In order to see how the surgeon’s (i.e. my) experience affected outcome following meningioma surgery over time, 800 meningiomas were subdivided into groups of 200 each.  The following time frame was required to accumulate the experience of 200 cases each:

Group I:  7 years

Group II:  3 years and 3 months

Group III: 2 years and 6 months

Group IV: 2 years and 6 months

There was a gradual increase in the incidence of “Normal” outcome group in each of the successive groups of 200 cases, going from 83.5 % in Group I, eventually to 91 % in Group IV.  However, this difference (i.e. improvement) was not statistically significant until the last group (Group IV) of 200 cases.  In other words, it takes a surgeon at least 600 cases of accumulated experience to make a statistically significant improvement in outcome in meningioma surgery.  In short, surgeon’s experience is a critically important factor in determining outcome in meningioma surgery.               

Previous radiation:  In order to study whether a history of radiation influences outcome in meningioma surgery, “Radiation (Yes)” group was compared to those with no prior radiation with respect to outcome (GOS) (based on a review of 800 operative cases, personal series).  A total of 93 patients had previous radiation.  Many of these patients also had prior operations.  

The incidence of “Good” outcome (GOS 4 & 5) patients goes down significantly from the “No radiation” group to the “Prior (Yes) radiation” group.

Prior radiation, similar to previous surgery, causes scar tissue formation around the tumor, making exposure and identification of the tumor and the surrounding “normal” anatomic structures difficult and, at times, dangerous, adding to overall surgical risks.  Patients with a history of previous radiation do less well following surgery.

Previous surgery:  To see whether or not a history of prior surgery had any influence on outcome following meningioma surgery, “Previous surgery (Yes)” group was compared to those with no prior surgery with respect to outcome (GOS) (based on a review of 800 operative cases, personal series).  A total of 93 patients had previous operation(s).

The incidence of “Good” outcome (GOS 4 & 5) patients goes down significantly from the “No surgery” group to the “Prior (Yes) surgery” group.

In brain surgery, prior operation causes scar tissue formation at the site of surgery, making exposure and identification of the tumor and the surrounding “normal” anatomic structures difficult and, at times, dangerous, adding to overall surgical risks.  Patients with a history of previous surgery do less well following surgery.

Symptoms:  Symptomatic tumors were compared against those causing no symptoms (“Asymptomatic”) with respect to outcome following surgery (based on a review of 800 operative cases, personal series):

Asymptomatic:  Tumors causing no symptoms (i.e. “incidental” tumors)

Symptomatic:  Tumors producing significant symptoms or neurological deficits

The incidence of “Good” outcome (GOS 4 & 5) patients goes down significantly from the “Asymptomatic” tumor group to the “Symptomatic” group.  In particular, the incidence of “normal” outcome is about 98% in the “Asymptomatic” group as compared to 81% in the “Symptomatic” group.  In short, whether or not the tumor is causing any preoperative symptoms does influence how well patients do following their surgery.  This may have to do the the larger size and the presence of peritumoral edema (swelling) in the “Symptomatic” group of patients.  In short, patients with “asymptomatic” meningiomas do extremely well following surgery.

Size of the tumor was assessed with respect to outcome (GOS) by dividing into 3 groups (based on a review of 800 operative cases, personal series):

Small:  Less than or equal to 2 cm in largest diameter

Medium:  Between 2.1 and 4 cm in largest diameter

Large:  Larger than 4 cm in largest diameter   

The incidence of “Good” outcome (GOS 4 & 5) patients goes down significantly, again in a step-wise manner, from the “Small” tumor group to the “Medium” group, then from the “Medium” group to the “Large” group.   No “Poor” outcome was seen in the “Small” group.  In short, the tumor size also does matter in how well patients do following meningioma surgery.  Patients with “small” meningiomas do extremely well following surgery.
    

Age was assessed with respect to outcome (GOS) by dividing into 3 groups (based on a review of 800 operative cases, personal series):

Group I:  Age less than 60

Group II:  Age between 61 and 70

Group III:  Age greater than 70 

The incidence of “normal” patients (GOS 5) goes down significantly from the Group I to II, then from II to III.   Young patient (<60) do very well from meningioma surgery, while older patients fared less optimally.  In short, age also does matter in how well patients fare following meningioma surgery.

