3° Clinical case: Meningioma

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3° Clinical case: Meningioma

 

Article by  Gianni Frisardi · Flavio Frisardi

 

Abstract:This clinical case, referred to as Balancer, involves a 60-year-old male patient experiencing postural and gait disturbances following prosthetic rehabilitation. The case will be analyzed using the same diagnostic framework applied in previous cases like Mary Poppins and Bruxer. The analysis focuses on correlations between temporomandibular disorders (TMD), posture, and occlusal balance, with particular emphasis on Centric Relationship and its influence on both occlusal stability and posture.

Recent studies, including those by Minervini et al., suggest a relationship between TMD and postural problems, positing that TMD affects neuromuscular balance, influencing body posture. Despite this, many clinicians remain skeptical about these connections. The case of Balancer raises concerns about the correlation between Centric Relationship and postural stability, presenting a situation where traditional manual centric positioning (used in orthognathic surgery) conflicted with Neuro Evoked Centric Relationship obtained via trigeminal root stimulation, revealing spatial misalignment.

Further exploration of neuromuscular balance and symmetry through electromyographic procedures highlighted significant discrepancies between the asymmetry detected in the EMG patterns and the neurological findings. The case underscores the importance of integrating both dental and neurological contexts to reach an accurate diagnosis, particularly when interpreting terms like "asymmetry." This case demonstrates that a seemingly trivial postural asymmetry could signify more severe neurological damage.

The clinical findings suggest that while there may be minor EMG asymmetry due to prosthetic imbalance, the neurological symptoms, including an absent jaw jerk and latency asymmetry in the Silent Period, indicate a deeper neurological issue rather than a simple dental malocclusion. The diagnostic model applied here aims to decrypt the central nervous system's machine language code to distinguish between functional postural disturbances and structural neurological damage.

Introduction

As now implicit, this clinical case too, which from now on we will call with a fancy name Balancer' due to its related symptoms of postural and gait disturbance after being prosthetically rehabilitated, will follow the presentation model of the previous clinical cases. The introduction will present topics relating to the diagnostic model in question on which we will make the first conceptual reflections highlighted by our dear and thoughtful Linus. A recent article by Minervini et al. asserts the following: TMD has ligament and muscle connections with the cervical area, therefore these connections have led to the hypothesis that posture problems may influence the development of TMD, therefore masticatory cycles should be balanced as unilateral chewing could alter the postural balance of the body. Stabilization splints can bring about neuromuscular balance, removing posterior interference and providing a stable occlusal relationship and an optimization of the centric relationship. The relationship between craniometric posture and TMD has been studied, however, despite the huge number of studies, clinicians and academics still remain unconvinced.

Centric Relationship and Posture

The conclusion is mandatory: 'however, despite the huge number of studies, clinical and academic remain unconvincing.' This always turns out to be a diplomatic way to avoid trouble but if we carefully read the salient points of this extract it seems that everything derives from a sort of balance due to occlusal stability and an exact Mandibular Centric Relationship. But the question that arises is:

«What Centric Relationship are we talking about!!!»
(perhaps the forced terminal or the guided one but no!! we do the myocentric which is more suitable perhaps using TENS.)

Without going into specific topics referred to the reference chapters, we want to highlight the inconsistencies encountered in such important statements of correlation between Centric Relationship and Posture. We report a clinical case already presented in the chapter 'Conclusions on the status quo in the logic of medical language regarding the masticatory system' because it is very relevant to the topic 'Masticatory correlation' which highlights the discrepancy between a manual Centric Relation obtained intraoperatively to fix the mandibular and condylar bone structures in orthognathic surgery and the spatial position called Neuro Evoked Centric Relationship obtained through Transcranial Electric stimulation of the trigeminal roots. Figure 1a shows the spatial position of the jaws after orthognathic surgery in which the positions are established through a manual method of 'Centric Relationship'. The surgeon has no other means than the manual mandibular positioning procedure. Despite bilateral edentulism, which he would face after a few months, the patient was considered to be in excellent occlusal stability. The previous chapters demonstrated that after performing the trigeminal reflexes, the patient's masticatory system was far from intact. In figure 1b an enlarged detail of the incisal area to visualize the mandibular incisal line moved towards the left side of the patient while in figure 1c we see a spatial symmetrization of the mandible (moving towards the right side of the patient) using a "Neuro Evoked Centric Registration" through transcranial electrical stimulation of the trigeminal roots (_bRoot-MEPs)

