NEUROSURGERY PREPARING AND SELF ASSESSMENT MCQs WITH ANSWER

Approximately what percentage of encephaloceles in newborns are occipital? 

1. 40.00% 
2. 70.00% 
3.  85.00% 
4.  55.00% 
5.  25.00%

ANSWER Approximately 85% of encephaloceles are occipital. Encephaloceles develop due to restricted closure of the anterior neural tube (day 24 of gestation). About 50% are associated with hydrocephalus

Which cochlear nucleus responds to high-frequency sound? 

1.  Ventral cochlear nucleus 
2.  Lateral cochlear nucleus 
3.  Intermediate cochlear nucleus 
4.  Medial cochlear nucleus 
5.  Dorsal cochlear nucleus

ANSWER Medial cochlear nucleus The cochlear nucleus is organized such that the dorsal portion is responsible for high frequencies and the ventral part is responsible for low frequencies.

You are performing radiosurgery on a patient with left medically refractory, lancinating ear and throat pain triggered by eating and drinking. Which figure shows the most optimal location of the radiation target? 

1. Figure 1 
2. Figure 2 
3. Figure 3 
4. Figure 4 
5. Figure 5

ANSWER Answer: Figure 2. This patient has glossopharyngeal neuralgia. One treatment option for this patient is stereotactic radiosurgery if medications are ineffective. The best place to place the shot is along the course of the glossopharyngeal nerve, which is seen in Figure 2. A typical dose would be a single 4 mm shot using 80 Gy to the 100% isodose line. Figure 1 shows CN III. Figure 3 shows CN V. Figure 4 shows CN XII. Figure 5 shows CN VIl.

Which of the following nerves enters the orbit outside the common tendinous ring (Annulus of Zinn)?

1.  Oculomotor 
2. Nasociliary 
3. Abducens 
4. Optic 
5. Trochlear

ANSWER Answer : The trochlear nerve The trochlear nerve exits the superior orbital fissure and passes above the tendinous ring of the annulus of Zinn. The figure displays the relationship of structures to the annulus of Zinn.The Annulus of Zinn contains CN II. Ill. VI, the Nasociliary branch of V1.

Which cranial nerve exits the skull through pars nervosa of the jugular foramen? 

1. CN VIII 
2. CN IX 
3. CN X 
4. CN XI 
5. CN XII

ANSWER 2. CN IX

A patient experiences deltoid muscle weakness and neck pain radiating down the lateral upper arm. Which radiculopathy does the patient likely have? 

1. C5 
2. C6 
3. C7 
4. C8 
5. T1

ANSWER Answer: C5 :C5 radiculopathy results in deltoid muscle weakness, anterior upper arm sensory loss and neck pain radiating down the lateral upper arm. While there may be overlap in the muscle groups affected and the distribution of sensory changes and pain syndromes, the involved nerve root can usually be gleaned from the assessment of the overall pattern of involvement. In general, pain occurs in the same dermatomal distribution as the observed sensory changes. Some general patterns of impairment are summarized below.

An 80-year-old female falls, striking her forehead on the ground. On examination, she displays 2/5 bilateral upper extremity strength and 4+/5 bilateral lower extremity strength. Reflexes are diminished, and sensation is decreased to light touch in the bilateral upper extremities. What is the most likely diagnosis? 

1. Anterior cord syndrome 
2. Posterior cord syndrome 
3. Central cord syndrome 
4. Brown-Sequard syndrome 
5. Lateral cord syndrome

ANSWER Central cord syndrome This patient is experiencing central cord syndrome. This syndrome is usually a result of acute hyperextension injury in older patients in the presence of osteophytic spurs and redundant ligamentum flavum. The damage most often occurs with a blow to the upper face or forehead as occurred in this patient after falling forward and hitting the ground. The syndrome is thought to result from edema within the vascular watershed zone in the central region of the cord; The sensory disturbance is more variable and is present below the level of the lesion. Anterior cord syndrome is often secondary to a dislocated bone fragment or traumatic disk herniation resulting in anterior cord compression or occlusion of the anterior spinal artery. This presents with loss of motor, pain, and temperature below the level of the lesion and preservation of dorsal column functions. Posterior cord syndrome, which is relatively rare is due to selective injury or ischemia to the dorsal columns and produces pain and burning Paresthesias in the torso, upper extremities, and neck. Mild weakness of the upper extremities can also occur. Brown-Sequard syndrome is also referred to as spinal cord hemisection and is usually secondary to penetrating rather than blunt trauma. The findings include ipsilateral motor paralysis and loss of dorsal column functions below the level of the lesion and contralateral loss of pain and temperature sensation 1-2segments below the lesion. Brown-Sequard syndrome is also referred to as lateral cord syndrome.

