

The 7–11th ventral rami are called the thoracoabdominal nerves.

The 12th thoracic nerve is the subcostal nerve.

Radicular pain (beltlike)

Over the thorax cavity, no muscle weakness can be detected. However, bulging of abdominal muscles may be apparent.

Abdominal cutaneous nerve entrapment Diabetic truncal neuropathy

Herpes zoster Notalgia paresthetica

Post-operatively: abdominal, retroperitoneal, and renal surgery.

Traumatic lesions

Thoracic disc trauma (rarely) Vertebral metastasis

Laboratory: fasting glucose Serology (herpes, Lyme disease) Imaging: vertebral column, MRI

Electrophysiology is difficult in trunk nerves and muscles Pain may be of intra-thoracic, intra-abdominal, or spinal origin.

Compartment syndrome of the rectus abdominis muscle

Intercostal nerves

Symptoms Signs

Pathogenesis

Diagnosis Anatomy

(+) + – Osseous structures of

vertebral column and ribs

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Costochondritis

Head zones (referred pain) Hernia

“Intercostal neuralgia”

Pseudoradicular pain

Rupture of the rectus abdominis muscle Slipping rib

Thoraconeuralgia gravidarum Depending on etiology

Krishnamurthy KB, Liu GT, Logigian EL (1993) Acute Lyme neuropathy presenting with polyradicular pain, abdominal protrusion, and cranial neuropathy. Muscle Nerve 16:

1261–1264

Mumenthaler M, Schliack H, Stöhr M (1998) Läsionen der Rumpfnerven. In: Mumenthaler M, Schliack H, Stöhr M (eds) Läsionen peripherer Nerven und radikuläre Syndrome.

Thieme, Stuttgart, pp 368–374

Staal A, van Gijn J, Spaans F (1999) The intercostal nerves. In: Staal A, van Gijn J, Spaans F (eds) Mononeuropathies. Saunders, Londons, pp 84–86

Stewart J (2000) Thoracic spinal nerves. In: Stewart J (ed) Focal peripheral neuropathies.

Lippincott, Williams & Wilkins, Philadelphia, pp 499–508

Thomas JE (1972) Segmental zoster paresis: a disease profile. Neurology 22: 459–466

Therapy

References

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Symptoms

Signs

Differential diagnosis

Anatomy

Originates from lateral cutaneous nerve of second and third intercostal nerves to innervate the posterior part of the axilla. This nerve often anastomizes with the medial cutaneous nerve of the upper arm (from the medial cord of the brachial plexus).

Pain in the axilla, chest wall, or thorax. Often occurs one or two months after mastectomy. Reduced movement of the shoulder enhances pain.

Sensation is impaired in the axilla, chest wall, and proximal upper arm.

Operations in the axilla (removal of lymph nodes) Following surgery for thoracic outlet syndrome Lung tumors

Assa J (1974) The intercostobrachial nerve in radical mastectomy. J Surg Oncol 6: 123–126

Intercostobrachial nerve

Reference

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Iliohypogastric nerve

Fig. 30. lliohypogastric nerve anatomy. 1 lliohypogastric nerve. 2 llioinguinal nerve. 3 Obturator nerve. 4 Genitofemo- ral nerve

Fibers originate at L1, then emerge from the lateral border of the psoas, crossing the lower border of the kidney, then the lateral abdominal wall. Then the nerve crosses the transverse abdominal muscle above iliac crest and passes between the transverse and oblique internal abdominal muscles. Finally two branches are given off: the lateral anterior and anterior cutaneous nerves.

Burning and stabbing pain in the ilioinguinal region, which may radiate to- wards the genital area or hip. Symptoms increase when walking.

Difficult to examine. Spontaneous bulging of abdominal wall. Sensory deficit may be present. Tinel’s sign over a surgical scar may be observed. Slight flexion of hip while standing.

Symptoms

Signs

Anatomy

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Electrophysiology is not routinely available. Clinical distribution.

Spontaneous entrapment in abdominal wall, surgery, hernioraphy, appendectomy, abdominoplasty, nephrectomy, endometriosis.

Steroids locally, scar removal, neurolysis.