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  Figure 1a: Patient discharged from the orthognathic surgery department

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  Figure 1b: Mandibular spatial position misalignment

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  Figure 1c: Mandibular position alignment after 'Neuro Evoked Centric position'

In conclusion, at this point the problem is no longer the correlation between posture and occlusal stability but the correlation between the Centric Relation and occlusal stability because this relationship is the primus movens of the whole pathophysiological phenomenon and if we are not sure of the assertions we cannot go beyond .

«Be careful, therefore, to use the term 'correlation' between Centric Relation and Posture or Occlusal stability and Posture.»

Another recent study Inchingolo et al. asserts the following: the cranial surface electromyography allows the evaluation of the occlusal state and the quantification of the neuromuscular postural balance, thus understanding the dental occlusion from a functional point of view. It therefore represents a diagnostic revolution because it allows you to see what until now was only perceptible by palpation, and therefore not quantifiable. A meta-analysis on the use of sEMG to evaluate the relationships between masticatory muscles and postural muscles found that the correlation between the masticatory system and the muscle activity of other parts of the body can be detected experimentally using sEMG, but this correlation has little clinic relevance . However, Julià-Sánchez et al. found that dental occlusion affects the biomechanical and viscoelastic properties of masticatory and postural muscles using the MyotonPRO® system. The influence of the occlusal state on stability was also demonstrated in an article by Heit et al. who found a significant increase in balance at rest rather than at maximal intercuspidation. These results are consistent with previous studies that used sEMG to measure both the muscle balance of the masticatory muscles and its influence on the activity of some postural muscles. A substantial reduction in resting postural muscle activity (sternocleidomastoid, erector spinae, and soleus) was found in participants with dental malocclusions after balancing with a bite.

Simmetry

When we speak of neuromotor balance in reference to electromyographic procedures, terms such as synchronicity and symmetry are implicitly evoked. Side-to-side symmetry of EMG motor unit discharges is a complex procedure to record and interpret. Many factors come into play and not only the level of muscle contraction but also the type of electrode and electromyographic device used. If the concept of symmetry is focused referring to interferential EMG pattern then the situation is further complicated by the spatio-temporal summation of the motor units which discharge asynchronously and at variable frequency. This can lead to collisions and cancellations of the recordable potential on the skin. The only way to be able to extrapolate a significant data is the Fourier analysis and the Wavelet model which, with the usual limitations of indeterminacy and measurement uncertainty already discussed in other chapters (K_brain), tries to decompose the already complex signal due to its nature biochemistry and extrapolate information on biophysics. But the question that arises is:

«Are we sure we are dealing with an 'Asymmetry'?»
(.... are we talking about a functional or organic asymmetry?)

Even with regard to this very delicate point of neuromuscular balance and symmetry, without going into specific topics referred to the reference chapters, we would like to highlight the inconsistencies encountered in statements of the 'symmetry/asymmetry' type between sides of the interferential EMG pattern. Figure 2a shows an interferential EMG trace (right and left masseter, upper and lower trace respectively) in which, obviously, an evident asymmetry can be recognized already at a first visual approach without further mathematical decompositions. In figure 2c, on the other hand, one can also appreciate, in other patient, a good symmetry of the sides.

