Surgery Of Olfactory Groove Meningiomas Biology Essay

Olfactory channel meningiomas history for 8 to 13 % of all intracranial meningiomas. ( 1,3,5,13,14 ) It arise in the midplane over the cribriform home base and frontosphenoid sutura and busy the floor of the anterior cranial pit widening all the manner from the the cresta galli to the tuberculum sellae. ( 6.14 ) As the tumour extends posteriorly it pushes the ocular nervus and decussation downwards and posteriorly, this will distinguish OGM from tuberculum sellae meningiomas which displace the ocular nervousnesss superolaterally and therefore occupies a subchiasmal place. ( 15,24,29 ) Different surgical attacks are described for resection of OGMs including the traditional frontlet or bifrontal attack, ( 4,9 ) the pterional attack, ( 5,13,31 ) the more aggressive attacks for tumours widening in the paranasal fistulas and orbits including the transbasal attack, ( 23 ) the subcranial attack, ( 3,10 ) the frontoorbital attack, ( 8 ) frontlet or bifrontal craniotomy combined with orbital or rhinal osteotomies ( 29,30 ) and craniofacial resection. ( 26,27 ) Contrary to the aggressive surgical approaches the endoscopic glabellar attack is besides described. ( 16 ) Perneczky and his collegues ( 25 ) advocated the minimally invasive supraocular minicraniotomy for a assortment of skull base tumours. Surgical resection of little to moderate-sized OGMs is non hard. Large tumours affecting the anterior intellectual complex present surgical challenge and demands extended microsurgical dissection. ( 29 )

Method

Between 2000 and 2009, twenty three patints with olfactive channel meningiomas were operated. Among the patients were 15 females and 8 males. The age ranged from 26 old ages to 65 old ages with a mean of 45.2 old ages ( table I ) . Showing symptoms and marks are described in tabular array ( II ) . Headache, papillodema, anosmia were the most common presenting manifestations, followed by mental manifestations and decline of vision. Five patients have epilepsy as the first presenting symptom.

Radiological findings

Computed imaging ( CT ) and magnetic resonance imagination ( MRI ) were done for all patients. Tumor diameter varied from 3.3 to 6.1 centimeter ( average 4.7 centimeter ) . Three patients had undergone old operation elsewhere and presented to us as recurrent tumours. Hyperostosis was present in 4 patients, calcification in 9 patients and incasement of the anterior intellectual arteria composite in 5 patients. Tumor extension to the paranasal sinuses was observed in 6 patients.

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Surgical technique

The patient is placed in the supine place. In big tumours more than 4 centimeter we request from the anesthesiologist to infix a timber drain which is opened after craniotomy to run out CSF to minimise abjuration. The skin scratch is made merely behind the hair line from zygoma to zygoma. The scalp is reflected anteriorly. A pericranial flap is elevated and care taken to maintain it integral for subsequently fix of the anterior skull base. A craniotomy is performed widening anteriorly every bit near as possible to the orbital roof. The radical line of the craniotomy normally involves the frontal air fistulas, the mucous secretion membrane is wholly removed and sinus cranialized. The dura is opened parallel to the base and the superior sagittal fistula is ligated and cut at the caecal hiatuss and the falx is cut to open up the surgical field. The tumour capsule was foremost opened and tumour debulked with the aid of CUSA. Tumor resection is done in bit-by-bit manner. Effort is made to devascularise the tumour at the skull base to ease resection with minimum blood loss. The dural beginning of the tumour is so resected and if hyperostosis is present it is removed by diamond drill. If there is paranasal sinus engagement, the fistula is entered and tumour resected from above. The skull base is so reconstructed utilizing pericranial flaps and or temporalis facia in the frontlet and ethmoidal air fistulas if they were opened.

