CENTRAL NERVOUS SYSTEM

Question 1

1. Which of the following statements are correct about Thyroglossal duct cyst:
   (a) Is usually located the level of or immediately below the hyoid bone.
   (b) Accounts for 70 % of all congenital neck anomalies.
   (c) Is usually located in the midline.
   (d) Typically presents as a painful neck lump.
   (e) During embryological development, the thyroid gland migrates down behind the hyoid bone.

Answer 1

Answers:
(a) Correct
(b) Correct
(c) Correct
(d) Not correct
(e) Not correct
Explanation:
The thyroid is gland begins to develop in the third week of gestation as a median outgrowth from the floor of the
primitive pharynx at the level of foramen Caecum which lies at the junction of the anterior two thirds and posterior
third of the tongue.
It descends down on the floor of the mouth, anterior to the hyoid bone, to each its final position in the inferior part of
the neck by 7th week of gestation.
It typically presents as a painless lump. A painful lump can occur if there is imposed infection.

Question 2

2. The following skull foramina transmit the named cranial nerves:
   (a) Superior orbital fissure –VIth cranial nerve.
   (b) Foramen ovale – orbital division of Vth cranial nerve
   (c) Inferior orbital fissure – IIIrd cranial nerve.
   (d) Internal auditory meatus – VIIth cranial nerve.
   (e) Foramen rotundum – maxillary division of Vth cranial nerve.

Answer 2

Answers:
(a) Correct
(b) Not correct
(c) Not correct
(d) Correct
(e) Correct
Explanation:
The inferior orbital fissure transmits the infraorbital nerve (i.e. continuation of the second division of the fifth cranial
nerve) and emissary veins that drain the inferior ophthalmic vein to the pterygoid plexus.
The foramen ovale transmits the mandibular division of fifth cranial nerve and the accessory meningeal artery.
The internal auditory meatus contains the seventh and eighth cranial nerves as well as the internal auditory artery.

Question 3

3. Which of the following statements are correct about Haemangioblastoma (HB):
   (a) The most common site is the spinal cord.
   (b) Is the most common primary cerebellar tumor in adults.
   (c) Most patients with multiple HBs have von Hippel-Lindau disease
   (d) Most HBs have homogeneously solid appearance on MRI.
   (e) Most HBs do not enhance after intravenous gadolinium

Answer 3

Answers:
(a) Not correct
(b) Correct
(c) Correct
(d) Not correct
(e) Not correct
Explanation:
HB is a vascular tumour of the CNS. It occurs most often in the cerebellum, where it is the most common primary
neoplasm in adults. HBs are less commonly seen in the spinal cord and rarely occur elsewhere in the CNS .
Cerebellar hemangioblastomas are traditionally classified into 4 types. Type one is a simple cyst without
macroscopic nodule. Type II ( most common ) is a cyst with a mural nodule. Type III are solid tumours and type IV are
solid tumours with small internal cysts.

Question 4

4. Which of the following statements are correct about Neurofibromatosis type 1 (NF-1):
   (a) Plexiform neurofibromas are pathognomonic for NF-1
   (b) Has an incidence of around 1 in 3000
   (c) 1-10 % of neurofibromas undergo malignant transformation.
   (d) Anterior vertebral scalloping is characteristic.
   (e) Pulmonary parenchymal abnormalities are seen in up to 20 % of cases.

Answer 4

Answers:
(a) Correct
(b) Correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
Neurofibromatosis shows posterior scalloping and enlargement of intervertebral foramen due to dural ectasia and
neurofibroma of nerve roots.
Other features are ribbon ribs, bowing of long bones, pseudoarthrosis and cystic osteolytic lesions.

Question 5

5. Which of the following statements are correct about MRI features of multiple sclerosis:
   (a) Corpus callosum lesions are best visualized on axial view.
   (b) T2W spin echo is superior to FLAIR for posterior fossa lesions.
   (c) Whiter matter lesions are more conspicuous than grey matter lesions.
   (d) Ring enhancement on post gadolinium T1W MRI suggests an alternative diagnosis.
   (e) 10-15 % of patients have lesions limited to the spinal cord.’

