Question 1

The natural history of an asymptomatic thoracic disk herniation is:

Explanation

The natural history of an asymptomatic thoracic disk herniation is to remain asymptomatic and exhibit little change in size. In a series of 48 asymptomatic thoracic disk herniations, Wood found that all disks remained asymptomatic at follow-up with little fluctuation in size of the disk.

Question 2

A 48-year-old man presents with acute onset of unilateral, anterior band-like chest pain after lifting heavy machinery at work. The history and physical examination and the magnetic resonance image confirm a T9-T10 thoracic disk herniation. The best initial treatment for this patient is:

Explanation

Brown et al retrospectively reviewed the natural history of symptomatic thoracic disk herniations and found 77% of patients did well with nonsurgical management. The patients returned to their previous level of activity following activity modification and physical therapy.

Question 3

The most common site of a thoracic disk herniation requiring surgery is from levels:

Explanation

T8-T11 is the most common site of disk herniation that requires surgery. A review of 71 patients with 82 thoracic disk herniations undergoing surgery found that 66% of disks were between T8-T11. The most common disk level was T9-T10, which represented 26% of the herniations.C orrect Answer: T8- T11

Question 4

The most common location for a thoracic disk herniation is:

Explanation

The most common locations for a thoracic disk herniation are centrolateral (94%) and lateral (6%). Disks classified as centrolateral have the bulk of the disk herniation medial to the lateral margin of the thecal sac.

Question 5

A 38-year-old construction worker falls from a scaffolding and sustains a pure flexion-compression injury to T12. In this type of injury, which portion of the vertebral body fails first:

Explanation

Failure occurs first at the end plate. The intact intervertebral disk has limited compressibility. Therefore, when the compressive forces exceed the disk compressibility, the load is transmitted to the contiguous bone. The end plate will rupture first followed by the subcortical cancellous vertebral bone.

Question 6

An absolute indication for surgical management of thoracolumbar burst fractures is:

Explanation

Patients with a neurologic deficit or a progressive neurologic deficit should undergo operative decompression. C ontroversy exists as to the amount of kyphosis and canal compression that is considered acceptable. Support can be found in the literature for both operative and nonoperative management of neurologically intact burst fractures. Each patient must be evaluated on a case by case basis and followed closely after injury.

Question 7

A 12-year-old girl presents with back pain of 3 monthsâ duration. She is a Risser stage 2. She displays a left thoracic curve of 27° on radiographs. The next study obtained in the work-up should be:

Explanation

Left thoracic curves are unusual in idiopathic scoliosis. A magnetic resonance image of the thoracic spine is mandatory in the work-up to rule out diastematomyelia, tethered spinal cord, spinal tumor, or other type of congenital anomaly.

Question 8

The most common organism responsible for vertebral column infection is:

Explanation

Staphylococcus aureus accounts for more than 50% of spinal infections and often results from hematogenous dissemination. Gram-negative organisms are more common following genitourinary procedures or urinary tract infections. Staphylococcus epidermidis can complicate spinal surgical wounds, and polymicrobial infection is more common in these circumstances.

Question 9

Symptoms of spinal infection may include all of the following except:

Explanation

Neck or back pain associated with spinal infection is relentless and constant. The pain is not usually associated with activity. There may be night pain as well. Other symptoms and signs are variable, requiring a high degree of suspicion. Fever occurs less than 50% of the time and neurological deficit less than 10% of the time. Paraspinal muscle spasms may result in decreased range of motion or torticollis.

Question 10

Which test is most specific for diagnosing spinal column infection:

Explanation

Vertebral biopsy, either via open or computed tomography-guided means, is most specific even though false-negative rates for closed and open biopsies are 30% and 14%, respectively. A patients white blood count may be normal even in acute spinal infection. Although often elevated, erythrocyte sedimentation rate and carbon-reactive protein are nonspecific tests. Blood cultures are negative in more than 75% of patients.

Question 11

Which of the following describes the magnetic resonance image (MRI) appearance of vertebral osteomyelitis:

Explanation

Magnetic resonance image (MRI) carries a 95% accuracy rate. Infected disk and vertebral bone appear on MRI with decreased signal onT1 images and increased signal on T2 images. Gadoliniun enhancement is useful in differentiating spinal infection or abscess from epidural scar in the postoperative setting.

Question 12

Appropriate treatment for spinal infection may include all the following except:

Explanation

Spinal stability appears to improve healing of spinal infection. C hronic, persistent infections may require removal of hardware. Antibiotics and immobilization are the mainstays of treatment. Neurological deficit from epidural abscess or kyphotic collapse may require operative decompression.

