Trigemino-vagal reflex to assess palatoglossal status in a patient with vestibulocochlear Schwannoma

 A patient with vestibular schwannoma required intraoperative neuromonitoring (here). Symptoms were one year of right hearing loss, right face numbness, numbness in the inner right oral cavity until the pharynx. Motor movements are normal for all cranial nerves (6th, 7th, 11th, 12th).

PREOPERATIVE STUDY

Facial nerve motor neurography (with simultaneous recording from Orbicularis oculi, Orbicularis oris and nasalis muscles showed reduced CMAP amplitude with preserved velocities in the right side all investigated muscles.

Blink reflex (supraorbital nerve - V to Orbicularis oculi - VII) showed delayed R1 in the right side with conserved R2 morphology in both sides when stimulation was applied to the right side and normal R1 with reduced amplitude of R2 components when stimulation was applied to the left side.

There were signs of mild facial nerve neuropathy (“axonal” or neurapraxia) in the right side.Blink reflex showed abnormal afferent component (5th) in the right side.There are objective findings of 5th and 7th nerves involvement. The IONM protocol will include corticogeniculate MEP (Co-MEP), SSEP, mapping of cranial nerves and trigemino-facial monosynaptic reflex (R1).

INTRAOPERTIVE NEUROMONITORING   Procedure and Results

 

Before the anaesthesia nine “10-20” scalp locations were marked (Fpz, Cz, Cz’, C3, C4, C1, C2, C3´and C4´). In the operating room and previous to neuronavigation and fixation moment, in dorsal decubitus position, with total anesthesia and orotraqueal intubation, we introduced hook wires electrodes in both palatoglossus muscles, both orbicularis oculi, both orbicularis oris, both masseter, right nasalis, right mentalis, both hypoglossus, both APB, left AH and left TA muscles.

Modalities: Spontaneous EMG, transcortical MEP, corticogeniculate MEP (Co-MEP), SSEP, blink reflex, monopolar and bipolar cranial nerves mapping (trigeminal –masster, facialis –orbicularis oculi, nasalis, orbicularis oris, mentalis, vagus –palatoglossus, hypoglossus –tongue).

 

MEP: “train of five” technique from C2-C1

SSEP: from tibialis nerve and median nerve, recordings from Cz´-Fpz and C4´-Cz’ channels

Co-MEP: were obtained from orbicularis oris and mentalis in the right side, from C3-Cz and C4-Cz

Blink reflex: was useful during the entire procedure. We used a train of 6 pulses (right side) and 3 pulses (left side) with 149uS duration and a frequency of 0.5Hz (rabndomness of 10-20%). Intensity was 102 V in the right supraorbital nerve and 50 V in the left supraorbital nerve.

Scalp EEG from cork screw electrodes: 6 channels.

BAEP

At the end of the surgery we performed zygomatic nerve – palatoglossus (V-X) reflex.

 

Results:

MEP, SSEP and CoMEP modalities showed similar signals at the end of the surgery.

Mapping techniques were useful to localization of the hypoglossus, vagus and facialis cranial nerves with thresholds low up to 3-5mA for monopolar stimulation (not more than 12 mA) and 0,29-0,43mA for bipolar facialis mapping.

Raw EMG:

Incidence: In two occasions we observed spontaneous discharges of “A train” first time in mentalis muscle (less than 15 seconds duration) and the second time in bursts of less than 2 seconds (during less than 10-15 seconds) in orbicularis oris muscle. “B train” was seen in one occasion during less than 10 seconds. These discharges were rapidly communicated and we assumed they corresponded to manipulation or “debulking” near the facial nerve.

Blink reflex: showed delayed latency in the right side, but it was the modality used during the entire surgery and it show good responses even during spontaneous neuromyotonic changes assuming that the nerves were intact.

Trigemino-vagal reflex: at the end of the surgery a new modality was set in a protocol to assess the palatoglossal status. The reflex was observed with a latency of more than 20 ms in both palatoglossal muscles (in the picture the name of the channel is LGF and RGF) but no record was seen from hypoglossus muscles (tongue) or masseter muscle.

 

Conclusion:

The tumor was removed in proportion of 50-60%. We assumed that there would be no long-lasting new neurological deficits in the analyzed and monitored cranial nerves.

The patient had postoperative diplopia, followed the examinator finger to both sides, facial and hypoglossal nerves looked to be with no new deficits. 

MION Synapse Iceland. Branch of a Spanish Headquarter or Private Limited Company

There are many types of companies and business options in Iceland (here).

Informal Group of MION Synapse International (IGMSI) is a multidisciplinary team formed by neurosurgeons and clinical neurophysiologists from Spain, Romania and Iceland which has as the main objective the intraoperative neuromonitoring (IONM), a technique and a mandatory tool in operating room theaters to benefit patients submitted to certain surgical procedures, namely any surgery where there is risk to the nervous system.

MION Synapse initiative started in Romania in May 2019 and a formal limited company would be organized in Barcelona, Spain during the next three months.

Branches of Foreign Companies

Branches of limited companies are registered with the Internal Revenue in the Register of Enterprises department and the head office must file the following documents:

• A copy of the articles of association of the head office.
• The incorporation certificate of the head office.
• A written commitment from the head office to abide by Icelandic law and Icelandic jurisdiction.
• A letter of representation for the branch manager together with documentation that the branch manager meets the requirements as to residency, citizenship and solvency.
• The Financial Statements of the head office for the preceding year.
• A registered branch must have a name which includes the name of the foreign limited company.
• 
  
• Note that documentation filed with the Icelandic authorities must be submitted in certified Icelandic translation.

The registration fee is ISK 256,000.

Private Limited Companies

Rules for private limited companies are simpler than for the public ones. The minimum stock required is ISK 500,000. Other minimum requirements are to have one founder, one shareholder, and one director (with one deputy) in cases where shareholders are four or less. There is no obligation to have a manager.

The Minister of Commerce can grant an exemption from the otherwise general principle that the majority of the board of directors and the general manager of a limited company must be domiciled in Iceland or in a country within the European Economic Area or OECD.

Informal Group MION Synapse International

En una sociedad con servicios para la salud cada vez mas avanzados, la neurofisiologia clinica y la monitorizacion intraoperatoria neurofisiologica (MION) se convierten en instrumentos obligatorios para el acto medico de calidad enfocado al paciente con daño de nervio periferico o sistema nervioso central.

MION Synapse es una sociedad de responsabilidad limitada, una sociedad mercantil en la cual la responsabilidad está limitada al capital aportado (sociedad de capital). La normativa para una S.L. se encuentra regulada en el texto refundido de la Ley de Sociedades de Capital, aprobado por Real Decreto Legislativo 1/2010, de 2 de julio. El estatuto de MION Synapse S.L. está recogido en escritura pública y se va a inscribir en el Registro Mercantil.

MION Synapse S.L. tiene como objetos de actividad:

1. La realización de toda clase de actividades relacionadas a la especialidad médica de Neurofisiología Clínica (Real Decreto 2015/1978, 15 de Julio, Referencia: BOE-A-1978-22162) en el ámbito de la Sanidad Pública o Privada.

2. Actividad de monitorizaciones intra-quirúrgicas según ANEXO de la orden SCO/2617/2008, de 1 de septiembre, por la que se ha aprobado y se ha publicado el programa formativo de la especialidad de Neurofisiología Clínica (BOE 224 de 16/09/2008 Sec 3 Pag 37921 a 37925, Parágrafo 6.4.1.6., Literas a, b, c y d )