a. L2
b. L3
c. L4
d. L5
e. S1
2. Spondylolysis (pars defect) is most widely believed to be caused by what?
a. A congenital defect in the pars
b. An acute traumatic defect in the pars
c. A stress fracture of the pars
d. A benign neoplasm involving the pars
e. None of the above
3. Cauda equina compression (CEC) syndrome is most typically manifested by:
a. Foot-drop
b. Severe back pain
c. Parasthesias in a nonanatomic distribution
d. Urinary retention
e. Priapism
4. A sequestered disk herniation refers to:
a) Bulging of the nucleus through a weakened annulus
b) Rupture of the nucleus through the annulus
c) Rupture of the nucleus through the annulus and the posterior longitudinal ligament
d) Rupture of the nucleus through the posterior longitudinal ligament
e) Separation of a herniated fragment from the disk
5. A 30-year-old man underwent an anterior lumbar discectomy and fusion at L4-L5 and L5-S1 through an anterior retroperitoneal approach 1 month ago. He now reports that he is unable to obtain and maintain an erection. The most likely cause of this condition is:
a) Disruption of the sympathetic nerves during anterior lumbar exposure
b) Traction on the parasympathetic nerve at the L4-L5 level
c) Not related to the surgical dissection
d) Injury to the pudendal nerves in the anterior sacral region during dissection at the L5-S1 level
e) Sexual dysfunction secondary to retrograde ejaculation
6. Which of the following antibiotics would not be useful in staphylococcal vertebral osteomyelitis:
a. Cefuroxime
b. Nafcillin
c. Cefazolin
d. Ciprofloxicin
e. Tobramycin
7. Which of the following is the most common source of infection in vertebral osteomyelitis:
a. Trauma
b. Iatrogenic
c. Hematogenous spread
d. Spontaneous
e. Unknown mechanism
Answers
1. d
The extensor hallucis longus is innervated by L5; weakness of this muscle would be evidence of an L5 radiculopathy.
2. c
Spondylolysis is believed to be a stress or fatigue fracture of the pars interarticularis occurring because of repetitive shear stresses from repetitive hyperextension in individuals with a hereditary predisposition. It occurs most commonly at L5, is more common in boys than in girls and in athletes, particularly gymnasts.
3. d
Urinary retention results from lower motor neuron bladder dysfunction seen in cauda equina compression (CEC) syndrome. Patients with CEC syndrome may also present with severe back pain, saddle anesthesia, pain down the back of lower extremities, or even foot drop, but the most typical and most important manifestation is bladder dysfunction.
4. e
A sequestered herniation is a separation of a herniated fragment from the disk from which it came.
5. c
Sexual dysfunction is a common condition after extensive anterior lumbar surgical dissection. Erectile dysfunction is often nonorganic but may be related to parasympathetic injury. The parasympathetic nerves are deep in the pelvis at the level of S2-S3 and S3-S4 and are not usually involved in the surgical field for anterior L4-L5 and L5-S1 procedures. Retrograde ejaculation is the result of injury to the sympathetic chain on the anterior surface of the major vessels crossing the L4-L5 level and at the L5-S1 interspace. Erectile function and orgasm are not affected by sympathetic injury. The pudendal nerve is primarily a somatic nerve and is not located in the surgical field.
6. e
Aminoglycosides, such as tobramycin, are active against gram-negative organisms. First- and second-generation cephalosporins are alternatives to semisynthetic penicillins that may be useful if the organism is not resistant. Ciprofloxicin has also been considered a possible alternative to penicillins against gram-positive vertebral osteomyelitis.7. c
Hematogenous seeding from another primary source is the most common causative agent. Hematogenous spread of infections is believed to affect the spine via septic emboli in the endarteriolar circulation of segmental spinal arteries at the vertebral endplates. The majority of cases of pyogenic spondylitis begin in the subchondral, metaphyseal region of the anterior subligamentous portion of the vertebral body — the portion with the greatest arterial supply and the most anastomoses.