Question 13

Which of the following is not a surgical indication in the treatment of spinal column infection:

Explanation

Uncomplicated spinal osteomyelitis and diskitis are treated nonoperatively. Operative debridement, decompression, and stabilization may be useful in cases of abscess, sepsis, neurological deficit, and progressive deformity.

Question 14

Which of the following is more characteristic of tuberculoid rather than pyogenic spinal infection:

Explanation

Spinal tuberculosis typically follows an indolent course early on despite radioqraphic findings out of proportion to the exam. Pyogenic and tuberculoid spinal infections involve the thoracic spine more commonly than the cervical spine. Both spinal infections may result in bony destruction, elevated erythrocyte sedimentation rates, and may or may not present with constitutional symptoms.

Question 15

Which of the following is a risk factor for neurological deficit associated with tuberculoid spinal infection:

Explanation

Tuberculosis in the cervical spine of children younger than 10 years of age carries a significantly lower risk of paralysis than in older patients (17% vs 81%).

Question 16

All of the following organisms may cause granulomatous opportunistic spinal infection in immunocompromised patients except:

Explanation

Staphylococcal infection is typically pyogenic, not granulomatous.

Question 17

Antibiotic treatment for spinal tuberculosis includes all of the following except:

Explanation

A four-drug regimen against spinal tuberculosis is recommended because of the high prevalence of organism resistance. Cefotaxime is a cephalosporin not active against mycobacterial infection.

Question 18

What percentage of spinal infections have concurrent positive blood cultures:

Explanation

Even though the majority of spinal infections are considered hematogenous in origin, only 25% of infections occur with positive blood cultures.

Question 19

The treatment of choice for spinal epidural abscess is:

Explanation

It is generally believed that pockets of pus, whether they are epidural, paravertebral, or psoas abscesses, must be drained in addition to antimicrobial therapy.

Question 20

Which of the following antibiotics would not be useful in staphylococcal vertebral osteomyelitis:

Explanation

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.

Question 21

Which surgical approach is absolutely contraindicated for a massive, calcified, central thoracic disk herniation causing myelopathy?

Explanation

Standard laminectomy is contraindicated for central thoracic disc herniations due to the high risk of catastrophic spinal cord injury. The thoracic cord does not tolerate retraction, and the kyphotic alignment drapes the cord over the anterior compressive lesion.

Question 22

The Artery of Adamkiewicz, which provides major blood supply to the anterior lower two-thirds of the spinal cord, most commonly arises from which region?

Explanation

The Artery of Adamkiewicz usually originates on the left side between T8 and L1 in approximately 70-80% of individuals. Injury to this vessel during anterior thoracic approaches can lead to anterior spinal artery syndrome.

Question 23

A 50-year-old female presents with progressive gait ataxia and lower extremity spasticity. MRI reveals a large central calcified thoracic disc herniation at T10-T11. What is the most appropriate surgical approach?

Explanation

A transthoracic approach allows direct visualization and removal of anterior central calcified discs without manipulating the spinal cord. Laminectomy and posterior interlaminar approaches risk cord injury due to required retraction.

Question 24

Pediatric thoracic disc calcifications are often discovered incidentally or present with localized back pain. What is the most appropriate management for a neurologically intact child with a symptomatic calcified thoracic disc?

Explanation

Pediatric thoracic disc calcifications are usually self-limiting and tend to resorb over time. Conservative management is the treatment of choice in the absence of neurological deficits.

Question 25

During a right-sided transthoracic approach for a T4-T5 disc herniation, the surgeon injures a longitudinal neural structure running along the heads of the ribs. What is the most likely clinical consequence of this injury?

Explanation

The sympathetic chain runs longitudinally along the rib heads in the upper thoracic spine. Injury to the chain in the upper thoracic region (T1-T4) can result in ipsilateral Horner's syndrome (ptosis, miosis, anhidrosis).

Question 26

A 55-year-old man undergoes a costotransversectomy for a T8-T9 paracentral disc herniation. Postoperatively, he develops a pleural effusion, and fluid analysis reveals high triglyceride levels and lymphocytes. Which structure was most likely injured?

Explanation

A chylothorax results from injury to the thoracic duct, characterized by milky pleural fluid high in triglycerides. The thoracic duct typically ascends on the right side of the lower thoracic spine and crosses to the left around T4-T5.

Question 27

When performing a transpedicular approach for a thoracic disc herniation, which of the following boundaries must be removed to access the disc space safely?

Explanation

The transpedicular approach involves removal of the facet joint and the pedicle to access the lateral aspect of the disc space and the ventral spinal canal. This approach is best for lateral or foraminal disc herniations.

Question 28

Which of the following physical examination findings is most specific for thoracic myelopathy rather than a lumbar pathology?