Answer 5

Answers:
(a) Not correct
(b) Correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
MS plaques are classically seen in periventricular and juxtacortical white matter. Involvement of corpus callosum is
characteristic and is best seen on Sagittal images.
Both solid and ring enhancement may occur. Incomplete ring enhancement is seen in larger MS plaques

Question 6

6. Which of the following statements are correct about Chiari malformation:
   (a) In normal physiology, cerebellar tonsils descend with increasing age.
   (b) Cerebellar tonsils laying 3 mm below the foramen magnum is a normal finding in the second decade.
   (c) Is usually associated with other congenital brain anomalies.
   (d) Is rarely associated with spinal cord lesions.
   (e) Is associated with Klippel-Feil anomaly (fused cervical vertebrae).

Answer 6

Answers:
(a) Not correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Correct
Explanation:
In normal physiology, cerebellar tonsils ascend with increasing age. In Chiari 1, there is downward displacement of
tonsils below the foramen magnum by more than 5 mm.
It is usually associated with spinal cord and skull base abnormalities rather than other brain anomalies

Question 7

7. Which of the following statements are correct about Tuberous sclerosis:
   (a) Cortical tubers enhance following intravenous contrast in the majority of cases on CT.
   (b) Subependymal nodule enhancement indicates malignant transformation.
   (c) Subependymal giant cell astrocytoma is seen in the 10-20 % of cases.
   (d) Renal angiomyolipomas are seen in 5-10% of cases.
   (e) Cardiac rhabdomyoma is a recognized manifestation

Answer 7

Answers:
(a) Not correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
In tuberous sclerosis, the cortical tubers are seen in 95% of patients although enhancement is seen in less than 5% of tubers.
30-80% of all subependymal nodules enhance after intravenous contrast but it does not indicate malignant
transformation.
Renal Angiomyolipomas are seen in 40-80% of cases of tuberous sclerosis.

Question 8

8. Which of the following statements are correct about Subarachnoid hemorrhage (SAH):
   (a) A normal CT within 24 h of onset of symptoms excludes SAH.
   (b) The most common etiology is trauma.
   (c) Focal interhemispheric blood suggests an anterior communicating artery aneurysm rupture.
   (d) Blood in the 4th ventricles is a typical feature of posterior communicating artery aneurysm rupture.
   (e) SAH detected on CT more than 1 week after the initial hemorrhage suggests recurrent bleeding.

Answer 8

Answers:
(a) Not correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
A ruptured intracranial aneurysm is the most common aetiology and accounts for 72% of cases of SAH.
A normal CT within 24 hours can exclude SAH in 90% of cases but not always.
4th ventricle blood is common with posterior inferior cerebellar artery aneurysms.

Question 9

9. Which of the following statements are correct about Congenital cholesteatoma of the middle ear:
   (a) 80 % of middle ear cholesteatoma are congenital in origin
   (b) Facial nerve palsy is a recognized complication.
   (c) The anterosuperior aspect of the middle ear is a typical location.
   (d) MRI is the imaging modality of choice.
   (e) Is associated with poorly pneumatised mastoid air cells:

Answer 9

Answers:
(a) Not correct
(b) Correct
(c) Correct
(d) Not correct
(e) Not correct
Explanation:
Congenital cholesteatoma accounts for 2% of all cholesteatomas and are clinically differentiated from acquired as
they occur behind an intact tympanic membrane in patients without a history of tympanic perforation or otorrhoea.
CT provides more accurate information regarding the mass and bony structures than MRI.
Well pneumatised mastoid air cells are seen in congenital cholesteatomas than in acquired

Question 10

10. Characteristic features of Herpes simplex encephalitis (HSE) in adults include:
    (a) Unilateral cerebral involvement
    (b) Infection by HSV type II
    (c) Untreated infection has a mortality rate of 50-70 %
    (d) Gyriform enhancement on contrast enhanced CT
    (e) High signal in the cingulated gyrus on T2W MRI

Answer 10

Answers:
(a) Not correct
(b) Not correct
(c) Correct
(d) Correct
(e) Correct
Explanation:
Neonatal herpes is caused by HSV II and herpes in adults is caused by HSV I.
In adults, herpes initiates as unilateral involvement of limbic system ( temporal bones, insular cortex, subfrontal area
and cingulated gyri) but eventually follows bilaterally.
CT performed early in the course of illness may be normal or only subtly normal.