Extent of tumour resection

The extent of tumour resection was classified harmonizing to the Simpson categorization. ( 28 ) Grade 1 indicates entire tumour resection with deletion of the infiltrated dura ; grade2 indicate entire tumour resection and curdling of the dural fond regard ; grade 3 indicates gross entire remotion without deletion of dural fond regards or epidural extension ; grade4 indicate subtotal tumour resection. In 20 patients tumours were wholly removed ( Simpson grade 1 and 2 ) and in three patients tumours were subtotally removed ( Simpson grade 3 and 4 ) . The cause for uncomplete tumour resection was inability to divide the tumour from the anterior intellectual arteria and these patients were referred to radiosurgery physician for farther direction.

Surgical result

Immediate postoperative CT scan was done in all patients. The most common determination was subdural hygroma in 9 patients particularly in big tumours and it disappeared spontaneously in the follow up period. Tumor bed haematoma occurred in three patients and needed surgical emptying in merely one patient who was awaken from anaethesia in a stuperosed status and he improved after emptying. Postoperative generalized ictuss occurred in 5 patients and were controlled with appropriate antiepileptic medicine. CSF rhinorrhea occurred in three patients and was successfully controlled by repeated lumbar drain and antibiotic coverage. Wound infection occurred in 3 patients and responded good to proper antibiotic intervention. Smell was lost in all but 3 patients in whom tumour resection was uncomplete ( table III ) .

Histopathological diagnosing

The pathology in all patients was Grade I meningiomas ( World Health Organization rating ) . The most common subtype was meningothelial meningioma ( 14 instances ) , followed by psamomatous meningioma ( 6 instances ) , and hempen meningioma ( 3 instances ) .

Tumor return

Tumor return occurred in one patient, she was a immature female operated 2003 with Simpson grade 2 deletion. During the modus operandi follow up in 2008 tumour return was seen and reoperation was done with entire deletion of the tumour which was of the meningothelial type.

Table I: Summary of 23 patients

Patient

Age

Gender

Maximal diameter

Extent of resection

1

44

F

5.2

Entire

2

26

F

5.7

Entire

3

42

F

4.8

Entire

4

53

F

6.1

Entire

5

65

Meter

3.9

Entire

6

51

Meter

5.1

Entire

7

39

F

6.1

Subtotal

8

62

F

3.7

Entire

9

40

F

4.4

Subtotal

10

56

Meter

4.8

Entire

11

47

F

4.2

Entire

12

38

Meter

5.5

Entire

13

34

F

4.8

Subtotal

14

35

Meter

3.3

Entire

15

34

F

4.1

Entire

16

43

F

3.6

Entire

17

42

F

3.9

Entire

18

54

Meter

5.2

Entire

19

43

Meter

5.5

Entire

20

49

F

5.2

Entire

21

46

Meter

3.7

Entire

22

52

F

5.1

Entire

23

46

F

5.4

Entire

Table II: Symptoms and marks No. of patients

Concern

21

Papillodema

11

Olfactory damage

11

Ocular damage

10

Mental alterations

10

Epilepsy

5

Ocular wasting

4

Foster Kennedy

2

Table Three: Operative complications

Complication

No. of patients

CSF rhinorrhea

3

Tumor bed haematoma

3

Anosmia

20

Wound infection

3

Partial ocular nervus hurt

1

Seizures

5

Fig 1: Upper berth and lower left: axial CT scan of a instance of olfactory channel meningioma ( notice the calcification ) : sagittal and coronal MRI of the same instance, lower right: postoperative CT scan after entire remotion.

Fig 2: Left and in-between: axial and coronal MRI of a instance of olfactory channel meningioma, right: postoperative CT scan after entire remotion.

Fig 3: Upper left: axial CT scan of a instance of olfactory channel meningioma ( notice the calcification ) , upper right: sagittal MRI of the same instance ( notice the paranasal sinus invasion ) , lower: postoperative CT scan after entire remotion.

Fig 4: Upper berth: axial CT scan of a instance of olfactory channel meningioma ( notice the calcification ) , in-between: axial and coronal MRI of the same instance ( notice the paranasal sinus invasion ) , lower: postoperative CT scan after entire remotion.