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  Figura 2a: Functionally asymmetric interference EMG pattern

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  Figura 2b:Motor evoked potential of the trigeminal roots

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  Figura 2c: Functionally symmetrical interferential EMG pattern

Well, these two asymmetry/symmetry data (figure 2a and 2c) have no clinical significance because they are functional characteristics of the system which, as we anticipated, are unstable and modulated by other internal and external components of the system itself. The clinical and laboratory aspect would change drastically if the interferential EMG pattern content in Figure 2a and 2c were normalized to the content of the Motor Evoked Potential of the trigeminal roots (Figure 2b) - same electrode arrangement). In this way, given the perfect amplitude symmetry of the Root-MEPs, we can irrefutably state that the EMG tracing in figure 2a corresponds to a state of 'Asymmetry' while that of figure 2c to a state of 'Symmetry'. If the _bRoot-MEPs were resulted asymmetric we would have had to speak of organic and functional symmetry and not of asymmetry. We should have looked for the causes, perhaps of measurement errors or verifying the extent of the asymmetry of the motor evoked potentials, but the concept is that we cannot give value to a functional peripheral datum without knowing the organic datum.

«Beware of using the term 'Asymmetry' too casually»
(We can say that by throwing a die we have ${\frac {1}{36}}$ of probability that a number from 1 to 6 comes out but we must be sure that the die has 6 sides and that the numbers are from 1 to 6)

We could go on and on but we prefer to deal with the clinical case of our patient 'Balancer'

3rd Clinical Case

As anticipated we will resume the same diagnostic language presented both for the patient Mary Poppins and for the 'Bruxer' patients so that it becomes an assimilable and practicable model, we will try to superimpose it on the present clinical case called 'Balancer'.

The subject, a 60-year-old man undergoing prosthetic rehabilitation about 10 years earlier, had begun to report masticatory difficulties and specifically a sort of decrease in muscle strength on the right side and slowing down of the masticatory cycle. After an unquantified period of time, the patient also felt a difficulty in both static and dynamic balance. Reporting these disturbances to his dentist, he was proposed a makeover of the prosthetic rehabilitation. The clinical situation did not change, on the contrary the postulated disturbances increased leading the dentist to a new prosthetic rehabilitation this time following the postural methods through a synergism between pedanometric examinations and centric recordings. Having reached our observation, we immediately subjected the patient to our diagnostic process which is, as usual, represented in the form of 'Contexts'.

Meaning of the dental contexts

As already mentioned but it should be emphasized, in the dental field we will have the following sentences and statements to which we give a numerical value to facilitate the treatment, or $\delta _{n}=[0|1]$ where $\delta _{n}=0$ it indicates 'normal' and $\delta _{n}=1$ anomaly and therefore a positive report:

$\delta _{1}$ Negative TMJ MRI Report in Figure 3, $\delta _{1}=0\longrightarrow$ Normal, Negative Report

$\delta _{2}$ Negative axiographic report for right condylar tracing in Figure 4, $\delta _{2}=0\longrightarrow$ Normality, negative report

$\delta _{3}$ Negative axiographic report for left condylar tracing in Figure 5,$\delta _{3}=0\longrightarrow$ Normality, negative report.

$\delta _{4}$ Slightly asymmetric EMG interference pattern in Figure 6, $\delta _{4}=1\longrightarrow$ Abnormality, Positivity Report

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  Figure 3: $\delta _{1}$ MNR of the right TMJ in a coronal plane

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  Figura 4: $\delta _{1}$ Right paraocclusal axiography

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  Figure 5: $\delta _{1}$ Left paraocclusal axiography Left paraocclusal axiography

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  Figure 6: $\delta _{1}$ EMG Interference Pattern

Meaning of the neurophysiological contexts

In the neurological context we will therefore have the following sentences and assertions to which we give a numerical value to facilitate the treatment and that is $\gamma _{n}=[0|1]$ where $\gamma _{n}=0$ it indicates 'normality' and $\gamma _{n}=1$ 'abnormality and therefore positivity of the report:

$\gamma _{1}=$ Absence of jaw jerk in Figure 7   $\gamma _{1}=1\longrightarrow$ Abnormality, positive report. In clinical situations of occlusal disharmony we could find ourselves faced with situations of amplitude asymmetries that even border on an absence of the jaw jerk but in this clinical case the contextual asymmetry of the interferential EMG could mean nothing. We continue in the neurological context to verify the responses of other trigeminal electrophysiological tests.