Question 11

11. Concerning the submandibular space:
    (a) Anteriorly there is free communication between the submandibular space and the sublingual space.
    (b) The superficial lobe of the submandibular gland lies inferolateral to mylohyoid.
    (c) Intraglandular ducts are seen as linear hypoechoic structures on ultrasound.
    (d) Stenson’s duct exits in the floor of the mouth at the base of the frenulum.
    (e) As with the parotid gland, normal lymph nodes are found within the submandibular gland

Answer 11

Answers:
(a) Not correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Not correct
Explanation:
Submandibular and sublingual space communicates posteriorly.
Intraglandular ducts are seen as linear hyperechoic structures on USG.
Wharton’s duct exits in the floor of mouth at the base of frenulum.
Normal lymph nodes are not found in the submandibular gland.

Question 12

12. Which of the following statements are correct about Pyogenic brain abscesses:
    (a) Most commonly occur secondary to a generalised septicaemia.
    (b) Typically occur at the corticomedullary junction.
    (c) On CT have a smooth regular wall with relative thinning of the lateral wall.
    (d) Are more common in the occipital lobes than the frontal lobes.
    (e) The most common causative organism is Staphylococcus.

Answer 12

Answers:
(a) Not correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Not correct
Explanation:
32% of the pyogenic brain abscesses could be due to generalised septicaemia for example, from a lung abscess or
pneumonia. However 41% occur secondary to extension from paranasal sinus infection.
The occur most commonly in the frontal lobes than in the occipital lobes.
On CT there is a relative thinning of the medial wall due to would blood supply of white matter which leads to the
rupture of the abscess into the ventricular system.
Most common causative organism is streptococcus.

Question 13

13. Regarding subarachnoid haemorrhage:
    (a) It occurs secondary to arteriovenous malformation in 10% of cases.
    (b) It is associated with subdural haemorrhage in 20% of cases.
    (c) 15-20% of patients will have multiple aneurysms.
    (d) MRI is the best modality for detecting early subarachnoid haemorrhage.
    (e) Cerebral vasospasm is maximal from 48 to 72 hours after the event.

Answer 13

Answers:
(a) Correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Not correct
Explanation:
Subarachnoid haemorrhage is associated with subdural haemorrhage in 5% of the cases.
Initially subarachnoid haemorrhage may not be seen on MRI, hence CT is used for earlier detection of subarachnoid
haemorrhage.
Cerebral vasospasm occurs at 5-17 days after the event of subarachnoid haemorrhage.

Question 14

14. Concerning orbital mass lesions:
    (a) 50% of patients with optic nerve glioma have neurofibromatosis Type 1.
    (b) On MRI, retinoblastoma usually enhances following intravenous gadolinium.
    (c) Rhabdomyosarcoma of the orbit presents with rapid onset proptosis and visual loss.
    (d) Inflammatory orbital pseudotumour involves the muscle tendons.
    (e) 60-80% of children with retinoblastoma have bilateral tumours.

Answer 14

Answers:
(a) Not correct
(b) Correct
(c) Not correct
(d) Correct
(e) Not correct
Explanation:
25% of the patients with optic nerve glioma have neurofibromatosis type I however only 15% of the patients with
neurofibromatosis type I have optic nerve glioma.
In the rhabdomyosarcoma of the orbit, there is rapid onset of proptosis however vision is spared.
Only 20-40% of retinoblastomas occur bilaterally in children.

Question 15

15. Which of the following statements are correct about pineal region masses:
    (a) Pineoblastomas are categorised as part of the primitive neuroectodermal tumour group.
    (b) Pineoblastomas usually show poor enhancement.
    (c) Germinomas are 10 times more common in males than females.
    (d) Pineal germinomas are associated with Parinaud’s syndrome.
    (e) Germinomas are hypodense on unenhanced CT.