Discussion

Surgical attacks

Several surgical attacks have been used for resection of the OGMs runing from extended skull base approaches to minimally invasive endoscopic attacks. ( 3,5,9,13,16,25 )

The bifrontal attack proposed by Tonnis in 1938, ( 30 ) is recommended by others for remotion of big OGMs. ( 5,9,19 ) It is proposed that this attack allows the least sum of abjuration and gives direct entree to about both sides of the tumour. ( 5,19 ) The bifrontal attack allows besides early tumour devascularisation and gives good exposure for skull base Reconstruction. ( 5,10 ) The disadvantages include division of the superior sagittal fistula which contributes to post operative frontal lobe hydrops and encephalon puffiness, the old construct that the anterior tierce of the fistula can be safely ligated is no longer true. ( 13 ) The 2nd disadvantage is that the of import vascular construction and ocular setup are non visualized except after deletion of a large majority of the tumour. ( 13,29 ) In our survey we were able to counter these disadvantages by really anterior ligation of the fistula at the hiatuss caecum and carefull microsurgical dissection of the posterior portion of the tumour after good survey of the MRI T2weighted to see the relation of the anterior intellectual arteria composite to the tumour.

The pterional attack has the advantage of early designation and procuring the neurovascular constructions, besides the basal cisterns can be opened before working in the tumour doing the encephalon more slack. ( 13,19 ) The major disadvantages of this attack include a narrow working angle and long distance to the opposite side of the tumour. Besides the upper portion of the tumour is a unsighted country and important encephalon abjuration is needed to visualise it. In our survey we do non utilize the pterional attack due to the antecedently mentioned disadvantages and we tried to be every bit basal as possible to devascularise the tumour early in the process and debulk the tumour so with abjuration on the tumour capsule we are able to open the carotid cistern and visualise the neurovascular constructions bilaterally. In large tumours more than 4 centimeter we routinely used lumbar drain to evacuate CSF after lift of the bone flap. We use head rotary motion 15 grades to the contralateral side to see the epsilateral carotid and ocular and do the same thing on the opposite side profiting from the bilateral exposure in the bifrontal attack.

Extensive skull base approaches with bilateral or one-sided orbital osteotomy are proposed to give shorter distance to the tumour and minimise encephalon abjuration. ( 3,8 ) These attacks are clip devouring during gap and Reconstruction and are associated with increased hazard of CSF escape and we can avoid abjuration by being flush with the orbital roof and we can besides bore the interior facet of the superior orbital rim and any bump of the orbital roof for better exposure.

The per centum of entire tumour resection in other series ranged from 50 to 100 % . ( 3,5,6,30 ) The per centum of entire remotion is bettering with the coming of modern microsurgical techniques making up to 100 % in most of the recent series. ( 22,27 ) Subtotal remotion is normally associated with bony infiltration and paranssal fistulas invasion. ( 22,27 ) In our survey we used the high velocity drill to take the hyperostotic or infiltrated bone and we opened the infiltrated paranasal fistula from above to take the tumour with good Reconstruction which is best allowed with the bifrontal attack used in this survey.

Post operative morbidity and mortality are bettering in recent series due to the usage of microsurgical techniques. The chief causes of morbidity include CSF leake, meningitis, postoperative haematoma, subdural hygroma, declining of vision, motor shortage and ictuss. ( 3,5,22,27 ) In this survey there was no mortality and we have 3 instances of CSF rhinorrhea, one instance of one-sided deterioration of vision, 3 instances of wound infection and 5 instances of ictuss.

The return rate for OGMs ranges from 0 to 41 % in the literatures in macro and microsurgical processs with a follow up period of 3.7 to 25 old ages. ( 22,27 ) Surgical series of short continuance follow up show no return. Series with longer periods of follow up ( 10-20years ) show higher rates of return. ( 22,27 ) In this survey we have merely one return after entire remotion and this may be attributed to the comparatively short follow up period ( 6 months to 8 old ages with a mean of 2.6 old ages ) .

Decision

Bifrontal attack is a simple, safe, and broad attack for OGMs. Lumber CSF drainage after lift of the bone flap over- comes the non visual image of the basal cisterns early in the attack. It allows bilateral exposure for the tumour and the neurovascular constructions. Reconstruction of the cranial base is ideal through this attack which minimizes the hazard of CSF leak.

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