Nerve injuries (UTD)

Question 1

Highest risk incisions for nerve injury?

Answer 1

Transverse,

• extending beyond lateral margin of inferior rectus (lateral cutaneous branches of ilioinguinal and iliohypogastric nerves)
• 5cm above SP (ilioinguinal/iliohypogastric nerves)
• Near to SP (nerve bundle from inguinal canal)

Question 2

What is a neuroma? Symptoms?

Answer 2

forms at transected or traumatised edge of a nerve. Diagnosed several weeks-months after surgery. Present with persistent lower abdominal or groin pain.

Question 3

Course of ilioinguinal?

Answer 3

ASIS- 3cm medial + 4cm inferior —->
SP- 3cm lateral, 1.7cm superior

Radiates pain to suprapubic area, labia, thigh. Local parenthesis.

Question 4

Course of iliohypogastric?

Answer 4

ASIS: 2cm medial, 1cm inferior —>
SP: 4cm lateral to midline, 5.2cm superior

Question 5

What type of surgery risks damage to femoral nerve?

Answer 5

deep pelvic surgery i.e. abdominal hysterectomy. Increased risk with self-retaining retractors 7.5% vs. 0.7%, narrow pelvis, >4hrs operation.

Question 6

Symptoms of femoral neuropathy

Answer 6

• numbness anteriomedial thigh

- weakness quadriceps and iliopsoas (hip flexion, knee extension) i.e. climbing stairs

Question 7

How can lithotomy cause nerve injury?

Answer 7

Femoral nerve- Hyperflexion of the thigh–> kinking of the nerve under the inguinal ligament –> femoral neuropathy

Peroneal nerve- compression of nerve against lateral aspect of fibula—> acute foot drop

Sciatic- stretching with

• hip flexion and knee extension or
• external hip rotation and knee flexion

Question 8

Symptoms of genitofemoral and lateral femoral cutaneous nerve injury?

Answer 8

GFN- numbness labia, upper medial thigh. no motor defects.

LFCN- numbness/pain antero-posterior lateral aspect of thigh towards knee.

Question 9

Causes of genitofemoral nerve and lateral femoral nerve injury?

Answer 9

retractor blades compression against belly of psoas muscle.
Risk of transection during dissection of the external iliac lymph nodes, mobilisation of iliac vessels, and removal of a large pelvic mass involving pelvic sidewall.

Question 10

Obturator nerve origin and course?

Answer 10

L2-4. Unite posterior to psoas, pass inferiorly over pelvic brim to obturator canal

Question 11

Action of obturator nerve?

Answer 11

motor: thigh adductor muscles

sensory:
anterior division = sensory input from hip to anterior medial thigh
posterior division = below knee

Question 12

Gynaecological surgeries causing obturator nerve injuries?

Answer 12

trans obturator MUS
pelvic lymph node dissection in obturator fossa
endometriosis excision
Paravaginal defect repair with dissection in space of Retzius.

Question 13

Origin of pudendal nerve? Course?

Answer 13

S2-4 nerve roots—> greater sciatic foramen—> lesser sciatic foramen–> pudendal canal (medial obturator internus) –> behind lateral third of the sacrospinous ligament and posterior to the ischial spine.

Question 14

Causes of pudendal nerve injury?

Answer 14

SSF, pelvic reconstructive procedures

Question 15

Symptoms of pudendal nerve injury

Answer 15

perineal, vulva pain worse when sitting
no sensory loss on clinical exam
resolution with pudendal nerve block.

Question 16

What are the symptoms of isolated nerve root injury at S1-4?

Answer 16

Neuropathic symptoms: sharp buttock pain and numbness radiating to the centre of the posterior thigh to the popliteal fossa.