Diagnosis

Therapy

Differential diagnosis

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Ilioinguinal nerve

Fig. 31. llioinguinal nerve anat- omy. a A-female. 1 llioinguinal nerve. b B-male. 1 lliohypogas- tric nerve. 2 llioinguinal nerve

Fig. 32. Ilioinguinal nerve le- sion after gynecologic surgery.

The sensory loss (marked with a ball pen) reached almost the labia

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The ilioinguinal nerve originates with fibers from T12 and L1. The motor component innervates the internal and external oblique muscles, and the transverse abdominal muscle.

The sensory component covers the skin overlying the pubic symphysis, the superomedial aspect of the femoral triangle, the anterior scrotal surface, and the root of the penis/labia majora and mons pubis (Fig. 31).

Hyperesthesia, sometimes with significant pain over the lower abdominal quadrant and the inguinal region and genitalia (Fig. 32).

Weakness of lower abdominal muscles, hernia.

Abdominal operations with a laterally placed incision Biopsy

Endometriosis, leiomyoma, lipoma Herniotomy

Iliac bone harvesting Pregnancy, child birth

Spontaneous entrapment – “inguinal neuralgia“

Studies: no standard electrophysiologic techniques are available

Local anesthetic infiltration

Surgical exploration and resection of the nerve

Genitofemoral neuropathy Inguinal pain syndrome Iliohypogastric neuropathy L1 radiculopathy (very rare)

Dawson DM (1990) Miscellaneous uncommon syndromes. In: Dawson DM (ed) Entrap- ment neuropathies. Little Brown, Boston, pp 307–323

Komar J (1971) Das Ilioinguinalis Syndrom. Nervenarzt 42: 637–640

Mumenthaler M (1998) Läsionen einzelner Nerven im Beckenbereich und an den unteren Extremitäten, 7. Aufl. G. Thieme Verlag, Stuttgart, pp 393–464

Purves JK, Miller JD (1986) Inguinal neuralgia; a review of 50 patients. Can J Surg 29:

585–587

Stulz P, Pfeiffer KM (1982) Peripheral nerve injuries resulting from common surgical procedures in the lower portion of the abdomen. Arch Surg 117: 324–327

Clinical syndrome

Signs Causes

Diagnosis Therapy

Differential diagnosis

References

Anatomy

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Genitofemoral nerve

Symptoms

Signs Causes

Diagnosis

Differential diagnosis

Therapy

Prognosis References Anatomy

The nerve originates from the ventral primary rami of L1 and L2, then runs along the psoas muscle to the inguinal ligament. In the inguinal canal the genital branch runs with the ilioinguinal nerve, to supply the skin of the mons pubis and labium majus. The genital branch also innervates the cremaster muscle, while the femoral branch innervates the proximal anterior thigh.

May give rise to continuous pain, sometimes called “spermatic neuralgia”.

Can present as a post-operative inguinal neuralgia.

Paresthesias (may be painful) of the medial inguinal region, upper thigh, side of scrotum, and labia majora.

Tenderness in the inguinal canal. Cremaster reflex unreliable.

Appendectomy Bone graft removal Hernioraphy Nephrectomy Trauma

Tumors (uncommon) Tuberculosis

Varicocele testis

No electrophysiologic studies are available Diagnostic anesthetic blockade

L1, 2 radiculopathy Iliohypogastric neuropathy Ilioinguinal neuropathy

Anesthetic blockade Operative neurolysis

Good

Magee RK (1942) Genitofemoral causalgia (a new syndrome). Can Med Assoc J 46: 326–

329

Staal A, van Gijn J, Spaans F (1999) The genitofemoral nerve. In: Staal A, van Gijn J, Spaans F (eds) Mononeuropathies. Saunders, London, pp 95–96

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Superior and inferior gluteal nerves

+ +

Fig. 33. Superior gluteal nerve anatomy. 1 Superior gluteal nerve

Fig. 34. Trendelenburg’s sign, indicating weakness of the hip abductors (gluteus medius mus- cle). A Standing on both feet the pelvis remains in horizontal po- sition. B When the patient stands on his left leg, his pelvis tilts to the right side. This patient had a left gluteus medius nerve lesion, caused by an iliac aneurysm. Note that the greater gluteal muscles are not affected

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Superior gluteal nerve:

Originates with the posterior branches from ventral rami of L4–S1, to innervate the gluteus medius and minimus muscles.