Explanation

Upper motor neuron signs such as hyperreflexia, spasticity, and a positive Babinski sign differentiate spinal cord compression (thoracic or cervical myelopathy) from lower motor neuron lumbar pathology.

Question 29

In a patient presenting with an isolated band-like chest pain radiating horizontally around the thorax, which condition must be ruled out before diagnosing a thoracic radiculopathy from a disc herniation?

Explanation

Herpes zoster (shingles) frequently presents with intense, radicular band-like pain in a thoracic dermatome before the appearance of the classic vesicular rash, mimicking a thoracic disc herniation.

Question 30

What is the primary advantage of the video-assisted thoracoscopic surgery (VATS) approach over an open thoracotomy for thoracic disc herniations?

Explanation

VATS is minimally invasive and avoids the significant morbidity of a thoracotomy, including rib retraction, thereby reducing postoperative pain and improving pulmonary recovery.

Question 31

A 45-year-old patient with an acute T7-T8 disc herniation presents with profound weakness of the right leg, loss of proprioception in the right leg, and loss of pain and temperature sensation in the left leg. This clinical picture is most consistent with:

Explanation

Brown-Séquard syndrome results from hemisection of the spinal cord, causing ipsilateral motor and dorsal column deficits (proprioception) and contralateral spinothalamic deficits (pain/temperature).

Question 32

A surgeon is evaluating a patient with a paracentral, non-calcified thoracic disc herniation at T6-T7 causing radicular pain but no myelopathy. The patient failed 6 months of conservative therapy. What is the most appropriate next step?

Explanation

For a lateral or paracentral soft disc herniation, posterior-lateral approaches (transpedicular or costotransversectomy) provide excellent access without the morbidity of an anterior approach or the dangers of laminectomy.

Question 33

When repairing an incidental dural tear during an anterior transthoracic approach for a disc herniation, which of the following techniques is most commonly utilized if primary closure is impossible?

Explanation

Inaccessible anterior dural tears are managed with onlay grafts (muscle, fat, fascia) combined with sealants. Dural tears draining into the pleural space can lead to pleural effusions and require meticulous closure.

Question 34

Intraoperative neuromonitoring (IONM) during thoracic disc surgery typically includes Somatosensory Evoked Potentials (SSEPs) and Motor Evoked Potentials (MEPs). Which specific complication is MEP monitoring best suited to detect early during anterior approaches?

Explanation

MEPs monitor the anterior and lateral corticospinal tracts, which are supplied by the anterior spinal artery. They are highly sensitive to ischemic changes in the anterior spinal cord, which SSEPs might miss.

Question 35

A 60-year-old male with a history of prostate cancer presents with a T10 vertebral body collapse and a retropulsed fragment causing acute myelopathy. While differentiating this from a simple thoracic disc herniation, which MRI sequence is most helpful to distinguish tumor from benign osteoporotic collapse?

Explanation

DWI and Apparent Diffusion Coefficient (ADC) maps are highly specific for differentiating malignant from benign vertebral compression fractures. Malignant lesions typically show restricted diffusion.

Question 36

Thoracic disc herniations represent approximately what percentage of all symptomatic spinal disc herniations?

Explanation

Symptomatic thoracic disc herniations are rare, accounting for less than 1% of all herniated discs requiring surgery. This is partly due to the stability provided by the rigid rib cage.

Question 37

Which of the following features on MRI indicates a worse prognosis for recovery following decompression of a thoracic disc herniation causing myelopathy?

Explanation

T1 hypointensity in the spinal cord indicates myelomalacia and cystic necrosis, which are irreversible structural changes. T2 hyperintensity alone may reflect edema and has a better prognosis.

Question 38

The "safe zone" for inserting a pedicle screw in the mid-thoracic spine is limited medially by the spinal cord and laterally by the:

Explanation

The lateral boundary of the thoracic pedicle is the lateral cortex of the pedicle, bordered immediately by the costovertebral joint and the rib head.

Question 39

What is the anatomical rationale for utilizing a right-sided thoracotomy approach rather than a left-sided approach for a central T7-T8 disc herniation?

Explanation

A right-sided thoracotomy is often preferred in the mid-to-lower thoracic spine to avoid the descending aorta, which is situated predominantly on the left side of the vertebral column.

Question 40

A patient undergoes an anterior thoracic discectomy at T9-T10. Postoperatively, the patient develops a unilateral, segmental, severe neuropathic pain along the 9th rib. Which intraoperative action most likely caused this?

Explanation

Intercostal neuralgia is a known complication of transthoracic approaches, resulting from direct trauma, excessive retraction, or entrapment of the intercostal nerve during rib resection or chest closure.

