Nerve Injuries MCQs

Explanation: Neuropraxia is the mildest form of peripheral nerve injury , as described in Seddon's classification . In this condition, the axon remains intact, but there is focal demyelination or damage to the myelin sheath due to compression or ischemia. Conduction block occurs across the site of injury, leading to weakness or sensory loss. Since the axon and endoneurial tubes are preserved, full recovery occurs within weeks to months without Wallerian degeneration. Explanation of other options: Damaged axon, intact nerve sheath (Option B): Describes axonotmesis , where axons are damaged but connective tissue sheaths remain intact. Damaged axon and nerve sheath (Option C): Describes neurotmesis , the most severe form of injury, with a poor prognosis.

Ans.C . Sensitivity to hypoxia is C>B>A Type C fibers (Type IV Lloyd & Hunt) are least susceptible to hypoxia'

Indications of external fixator Open fracture (grade 3b-3c- absolute indication, grade-2-3a-relative indication) Vascular injury Severe soft tissue injury Damage control orthopedics Nerve injury is not an indication of external fixation Reference- AO manual of principle of fracture management

CTS is associated with Colles fracture and not Smith's fracture. Most of the CTS is idiopathic, however there are several risk factors such as: Hypothyroidism Diabetes Acromegaly Rheumatoid arthritis Pregnancy Gout Alcoholism Amyloidosis Sarcoidosis Malunited Colles fracture Reference: J. Maheshwari's 5th Edition of Essential Orthopaedics page no. 114

Carpal tunnel syndrome is produced by entrapment of median nerve beneath the flexor retinaculum. Associated conditions that can leads to carpal tunnel syndrome are: Idiopathic(most common) Pregnancy Endocrine disorders - Hypothyroidism, Diabetes mellitus, Myxedema, Acromegaly, Hyperparathyroidism Deposition disorders - Rheumatoid disorder, Gout, Rheumatic disorder, Amyloidosis, Sarcoidosis, Leukemia, Chronic renal failure Reference: Apley's system of orthopedics & fracture, 8th edition, Page: 247-248.

Wartenberg sign is persistent abduction and extension of the small digit when a patient is asked to adduct the digits and is seen in cubital tunnel syndrome, but not carpal tunnel syndrome. Reference: Maheshwari Essential Orthopedics, 5 th edition, Page no. 303.

Most commonly injured knee ligament is the MCL followed by the ACL. ACL is the most commonly operated knee ligament as most of the MCL injuries are managed conservatively. Reference - Manish Kumar Varshney 1 st edition page no 878

Investigation of choice for knee ligament injury is MRI as it will clearly show injuries of both the cruciates (intra articular) and the collaterals (extra articular) However, the investigation of choice for intra articular knee structures such as, ACL, PCL, menisci and cartilage is diagnostic arthroscopy. This is because, when we put an arthroscope in the knee joint, we can visualize the intra articular structures in 5 to 10 times magnification. Reference - Maheshwari, Essential Orthopedics 5 th edition page no 151.