Answer 15

Answers:
(a) Correct
(b) Not correct
(c) Correct
(d) Correct
(e) Not correct
Explanation:
Pineoblastomas show avid enhancement on post contrast images.
The isodense to hyperdense on CT.
They are similar to medulloblastoma as the both are part of neuroectodermal tumour group.

Question 16

16. Regarding differentiation between epidermoids and dermoids of the brain:
    (a) Epidermoids more closely resemble cerebrospinal fluid on MRI.
    (b) Both are formed due to enclosure of ectodermal elements when the neural tube closes.
    (c) Epidermoids are more common.
    (d) Epidermoids may become malignant.
    (e) Fat-fluid level on imaging is highly suggestive of dermoids

Answer 16

Answers:
(a) Correct
(b) Correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
Dermoids and epidermoids are benign lesions and slow-growing and never become malignant.

Question 17

17. Concerning cerebellopontine angle masses:
    (a) Meningiomas are the second commonest cerebellopontine angle mass.
    (b) Meningiomas commonly cause expansion of the internal auditory canal.
    (c) Meningiomas are typically brighter on T2 weighted MRI than T1.
    (d) Epidermoids have the same signal as cerebrospinal fluid on MRI.
    (e) Acoustic neuromas usually enhance poorly on post-contrast scans.

Answer 17

Answers:
(a) Correct
(b) Not correct
(c) Not correct
(d) Correct
(e) Not correct
Explanation:
Meningiomas do not cause expansion of internal auditory canal.
They are usually less bright on T2-weighted MRI.
Acoustic neuromas usually enhance avidly on postcontrast images.

Question 18

18. Concerning the differences between cortical contusions and diffuse axonal injury (DAI):
    (a) Patients with cortical contusions are much less likely to have had loss of consciousness.
    (b) Patients with cortical contusions usually have a better prognosis.
    (c) Cortical contusions are more commonly haemorrhagic than DAI.
    (d) CT is the best modality to diagnose acute DAI.
    (e) Most patients with DAI suffer immediate loss of consciousness

Answer 18

Answers:
(a) Correct
(b) Correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
Diffuse axonal injury are seen much better on MRI than CT.
On MRI diffusion weighted images and susceptibility weighted images are most

Question 19

19. Concerning differences between primary CNS lymphoma and toxoplasmosis:
    (a) Subependymal extension across the corpus callosum is more likely to occur in toxoplasmosis.
    (b) High signal on T2 weighted MRI favours lymphoma.
    (c) Toxoplasmosis is more frequently multiple.
    (d) Ring enhancement following contrast administration favours lymphoma.
    (e) The lesions are usually smaller in lymphoma.

Answer 19

Answers:

(a) Not correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Not correct
Explanation:
CNS lymphoma shows subependymal extension across the corpus callosum. CNS lymphoma and toxoplasmosis
lesions can be smaller as well as large and should not be differentiated on basis of size.
Toxoplasmosis shows high signal on T2-weighted MRI and shows ring enhancement on post contrast images.

Question 20

20. Which of the following statements are correct about cerebellar medulloblastoma:
    (a) Is more common in females.
    (b) Is the commonest paediatric brain tumour.
    (c) 75% of patents are less than 15 years of age.
    (d) Calcification occurs in 40-50%.
    (e) Is associated with basal cell carcinomas

Answer 20

Answers:
(a) Not correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
Medulloblastoma is the second commonest paediatric tumour, second only to astrocytoma however it is the
commonest paediatric posterior fossa tumour.
It occurs more commonly in males.
Calcifications are seen in up to 20% of patients. Cystic changes or necrosis are seen in up to 50%. They are usually
hyperdense on CT. On MRI, they are usually hypointense to grey matter on T1 weighted images and variable
appearance on T2-weighted images. Oedema is almost always seen.