Inferior gluteal nerve:

Originates with the posterior portions of L5 and S1, and ventral primary rami of S2. It innervates the piriformis and gluteus maximus muscles.

Superior:

Causes Trendelenburg’s gait. Excessive drop of the non-weight-bearing limb and a steppage gait on the unaffected side. Hip abduction is weak, sensation is normal.

Inferior:

Causes buttock pain and weak hip extension (weakness getting up).

Superior:

Misplaced injection, trauma, hemorrhage, arthroplasty, aneurysm.

Inferior:

Rarely isolated, often associated with the sciatic nerve, occasionally with pudendal nerve. Colorectal carcinoma, injections, trauma.

EMG, imaging

Sacral plexus lesion Hip and pelvic pathology

Grisold W, Karnel F, Kumpan W, et al (1999) Iliac artery aneurysm causing isolated superior gluteal nerve lesion. Muscle Nerve 22: 1717–1720

Rask MR (1980) Superior gluteal nerve entrapment syndrome. Muscle Nerve 3: 304–307 Wilbourn AJ, Lesser M (1983) Gluteal compartment syndrome producing sciatic and gluteal mononeuropathies: a report of two cases. Electrencephal Clin Neurophysiol 55:

45–46

Symptoms and Signs

Pathogenesis

Diagnosis

Differential diagnosis

References

Anatomy

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Pudendal nerve

+ – +

Fig. 35. Pudendal nerve anato- my. a 1 Pudendal nerve. 2 Perineal nerves. 3 Dorsal nerve of clitoris. 4 Inferior rectal nerves. b 1 Perineal nerves. 2 Pudendal nerves

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Fig. 36. Pudendal nerve anato- my. a1 Dorsal nerve of penis. 2 Pudendal nerve. 3 Perineal nerves. b 1 Perineal branch of cutaneous femoral posterior nerve.2 Pudendal nerve. 3 Rec- tal inferior nerves. 4 Bulbo spongiosus muscle. 5 External anal sphincter muscle

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Clinical picture

Signs Causes

Anatomy

The nerve originates from S2–S4, and passes through the sciatic foramen and pudendal canal. Its terminal branches are the inferior rectal nerve (innervating the levator ani, external anal sphincter muscles, and skin around the anus), the perineal nerve (innervating the external urethral sphincter muscles, bulbocavernosus, perineum, and dorsal aspect of scrotum/labia), and the terminal branch of the pudendal nerve (providing sensation to the clitoris, glans penis, dorsal region of the penis) (see Fig. 35 through 37).

Perineal sensory symptoms, sexual dysfunction.

Bilateral lesions may cause urinary or fecal incontinence, impotence/anor- gasmy, and sensory disturbances.

Sphincter reflexes (anal, bulbocavernosus reflex absent)

Selective injury is rare External compression:

Perineal, post-operative of hip fractures Long bicycle rides

Suturing through sacrospinal ligament during colonoscopy Stretch:

Straining during defecation Childbirth

Pelvic fracture Pelvic surgery Fig. 37. Pudendal nerve anato-

my. 1 Cutaneous femoris posterior nerve. 2 Labial/scrotal nerves.3 Anococcygeal nerve

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Hip dislocation

Intraarticular foreign body

Polyneuropathy

Radicular lesion (S2–S4) Sacral plexus

Structural abnormalities of the pelvic floor or viscera

EMG of external anal sphincter Bulbocavernosus reflex

Pudendal SEP

Anorectal manometry, urodynamic examinations Imaging

Amarenco G, Ismael SS, Bayle B, et al (2001) Electrophysiological analysis of pudendal neuropathy following traction. Muscle Nerve 24: 116–119

Podnar S, Vodusek DB (2001) Standardization of anal sphincter electromyography: utilty of motor unit potential parameters. Muscle Nerve 24: 946–951