Location was analyzed with respect to outcome (GOS) by dividing the patients into 3 groups according to the level of technical difficulty posed by the tumor location (based on a review of 800 operative cases, personal series):

Simple:  Convexity, lateral sphenoid wing, cerebellar convexity, posterior petrous, posterolateral foramen magnum

Moderate:  Falx, parasagittal, middle sphenoid wing, olfactory groove, lateral tentorial,  Transverse/sigmoid sinus

Complex:  Anterior clinoid, tuberculum sella, cavernous sinus, petroclival, ventral petrous, medial tentorial, dorsal clinoid, pineal, ventral foramen magnum

No death was encountered in the “Simple” location group, and the overall incidence of excellent outcome (GOS 4 & 5) can be seen to be decreasing in a step-wise fashion going from the “Simple” to “Moderate” locations, then going from the “Moderate” locations to the “Complex” locations.

In summary, patients with meningiomas in “simple” locations do very well following surgery compared to those with tumors in more difficult or “complex” locations.  Location does matter in determining the outcome following meningioma surgery.

Co-morbidity (i.e. presence of any medical illnesses coexisting with meningioma at the time of surgery) was analyzed respect to outcome (GOS) using the commonly used ASA (American Society of Anesthesiologists) Physical Status Classification (ASA I – Healthy, ASA II – Mild systemic disease, ASA III – Severe systemic disease, ASA IV – Severe systemic disease that is constant threat to life, ASA IV – Moribund).   Patients with ASA Classification IV or V are not candidates for meningioma surgery as they are too ill to undergo a major operation.  (Based on a review of 800 operative cases, personal series)

Healthy patients did much better than those with significant medical illness(es).  For example, no patient in the ASA Groups I or II died after meningioma surgery.  Death was encountered only in the ASA III patients.  Additionally, the incidence of excellent outcome (GOS 4 & 5, close to 100% in the ASA Group I) decreased in a step-wise fashion in going from the ASA 1 to the ASA 2 group, and subsequently from the ASA 2 to the ASA 3 groups.

In summary, healthy patients do very well following meningioma surgery.

Based on a review of 800 personal cases of meningioma surgery as mentioned in the last section, this time we did another study in order to determine the factors that influence outcome in meningioma surgery.  In summary these important factors include the following:

Internal factor (inherent to patients/tumors):

Co-morbidity (patient’s health status)

Location

Age

Size

Symptoms

Prior surgery

Prior radiation

External factor:

Surgeon’s experience (i.e. the “learning curve” effect)

Using the first letters of the first five factors (Co-morbidity, Location, Age, Size, Symptoms), I have come up with an acronym – “CLASS”- for teaching residents and young neurosurgeons the important factors that determine outcome in meningioma surgery.  Also, utilizing these outcome factors, I have developed the “CLASS” algorithmic scale for patient selection in meningioma surgery.

Additional reading:

Factors Influencing Outcome in Meningioma Surgery

The Novel CLASS Algorithmic Scale for Patient Selection

Sade B, Lee JH:  Factors Influencing Outcome in Meningioma Surgery.  In:  “Meningiomas” (JH Lee, ed.), pp. 213-216, Springer, London, 2008

Lee JH, Sade B:  The Novel “CLASS” Algorithmic Scale for Patient Selection in Meningioma Surgery.  In:  “Meningiomas” (JH Lee, ed.), pp. 217-221, Springer, London, 2008

I have reviewed my personal operative series of 800 consecutive cases performed at the Cleveland Clinic where I had a 21-year tenure as Professor & Director, Skull Base Surgery Center, and this study represent the largest of its kind to date.  (Prior study based on 600 cases was published in my book, Meningiomas (JH Lee, ed.), see reference below.)

How patients were doing 6 weeks after their surgery was analyzed using Glasgow Outcome Scale, a common outcome measure used by neurosurgeons:

GOS I – Dead

GOS II – Vegetative

GOS III – Dependent

GOS IV – Independent

GOS V – “Normal” life, returned to preoperative employment

GOS I-III are considered as “poor” outcome, while GOS IV-V represent “good” outcome.

At 6 weeks, the following is the outcome of my 800 meningioma patients:

GOS I:    5 (0.6%)

GOS II:   6 (0.8%)

GOS III:  23 (2.9%)

Total “Poor” outcome (GOS I-III): 34 (4.3%)

GOS IV:  70 (8.8%)

GOS V:  696 (87%)

Total “Good” outcome (GOS IV-V): 766 (95.7%)

Additional reading:

Operative Outcome Following Meningioma Surgery: A Personal Experience of 600 Cases

Lee JH, Sade B:  Operative Outcome Following Meningioma Surgery:  A Personal Experience of 600 Cases.  In: “Meningiomas” (JH Lee, ed.), pp. 209-212, Springer, London, 2008