Question 21

21. Concerning the differentiation between optic nerve glioma and optic nerve sheath meningioma:
    (a) A widened optic canal is seen more commonly in optic nerve glioma.
    (b) Optic nerve sheath meningioma affects an older age group.
    (c) Optic nerve glioma typically shows the ‘tram-track’ sign on enhancement.
    (d) Calcification is more commonly seen with optic nerve glioma.
    (e) Optic nerve glioma may cause orbital hyperostosis.

Answer 21

Answers:
(a) Correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Not correct
Explanation:
Optic nerve sheath meningioma affects older age usually middle aged woman.
Calcification can be seen with optic nerve meningioma but is the rarely seen with optic nerve glioma.
Optic nerve sheath meningioma typically shows the tram track sign on enhancement.
Optic nerve sheath meningioma causes orbital hyperostosis.

Question 22

22. Concerning intracranial lymphoma:
    (a) It is usually a Hodgkin’s lymphoma.
    (b) Secondary lymphoma more commonly involves the leptomeninges than the brain parenchyma.
    (c) It is usually hypodense on unenhanced CT.
    (d) It is normally high signal on T2 weighted images.
    (e) Toxoplasmosis may mimic lymphoma in the brain

Answer 22

Answers:
(a) Not correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Correct
Explanation:
CNS lymphoma are usually B-cell non-Hodgkin’s lymphoma. They are usually hyperdense on unenhanced CT.
There show intermediate to low signal on T2-weighted MR images.

Question 23

23. Concerning posterior fossa tumours in children:
    (a) 80% of medulloblastomas arise from the vermis.
    (b) Juvenile pilocytic astrocytomas are the second commonest posterior fossa tumour.
    (c) Juvenile pilocytic astrocytomas usually calcify.
    (d) Brainstem gliomas mostly affect the midbrain.
    (e) Ependymoma seeds to the CSF in 30% of cases

Answer 23

Answers:
(a) Correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Correct
Explanation:
Juvenile pilocytic astrocytomas are at the second commonest posterior fossa tumours after medulloblastoma. Only
20% of these calcify.
Brainstem gliomas mostly affect the pons.

Question 24

24. Concerning intraorbital pathology:
    (a) The lacrimal gland is the most frequently involved orbital structure in idiopathic inflammatory pseudotumour.
    (b) Idiopathic inflammatory pseudotumour is unilateral in 40-50% of cases in adults.
    (c) Optic nerve glioma is the commonest tumour arising from the optic nerve sheath complex.
    (d) Use of steroids differentiates idiopathic inflammatory pseudotumour from lymphoma.
    (e) Thyroid eye disease is the most common disorder affecting the orbit.

Answer 24

Answers:
(a) Correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
Pseudotumour is unilateral in 80% of the cases in adults.
Use steroids in differentiating pseudotumour from lymphoma is not useful.

Question 25

25. Which of the following statements are correct about Juvenile angiofibromas: (a) Biopsy is contraindicated. (b) Almost exclusively affects females. (c) Widening of the pterygopalatine fossa is only seen in advanced cases. (d) Is the commonest benign nasopharyngeal tumour. (e) Invasion of the sphenoid sinus occurs in up to two thirds of cases.

Answer 25

Answers: (a) Correct (b) Not correct (c) Not correct (d) Correct (e) Correct Explanation: Juvenile angiofibromas affects only males. Widening of pterygopalatine fossa is seen in 90% of the cases. Due to significant vascularity and the risk of haemorrhage, biopsy is always contraindicated

Question 26

26. Regarding sonography of abnormal neck lymph nodes: (a) Malignant nodes have sharp borders, shereas benign nodes usually have unsharp borders. (b) Regardless of the primary tumour, the presence of a metastatic node reduces the 5-year survival rate by 50%. (c) Metastatic nodes are usually hyperechoic when compared to the adjacent muscles. (d) Nodal calcification is common in metastatic nodes from follicular carcinoma of the thyroid. (e) The presence of peripheral vascularity is highly suggestive of malignancy.

Answer 26

Answers: (a) Correct (b) Correct (c) Not correct (d) Not correct (e) Correct Explanation: Metastatic nodes are usually hyperechoic compared to the adjacent muscles. However metastatic nodes from papillary carcinoma of thyroid tend to be hyperechoic. Nodal calcification is seen in metastatic nodes from papillary and medullary carcinoma thyroid.