$\gamma _{2}=$ Latency asymmetry of the electrical Silent Period on the right masseter in Figure 8,   $\gamma _{2}=1\longrightarrow$ Abnormality, positive report

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  Figure 7: $\gamma _{1}=$ Jaw Jaw jerk in maximum intercuspidation

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  Figure 7: $\gamma _{2}=$ Latency asymmetry of the masseter electric Silent Period

$\tau$ Demarcator of diagnostic coherence

As we have already described several times in the previous chapters, the '$\tau$' is a representative clinical specific weight, complex to research and develop because it varies from discipline to discipline and for pathologies, indispensable in order not to collide logical statements $\Im _{o}$ and $\Im _{n}$ in diagnostic procedures and fundamental to initialize the decryption of machine language code. In essence, it allows you to confirm the coherence of one assertion $\Im \cup \{\delta _{1},\delta _{2}.....\delta _{n}\}$ against another $\Im \cup \{\gamma _{1},\gamma _{2}.....\gamma _{n}\}$ and vice versa, giving greater weight to the seriousness of the reports and to the choice of the appropriate context.

The weight of the $\tau$ demarcation, therefore, gives greater significance to the more serious assertions in the clinical context from which they derive and therefore beyond the greater or lesser positivity of the assertions $0\leq \delta _{n}\leq 1$ or $0\leq \gamma _{n}\leq 1$ which in any case are always verified and respected, these must be validated on the basis of the clinical severity intrinsic considering the average of the assertions ${\bar {\delta _{n}}}$ and ${\bar {\gamma _{n}}}$ for one $\tau =[0|1]$ where $\tau =0$ it indicates 'low seriousness' while $\tau =1$ 'high seriousness'.

Summarizing in our case 'Balancer' we therefore have:

$\Im _{o}\cup ({{\bar {\delta }}_{n})}\tau _{o}+\Im _{n}\cup ({{\bar {\gamma }}_{n})}\ \tau _{n}=\Im _{d}$

where

${{\bar {\delta }}_{n}}=$ average of the value of clinical statements in the dental context and therefore ${{\bar {\delta }}_{n}}=0,25$ which derives from positive EMG asymmetry data with respect to the total number and therefore $(1/4)$

${{\bar {\gamma }}_{n}}=$ average of the value of clinical statements in the neurological context and therefore ${{\bar {\gamma }}_{n}}=1$ as we have two positive reports out of 2 total

$\tau _{o}=0,25$ signaling low severity of the dental context

$\tau _{n}=1$ signaling high severity of the neurological context

where the coherence demarcator $\tau$ will define the diagnostic path as follows

$\Im _{o}\cup ({{\bar {\delta }}_{n})}\tau _{o}+\Im _{n}\cup ({{\bar {\gamma }}_{n})}\ \tau _{n}=\Im _{d}$

$\Im _{o}\cup ({0,25)}\times 0+\Im _{n}\cup ({1)}\times 1\ \longrightarrow \Im _{d}=\Im _{n}$

As can be seen in our clinical case 'Balancer' we have a diagnostic prevalence towards the neurological context which indicates the neurological component as a diagnostic path.

«Attention, then, also to the term asymmetry»
(because we can confuse a trivial Occlusal-Postural asymmetry with a serious neurological damage of a structural type)

Consequently, we can concentrate on the interception of the tests necessary to decrypt the machine language code that the CNS sends to the outside converted into verbal language which apparently would seem to concern a sort of postural disorder of the dental malocclusion type, due to the incongruous rehabilitation prosthetic. If on the one hand there may be an asymmetry of the interferential EMG of the masseters due to a prosthetic occlusal imbalance, on the other hand such an evident asymmetry of the jaw jerk and the silent period cannot be justified.

Bibliography & references