Question 41

A 55-year-old male presents with progressive spastic paraparesis and hyperreflexia. Magnetic resonance imaging demonstrates a large, calcified, central thoracic disk herniation at T8-T9 causing severe cord compression. Which of the following surgical approaches is contraindicated?

Explanation

A standard posterior laminectomy is strictly contraindicated for central, calcified thoracic disk herniations. Removing posterior elements allows the spinal cord to bowstring posteriorly over the anterior mass, creating an unacceptably high risk of catastrophic iatrogenic spinal cord injury.

Question 42

When planning an anterior thoracotomy for a left-sided T9-T10 disc herniation, the surgeon must be mindful of the artery of Adamkiewicz to prevent anterior spinal artery syndrome. At what level and side does this radiculomedullary artery most commonly originate?

Explanation

The artery of Adamkiewicz provides the major arterial supply to the lower two-thirds of the spinal cord. It most commonly arises from the left side of the aorta between the T9 and L1 levels in approximately 75% of patients.

Question 43

A 45-year-old female undergoes an anterior transthoracic discectomy at the T1-T2 level. Postoperatively, she is noted to have unilateral ptosis, miosis, and anhidrosis on the ipsilateral side. Which structure was most likely compromised during the exposure?

Explanation

The clinical presentation describes Horner's syndrome, caused by disruption of the sympathetic chain. During upper thoracic anterior approaches, the stellate ganglion, located anterior to the neck of the first rib, is at high risk of iatrogenic injury.

Question 44

A patient presents with a right-sided paracentral T7-T8 disk herniation leading to Brown-Sequard syndrome. Which of the following neurological findings is expected below the level of the lesion?

Explanation

Brown-Sequard syndrome (hemicord syndrome) results in ipsilateral loss of motor function (corticospinal tract) and proprioception/vibration (dorsal columns). It also causes contralateral loss of pain and temperature sensation (spinothalamic tract).

Question 45

Which of the following is considered a distinct advantage of a costotransversectomy approach compared to an anterior transthoracic approach for the excision of a lateral thoracic disc herniation?

Explanation

Costotransversectomy allows posterolateral access to the thoracic spine without entering the pleural cavity, reducing pulmonary complications and the need for chest tubes. However, it provides limited visualization across the midline compared to an anterior transthoracic approach.

Question 46

The classic Sorensen radiographic criteria for the diagnosis of Scheuermann's kyphosis require which of the following findings?

Explanation

Sorensen criteria define Scheuermann's kyphosis strictly as anterior wedging of greater than 5 degrees in at least three consecutive vertebral bodies. Endplate irregularities and Schmorl's nodes are supportive findings but are not required for diagnosis.

Question 47

In a 14-year-old patient diagnosed with Scheuermann's kyphosis, which of the following scenarios is the most appropriate indication for initiating treatment with a Milwaukee brace?

Explanation

Extension bracing is indicated for skeletally immature patients presenting with a kyphotic curve between 50 and 75 degrees. Curves exceeding 75 degrees often require surgical correction, while mature patients or mild curves are managed symptomatically.

Question 48

To minimize the risk of ischemic spinal cord injury during a left-sided thoracotomy for a T8 corpectomy, how should the segmental vessels be managed?

Explanation

Segmental vessels should be ligated unilaterally at the mid-vertebral body rather than near the neural foramen. This preserves critical collateral anastomotic flow within the neural foramen, thereby reducing the risk of spinal cord ischemia.

Question 49

A 35-year-old female complains of diffuse, glove-like numbness in both upper extremities accompanied by mid-thoracic back pain. Electromyography and cervical MRI are completely normal. A diagnostic sympathetic block at the upper thoracic level provides immediate and complete relief of her symptoms. What is the most likely diagnosis?

Explanation

T4 syndrome is a clinical condition characterized by upper extremity paresthesias (often non-dermatomal or glove-like) and sympathetic symptoms driven by upper thoracic spine dysfunction. It is often successfully managed with manual mobilization or sympathetic blocks.

Question 50

A 65-year-old male is incidentally noted to have flowing ossification along the anterolateral aspect of his thoracic spine. According to the Resnick criteria, which of the following is required to establish a diagnosis of Diffuse Idiopathic Skeletal Hyperostosis (DISH)?

Explanation

The Resnick criteria for DISH require the presence of flowing ossification over at least four contiguous vertebral bodies and preservation of intervertebral disc height. Additionally, there must be an absence of apophyseal joint ankylosis and sacroiliac joint erosion.

Question 51

A 25-year-old male sustains a T12 Chance fracture following a high-speed motor vehicle collision while wearing a lap belt. What associated injury must be urgently ruled out during his initial trauma evaluation?