Question 27

27. Concerning sellar masses: (a) Craniopharyngioma usually contains bright areas on T1 weighted images. (b) Craniopharyngioma is more commonly calcified in adults than children. (c) Craniopharyngioma is the commonest childhood sellar mass. (d) Craniopharyngioma normally has a regular outline on imaging. (e) Rathke’s cleft cyst develops from squamous epithelium in the sphenoid sinus.

Answer 27

Answers: (a) Correct (b) Not correct (c) Correct (d) Not correct (e) Not correct Explanation: Craniopharyngiomas are 80% calcified in children and 40% calcified in adults. They usually have lobulated and irregular margins. Rathke’s cleft cyst develops from the anterior lobe of the pituitary gland

Question 28

28. Regarding Tornwaldt’s cysts, which of the following are correct? (a) They do not enhance after contrast on computed tomography (CT). (b) They are midline in location. (c) They are usually low signal on T1 weighted MRI sequence. (d) The erode bone. (e) They typically arise caudal to Rathke’s pouch cyst.

Answer 28

Answers: (a) Correct (b) Correct (c) Not correct (d) Not correct (e) Correct Explanation: Tornwaldt cyst usually show high signal on T1-weighted MR images due to high protein content in the cyst. They do not cause bony erosion. They are rarely calcified and usually appear hypodense on CT.

Question 29

29. Which of the following are correct regarding dermoid and epidermoid cysts? (a) Epidermoid cysts are usually unilocular. (b) High signal on T1 weighted MRI is diagnostic of a dermoid cyst. (c) Dermoid cysts may be distinguished from lipoma on T1 weighted MRI. (d) The most common location of dermoid cyst in the head and neck is the orbit. (e) Epidermoid cysts have high signal on T2 weighted MRI scans

Answer 29

Answers: (a) Correct (b) Not correct (c) Not correct (d) Correct (e) Correct Explanation: Dermoid cysts are usually hyperintense on T1-weighted MR images but this signal characteristic can be seen in other lesions example lipoma. Hence their differentiation is not recommended on T1-weighted MR images. Dermoid cysts are usually seen in orbit, oral and nasal cavities however orbit is the most common site.

Question 30

30. Concerning imaging of the larynx, which of the following are correct? (a) Cricoid cartilage typically fractures in at least two places following trauma. (b) More than 90% of laryngeal cancers are squamous cell tumours. (c) The arytenoids usually dislocate rather than fracture during trauma. (d) Glottic cancers typically arise from the anterior half of the vocal cord. (e) AT presentation, subglottic tumours are frequently non-operative

Answer 30

Answers: (a) Correct (b) Correct (c) Correct (d) Correct (e) Correct Explanation: Following trauma, the arytenoids dislocate anteriorly and superiorly . Squamous carcinoma of larynx occurs most commonly at glottic location. Subglottic tumours are rare and involves trachea, oesophagus and thyroid and hence have a poor prognosis

Question 31

31. Regarding thyroid carcinoma, which of the following are correct? (a) Lymph node spread occurs in 90% of patients with papillary cell carcinoma. (b) Follicular carcinoma accounts for 60% of all thyroid carcinomas. (c) Early haematogenous spread occurs in follicular carcinoma. (d) Anaplastic carcinoma demonstrates no radioiodine uptake. (e) Multiple endocrine neoplasia (MEN) type IIb may be associated with medullary cell carcinoma

Answer 31

Answers: (a) Not correct (b) Not correct (c) Correct (d) Correct (e) Correct Explanation: Papillary carcinoma of thyroid accounts for 60%, follicular 20%, anaplastic 10% and medullary 5% . Metastasis to nodes from papillary carcinoma occurs in 40% of adult cases and 90% of child cases.

Question 32

32. Which of the following are correct about fibrous dysplasia? (a) Facial bones are rarely involved. (b) Exophthalmos is a recognised feature. (c) There is an association with Cushing’s syndrome. (d) In the calvaria, the frontal bone is most commonly involved. (e) It effects the maxilla more frequently than the mandible.