A patient experiences intrinsic hand muscle weakness and ulnar forearm and fifth digit sensory loss. Which radiculopathy does the patient likely have? 

1. C5 
2. C6 
3. C7 
4. C8 
5. T1

ANSWER C8 radiculopathy results in intrinsic hand muscle weakness, ulnar forearm and fifth digit sensory loss, and neck pain radiating along the ulnar forearm to the fourth and fifth digits. Because of the mixed innervation of many of the intrinsic muscles of the hand by C7, C8, and T1, it can often be difficult to differentiate radiculopathy based on the specific pattern of muscular involvement. C8 radiculopathy can be marked by weakness in the flexor carpi ulnar and in the ulnar component of the flexor digitorum profundus. While there may be overlap in the muscle groups affected and the distribution of sensory changes and pain syndromes, the involved nerve root can usually be gleaned from the assessment of the overall pattern of involvement. In general, pain occurs in the same dermatomal distribution as the observed sensory changes.

Which of the following groups of muscles are innervated by the dorsal scapular nerve? 

1. Pectoralis minor, Pectoralis major 
2. Rhomboid major, Rhomboid minor 
3. Serratus anterior, subclavius 
4. Subscapularis, Teres major 
5. Teres minor, Latissimus dorsi

ANSWER Rhomboid major, Rhomboid minor The rhomboid major and rhomboid minor muscles are consistently innervated by the dorsal scapular nerve. The dorsal scapular nerve can also, provide partial innervation to the levator scapulae as it passes underneath this muscle; the primary innervation for levator scapulae is from the cervical plexus (C3 and C4). The rhomboids adduct the scapula Inwards midline) and rotate the scapula downward. Injury to this nerve can result in interscapular wasting and mild scapular winging at rest due to unopposed action of the serratus anterior.

Which of the following muscles is solely innervated by the median nerve? 

1. Abductor pollicis longus 
2. Flexor digitorum profundus 
3. Flexor pollicis longus 
4. Third and fourth lumbricals 
5. Adductor pollicis

ANSWER Flexor digitorum profundus

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Which of the following muscles is innervated solely by the ulnar nerve? 

1. Flexor carpi radialis 
2. Flexor digitorum superficialis 
3. Dorsal Interossei 
4. First and second lumbricals 
5. Flexor pollicis brevis

ANSWER Dorsal Interossei

Which type of muscle fiber primarily derives its energy from anaerobic metabolism? 

1. Skeletal Type I 
2. Skeletal Type II 
3. Cardiac 
4. Smooth muscle

ANSWER Skeletal Type II

Nerve conduction velocity is directly proportional to which of the following? 

1. Number of Ranvier nodes 
2. Capacitance 
3. Membrane resistance 
4. Fiber diameter 
5. Fiber length

ANSWER Fiber length An increase in fiber diameter results in an increase in nerve conduction velocity due to decreased membrane resistance. Capacitance is inversely proportional to the degree of myelination, and therefore an increase in capacitance leads to decreased conduction velocity. The length of the fiber affects the latency, but not the velocity of conduction across a nerve. Nodes of Ranvier exist between myelinated segments and are the site of action potential regeneration. Conduction is faster across myelinated segments than at the nodes. Therefore, an increase in the number of nodes decreases the conduction velocity.

Which ionic equilibrium potential primarily contributes to the resting membrane potential of neurons? 

1. CI 
2. K+ 
3. Mg2+ 
4. Na 
5. Ca2+

ANSWER K+ The resting membrane potential in the equilibrium governs neuron the potential of potassium, which has the highest membrane permeability at rest. The Nernst equation determines the resting membrane potential of an ion based on its intracellular (Ci) and extracellular concentrations (Co): E= +61 log Ci/Co. The sodium equilibrium potential is the most important determinant of the amplitude of the action potential. The chloride potential is the most important determinant of the hyperpolarization potential. Magnesium and calcium have little impact on the resting membrane potential but are integral for synaptic transmission.

All of the following are features of apoptosis EXCEPT: 

1. cell shrinkage 
2. chromatin condensation 
3. cellular fragmentation phagocytosis 
4. cytoplasm swelling

ANSWER cytoplasm swelling Apoptosis leads to nuclear condensation and collapse, blobbing of the membrane with cellular fragmentation, and phagocytosis of remnants. It is related to the binding of ligand to the receptor (CD95) in the extrinsic pathway and an internal oxidative cytochrome-C mediated process. Both internal and external pathways activate a cascade of intracellular enzymes (caspases). Necrosis results in rapid lysis of the membrane and cell without triggering phagocytosis. Ischemia produces necrosis. Hypoxia can produce both apoptosis and necrosis.

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