Explanation

Chance fractures are flexion-distraction injuries highly associated with lap seatbelt use. There is a high incidence (up to 50%) of concomitant intra-abdominal injuries, particularly hollow viscus ruptures, which must be immediately excluded.

Question 52

A 40-year-old recent immigrant presents with severe back pain, fevers, and a progressive gibbus deformity. Imaging reveals severe osteolysis of the T8 and T9 anterior vertebral bodies with relative preservation of the intervening intervertebral disc space. What is the most likely responsible pathogen?

Explanation

Mycobacterium tuberculosis (Pott's disease) characteristically destroys the anterior vertebral bodies leading to collapse and a sharp kyphosis (gibbus deformity). Unlike pyogenic infections, tuberculous spondylitis typically spares or shows delayed destruction of the intervertebral disc space.

Question 53

Ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine most commonly presents with slowly progressive myelopathy and is most prevalent in which of the following patient demographics?

Explanation

While cervical OPLL is slightly more common in East Asian males, thoracic OPLL is classically more prevalent in Japanese females. It is a known cause of severe, progressive thoracic myelopathy.

Question 54

A 30-year-old patient falls from a height, sustaining a T11 burst fracture with 60% canal compromise. The patient is neurologically intact, and MRI confirms an intact posterior ligamentous complex. What is the most appropriate management plan?

Explanation

In a neurologically intact patient with a mechanically stable burst fracture (indicated by an intact posterior ligamentous complex), non-operative management with a TLSO is indicated. Significant spontaneous spinal canal remodeling typically occurs over time.

Question 55

When placing pedicle screws in the thoracic spine, knowledge of normal morphometry is crucial. At which of the following thoracic levels are the pedicles typically the narrowest in their transverse dimension?

Explanation

The transverse pedicle diameter in the thoracic spine is generally narrowest in the mid-thoracic region, specifically around T4 to T6. This makes pedicle screw placement at these levels technically demanding and carries a higher risk of pedicle breach.

Question 56

A patient undergoes a transforaminal epidural steroid injection for a right T10 radiculopathy. Immediately post-procedure, the patient develops profound bilateral lower extremity flaccid paralysis and loss of pain sensation, but proprioception is preserved. What is the most likely etiology of this complication?

Explanation

The clinical presentation indicates anterior spinal artery syndrome. In the context of a thoracic transforaminal injection, this devastating complication is highly suspected to result from a particulate steroid embolus occluding a critical radiculomedullary artery.

Question 57

A 55-year-old male with a history of intravenous drug use presents with severe midthoracic back pain. Gadolinium-enhanced MRI demonstrates epidural enhancement and high T2 signal within the T6-T7 disc space and adjacent endplates. What is the most common organism responsible for this condition?

Explanation

Staphylococcus aureus remains the most common causative organism of pyogenic spinal infections (discitis/osteomyelitis) across all patient groups, including intravenous drug users. Pseudomonas is a notable risk in the IVDU population, but S. aureus is still more frequent.

Question 58

During an initial clinical evaluation, a patient with a known central thoracic disk herniation demonstrates normal upper extremity reflexes but exhibits spastic paraparesis, hyperreflexia in the lower extremities, and absent abdominal reflexes. Based on these reflex findings, the lesion is most likely located above which spinal level?

Explanation

Absent abdominal reflexes, combined with lower extremity upper motor neuron signs, localize the lesion above the lower thoracic segments. The superficial abdominal reflexes are mediated by levels T8 through T12.

Question 59

A 60-year-old patient presents with symptoms of tandem spinal stenosis affecting both the cervical and thoracic regions. Which clinical finding uniquely distinguishes a thoracic myelopathy from a cervical myelopathy?

Explanation

Thoracic myelopathy leads to upper motor neuron signs in the lower extremities while completely sparing the upper extremities. A cervical myelopathy typically involves both upper (Hoffman sign, hyperreflexia) and lower extremity long tract signs.

Question 60

Which of the following is considered the most common initial presenting symptom in a patient with a symptomatic thoracic disk herniation?

Explanation

The vast majority of symptomatic thoracic disk herniations initially present with localized axial back pain. Radicular pain wrapping around the chest wall or myelopathic lower extremity symptoms typically develop later as the herniation enlarges.

Question 61

A 55-year-old man presents with progressive lower extremity weakness and myelopathy. Imaging reveals a large, central, calcified disc herniation at T8-T9 causing severe cord compression. Which of the following is the most appropriate surgical approach?

Explanation

A posterior laminectomy is strongly contraindicated for central thoracic disc herniations due to the high risk of iatrogenic spinal cord injury from medial cord retraction. Anterior or anterolateral approaches (e.g., transthoracic, costotransversectomy) are required to safely safely remove the calcified fragment.