Answer 32

Answers: (a) Not correct (b) Correct (c) Correct (d) Correct (e) Correct Explanation: Fibrous dysplasia typically presents before the age of 30 years. The most common sites of involvement of the ribs, cranial, facial bones and femur and tibia.

Question 33

33. Which of the following are correct regarding lesions of the jaw? (a) Simple bone cysts are more common in the maxilla than the mandible (b) A dentigerous cyst develops around an unerupted tooth. (c) Dentigerous cysts are associated with basal cell naevi. (d) Radicular cysts arise in relation to the tooth apex. (e) Ameloblastoma occurs more frequently in the maxilla.

Answer 33

Answers: (a) Not correct (b) Correct (c) Correct (d) Correct (e) Not correct Explanation: Bone cysts are unilocular and well-defined. They may be trauma-related and typically arise in the body of mandible. About 75% of neuroblastomas arise in the mandible, usually at the angle. The may be multilocular and are cystic expansile lesions, which often recur after excision.

Question 34

34. Which of the following are correct regarding trauma of the neck? (a) The most common site of vertebral artery injury in blunt trauma to the neck is at the C5/C6 level. (b) Multiple levels are involved in 20% of fractures of the cervical spine. (c) In blunt neck trauma, dissection of the extracranial carotid artery is asymptomatic in 10% of cases. (d) Fracture of the odontoid peg most commonly involves the tip. (e) Barium swallow has poor sensitivity for pharyngoesophageal injury is blunt neck trauma.

Answer 34

Answers: (a) Not correct (b) Correct (c) Not correct (d) Not correct (e) Not correct Explanation: Vertebral artery injury is usually due to stretching and occurs most frequently at the C1-C2 level. Vertebral artery injuries are more common than carotid artery injuries in blunt neck trauma. Dissection of the extracranial carotid artery is asymptomatic at presentation in 50% of the cases. Diagnosis may be delayed.

Question 35

35. Which of the following are correct regarding Klippel-Feil syndrome? (a) Vertebral fusion involves the bodies and neural arches. (b) Coarctation is a feature. (c) It is associated with Sprengel’s shoulder deformity. (d) Conductive hearing loss is a feature. (e) Lymphoedema is a feature

Answer 35

Answers: (a) Correct (b) Correct (c) Correct (d) Correct (e) Correct Explanation: Klippel Feil syndrome is also associated with syringomyelia, platybasia, clubfoot, hemivertebrae and congenitally heart diseases. Vertebral fusion may involve the craniovertebral junction and cervicothoracic junctions.

Question 36

36. Which of the following are correct regarding fractures of the cervical spine? (a) Flexion teardrop fractures involve the superior endplate of the vertebral body. (b) Hangman’s fracture is a bilateral fracture of the neural arches of C2. (c) Unilateral interfacet joint dislocation is a stable injury. (d) Clay shoveler’s fracture is stable. (e) In bilateral interfacetal dislocation, there is anterior translocation of the involved vertebra by at least 50% of the diameter of the subjacent vertebrae.

Answer 36

Answers: (a) Not correct (b) Correct (c) Correct (d) Correct (e) Correct Explanation: Flexion teardrop fractures involve avulsion of the anterior inferior corner, usually of the C2 vertebral body with displacement of the involved vertebral body into the spinal column. There is destruction of all soft tissue structures with an associated acute anterior cervical cord syndrome.

Question 37

37. Which of the following are correct regarding salivary gland calculi? (a) Most submandibular stones are radio-opaque. (b) Submandibular stones typically occur within Wharton’s duct. (c) Asymptomatic Intraductal parotid stones can be an incidental finding on CT. (d) More than 80% of salivary gland stones occur in the submandibular gland. (e) About 25% of patients have multiple stones.

Answer 37

Answers: (a) Correct (b) Correct (c) Correct (d) Correct (e) Correct Explanation: About 10% to 20% of salivary gland calculi occur in parotid gland. About 80% of submandibular stones and 60% of parotid stones are radiopaque.