Question 62

During an anterior corpectomy for a T11 burst fracture, the surgeon must be mindful of the vascular supply to the anterior spinal cord. The artery of Adamkiewicz most commonly enters the spinal canal at which of the following locations?

Explanation

The artery of Adamkiewicz (great anterior radiculomedullary artery) provides major blood supply to the lower two-thirds of the spinal cord. It typically arises from a left intercostal or lumbar artery between the levels of T8 and L1.

Question 63

A 62-year-old Asian man presents with signs of progressive thoracic myelopathy. Sagittal CT imaging demonstrates beak-like osseous excrescences projecting anteriorly from the posterior elements at the T10-T11 level. What is the most likely diagnosis?

Explanation

Ossification of the ligamentum flavum (OLF) predominantly affects the lower thoracic spine (T10-T12) and is a well-known cause of thoracic myelopathy. It occurs most frequently in populations of East Asian descent and presents with posterior cord compression.

Question 64

A 15-year-old boy presents with back pain and increasing thoracic kyphosis. Lateral radiographs of the thoracic spine demonstrate distinct anterior wedging of the vertebral bodies. According to the Sorensen criteria, what is required to confirm a diagnosis of Scheuermann kyphosis?

Explanation

The classic Sorensen criteria for diagnosing Scheuermann kyphosis mandate anterior wedging of 5 degrees or more in at least three consecutive vertebral bodies. Associated findings often include Schmorl nodes and irregular vertebral endplates.

Question 65

A 25-year-old man is brought to the trauma bay following a high-speed motor vehicle collision where he was wearing only a lap belt. Radiographs show a transverse fracture through the vertebral body, pedicles, and spinous process of T12. Which of the following is most commonly associated with this injury pattern?

Explanation

A Chance fracture is a flexion-distraction injury typically caused by a lap belt acting as a fulcrum. It is highly associated with concomitant hollow viscus intra-abdominal injuries (up to 50% of cases), requiring careful general surgical evaluation.

Question 66

A 68-year-old man presents with chronic stiffness in his middle and upper back. Radiographs reveal diffuse flowing ossification along the anterolateral aspect of the thoracic spine. To formally diagnose Diffuse Idiopathic Skeletal Hyperostosis (DISH), the Resnick criteria require which of the following?

Explanation

The Resnick criteria for DISH require flowing ossification of the anterior longitudinal ligament across at least four contiguous vertebral bodies. Furthermore, disc heights must be relatively preserved, and there should be an absence of sacroiliac joint sclerosis or fusion.

Question 67

When planning for posterior instrumented fusion of the thoracic spine, pre-operative computed tomography (CT) is utilized to evaluate pedicle morphology. In the normal adult spine, the narrowest pedicle diameters are typically found at which levels?

Explanation

The narrowest pedicle diameters in the thoracic spine are typically located at the T4 to T6 levels. Preoperative CT planning is essential to ensure safe pedicle screw placement and to determine if alternative fixation, such as hooks or extrapedicular screws, is needed.

Question 68

A 50-year-old man with a long-standing history of ankylosing spondylitis falls from a standing height and complains of new mid-back pain. Initial standard radiographs appear unremarkable. What is the most critical consideration regarding his spine pathology?

Explanation

The ankylosed spine behaves mechanically like a long bone; even minor trauma can cause highly unstable, through-and-through fractures (often hyperextension injuries). Advanced imaging (CT/MRI) is mandatory due to a high incidence of occult fractures and associated epidural hematomas.

Question 69

A patient undergoes an anterior approach for the excision of a symptomatic thoracic disc herniation. Post-operatively, the patient is noted to have ipsilateral ptosis, miosis, and anhidrosis. The surgery was most likely performed at which of the following thoracic levels?

Explanation

Anterior surgical approaches to the upper thoracic spine (T1-T2) risk injury to the stellate ganglion or the upper sympathetic chain. This iatrogenic injury results in Horner syndrome, clinically presenting as ptosis, miosis, and anhidrosis.

Question 70

A 58-year-old woman with a history of breast cancer presents with progressive mechanical back pain. MRI shows a metastatic lesion at T8. Her Spinal Instability Neoplastic Score (SINS) is calculated to be 15. What does this score indicate regarding her management?

Explanation

The Spinal Instability Neoplastic Score (SINS) evaluates tumor-related spinal instability. A score between 13 and 18 indicates definite spinal instability, warranting surgical consultation for potential stabilization before or concurrently with oncologic treatment.

Question 71

A 40-year-old immigrant presents with chronic back pain, low-grade fevers, and an increasing gibbus deformity. Imaging demonstrates anterior vertebral body destruction with disc space narrowing. In spinal tuberculosis (Pott disease), what is the most common anatomic location of involvement?

Explanation

Spinal tuberculosis (Pott disease) most commonly affects the lower thoracic and upper lumbar spine (thoracolumbar junction). The infection classically begins in the anterior vertebral metaphysis and spreads under the anterior longitudinal ligament, leading to anterior collapse and gibbus deformity.

Question 72

A 16-year-old boy presents with severe mid-back pain that is worse at night. The pain is consistently relieved by ibuprofen. A CT scan of the thoracic spine is obtained. Based on his likely diagnosis, where is the lesion most commonly located anatomically?

Explanation

Osteoid osteomas of the spine classically present with nocturnal pain that is dramatically relieved by NSAIDs. When occurring in the spine, they are almost exclusively located in the posterior elements (e.g., lamina, pedicle, pars).

Question 73

A 45-year-old man presents with progressive lower extremity weakness and myelopathy. Imaging reveals a large, central, heavily calcified thoracic disc herniation at T8-T9. Why is a standard posterior laminectomy contraindicated in this clinical scenario?

Explanation

Standard posterior laminectomy for central thoracic disc herniations is absolutely contraindicated due to a high rate of catastrophic neurological deterioration. Retraction of the thoracic spinal cord to access a central disc is poorly tolerated due to its limited mobility and tenuous blood supply.

Question 74

A surgeon is planning a left-sided anterior transthoracic approach to decompress a symptomatic T10-T11 disc herniation. Which critical vascular structure is at greatest risk during the exposure on the left side of the lower thoracic spine?

Explanation

The Artery of Adamkiewicz provides the major arterial supply to the lower two-thirds of the spinal cord. It typically originates from the left side between T8 and L1, making it highly vulnerable during left-sided anterior approaches to the lower thoracic spine.

Question 75

What is the most common initial presenting symptom in patients with a symptomatic thoracic disc herniation?

Explanation

Axial thoracic back pain is the most common presenting symptom in patients with thoracic disc herniations. Although myelopathic symptoms or band-like radicular pain often prompt surgical intervention, localized axial pain is frequently the earliest manifestation.

Question 76

Which of the following radiographic characteristics of a thoracic disc herniation is most strongly associated with intradural extension?

Explanation

Disc calcification is strongly associated with intradural extension and dural adherence in thoracic disc herniations. Calcified thoracic discs are often termed "hard discs" and carry a higher risk of dural tears during surgical resection.

Question 77

A 35-year-old woman presents with severe right-sided band-like chest pain radiating along the T7 dermatome. MRI reveals a soft, right-sided far-lateral disc herniation at T7-T8 with no myelopathy. What is the most appropriate surgical approach if conservative measures fail?

Explanation

The posterolateral transpedicular approach is ideal for lateral and foraminal soft thoracic disc herniations. It avoids the morbidity of a transthoracic approach while safely decompressing the nerve root without manipulating the spinal cord.

Question 78

The thoracic spinal cord is particularly vulnerable to ischemic injury due to a vascular "watershed" area. This zone of precarious blood supply is typically located between which vertebral levels?

Explanation

The upper thoracic spine receives blood from the radicular arteries of the neck, and the lower cord from the Artery of Adamkiewicz. The mid-thoracic region (T4-T9) serves as a vascular watershed zone, making it highly susceptible to ischemic insults.

Question 79

A 52-year-old man presents with acute onset of saddle anesthesia, bowel incontinence, and bilateral leg weakness. MRI demonstrates a large, extruded disc herniation. Given the clinical presentation, at which of the following thoracic levels is the herniation most likely located?

Explanation

A herniation at T11-T12 or T12-L1 compresses the conus medullaris, resulting in conus medullaris syndrome. This presents with mixed upper and lower motor neuron signs, saddle anesthesia, and early bowel/bladder dysfunction.

Question 80

Following a right-sided transthoracic approach for a T8-T9 disc herniation, the patient is noted to have an asymmetric umbilicus that deviates upward upon flexing the neck (positive Beevor's sign). What is the most likely cause?

Explanation

Beevor's sign occurs when the lower abdominal muscles are paralyzed, causing the umbilicus to deviate upward during abdominal contraction. This indicates injury or dysfunction of the lower thoracic nerve roots (T10-T12) or, as in this case, selective denervation of the T8/T9 intercostal nerves supplying the rectus abdominis.

Question 81

Which of the following represents an absolute contraindication to Video-Assisted Thoracoscopic Surgery (VATS) for the treatment of a thoracic disc herniation?

Explanation

Extensive pleural adhesions, typically from previous thoracotomy, severe empyema, or pleurodesis, represent an absolute contraindication to VATS. The adhesions prevent safe lung deflation and endoscopic visualization of the spine.

Question 82

Why are clinical thoracic disc herniations significantly less common than those in the cervical and lumbar regions?

Explanation

The splinting effect of the rib cage and the coronal orientation of the facet joints severely limit flexion, extension, and rotation in the thoracic spine. This rigid stabilization dramatically reduces the mechanical stress placed on thoracic intervertebral discs.

Question 83

A patient with a right-sided paracentral disc herniation at T7-T8 develops a Brown-Sequard syndrome. What pattern of neurological deficit is expected on physical examination?

Explanation

Brown-Sequard syndrome involves hemicord compression. It presents with ipsilateral loss of motor function and proprioception (right side), and contralateral loss of pain and temperature sensation (left side) due to the crossover of the spinothalamic tracts.

Question 84

During an anterior transthoracic resection of a heavily calcified T8-T9 disc, an intraoperative dural tear occurs resulting in a cerebrospinal fluid (CSF) leak. What is the most appropriate intraoperative management?

Explanation

Anterior dural tears during thoracic disc surgery should be primarily repaired if possible, often augmented with a fascial or muscle patch and fibrin glue. Placing a chest tube on high suction is contraindicated as it can exacerbate the fistula and cause intracranial hypotension.

Question 85

Within the thoracic spinal canal, what is the most common anatomical location for a symptomatic disc herniation to occur?

Explanation

Unlike lumbar disc herniations, which are typically posterolateral, approximately 75% of symptomatic thoracic disc herniations occur in the central or paracentral location. This directly contributes to their high propensity for causing myelopathy.

Question 86

What anatomical feature of the thoracic spinal canal contributes significantly to the high risk of myelopathy from a central disc herniation?

Explanation

The thoracic spinal canal is circular and has a very high cord-to-canal ratio, meaning the spinal cord occupies most of the available space. This "tight fit" leaves minimal reserve capacity, allowing even small disc herniations to cause significant cord compression.

Question 87

In the surgical planning for thoracic disc herniations, a "giant" thoracic disc is typically defined as one that occupies what percentage of the spinal canal cross-sectional area?

Explanation

A giant thoracic disc herniation is classically defined in the literature as one that occupies greater than 40% of the spinal canal volume. These lesions are technically demanding to resect and carry a higher risk of perioperative neurological injury.

Question 88

A 42-year-old man is diagnosed with a symptomatic T1-T2 thoracic disc herniation. In addition to radicular pain, which of the following autonomic findings is most likely to be present on physical examination?

Explanation

A T1-T2 disc herniation can compress the T1 sympathetic roots. This disruption of the sympathetic chain can result in an ipsilateral Horner's syndrome, characterized by ptosis, miosis, and anhidrosis.

Question 89

Which of the following is a recognized advantage of the lateral extracavitary approach over the anterior transthoracic approach for the treatment of a thoracic disc herniation?

Explanation

The lateral extracavitary approach provides ventral access to the thecal sac without breaching the pleura, thereby avoiding chest tubes and decreasing pulmonary complications. However, it is a highly morbid posterior exposure that disrupts the posterior tension band.

Question 90

Thoracic disc herniations in the adolescent population are most frequently associated with which underlying spinal pathology?

Explanation

Adolescent thoracic disc herniations are relatively rare but are highly associated with Scheuermann's kyphosis. The altered biomechanics and vertebral endplate irregularities (Schmorl's nodes) predispose these patients to disc herniations.

Question 91

A 55-year-old asymptomatic woman undergoes an MRI of the thoracic spine for a research study. Based on current epidemiological data, what is the approximate probability of finding an incidental, asymptomatic thoracic disc herniation?

Explanation

MRI studies of asymptomatic volunteers reveal a high prevalence of incidental thoracic disc herniations, generally reported between 30% and 40%. The vast majority of these lesions remain completely asymptomatic and follow a benign natural history.

Question 92

A patient with a central T6-T7 disc herniation exhibits severe myelopathy. During a physical examination to distinguish this from cervical myelopathy, which of the following findings would specifically point toward a thoracic etiology?

Explanation

A thoracic lesion causes upper motor neuron signs (hyperreflexia, spasticity) exclusively in the lower extremities. The upper extremities remain neurologically intact, which helps clinically differentiate thoracic myelopathy from cervical myelopathy.

Orthopedic Prometric MCQs - Chapter 3 Part 1

Orthopedic Prometric MCQs - Chapter 3 Part 25

Orthopedic Prometric MCQs - Chapter 3 Part 25

Chapter Index