RESEARCH STUDY ASSESSMENT – STRENGTHS & WEAKNESSES
Antibiotics for otitis media with effusion in children (Venekamp, et al., 2016)
Strengths: This was a randomized control trial (RCT). Appropriate method of group selection was followed.
Weaknesses: As the ages of the study trial participants vary widely, there is a risk of bias. There is a risk of outcome likely to be influenced by antibiotic resistance.
Prognostic factors and risk group analysis in follicular carcinoma of the thyroid (Shaha, Loree, & Shah, 1995)
Strengths: Study clearly outlines the prognostic factors with univariate and multivariate analysis. Stratification of data has been done to reduce risk of concealment bias.
Weaknesses: There is no reference to thyroid carcinoma confounders in the study, which could have negatively impacted the usefulness of stratification of data mentioned above.
Prevention and treatment of post-partum depression: a controlled randomized study on women at risk (Chabrol, et al., 2002)
Strengths: Randomized control nature of the study.
Weaknesses: People have been lost to follow up during the course of the study and this could’ve led to increase in bias due to loss to follow up. Sampling error is very likely as there are more mothers with major depression in the control group vis-à-vis those in the treatment group.
Risk factors for early onset neonatal group B streptococcal sepsis: case-control study (Oddie & Embledon, 2002)
Strengths: Large sample size; study spread over considerable time interval; sample from a large area.
Weaknesses: While considering risk factors, proper weightage is not given to confounding factors e.g., study participants being more susceptible to infection in the winter months than in summer. Another example is where age of the baby makes them more susceptible to infections i.e., the younger the baby is, the more susceptible they are.
ACTIVITY DONE FOR INTERPRETING 95% CONFIDENCE INTERVAL (CI)
Based on online resource education, random articles were opened to understand and interpret 95% CI.
(Zilberberg, Shorr, Vazquez-Guillamet, & Kollef, 2014)
Based on online resource education, random articles were opened to understand and interpret 95% CI. In the above study (Zilberberg, Shorr, Vazquez-Guillamet, & Kollef, 2014), 95% CI is interpreted as a two to four-fold increase in risk compared to patients that have been on the right antibiotic from the start. Confidence interval crosses 1, therefore no effect.
LITERATURE REVIEW – MONITORING IN ACDF PROCEDURES
The incidence of iatrogenic nerve injury resulting in permanent damage to recurrent laryngeal nerve is high in neck procedures including spinal procedures i.e., Anterior Cervical Decompression & Fusion (ACDF). This review aims to identify what conclusions regarding use of MEPs to vocal cords can be reached from these studies, in relation to use of MEPS in anterior spine surgeries with its outcomes and risks. Currently, there is no enough literature to review regarding recording of MEPs from vocal cords. Therefore, further studies using different MEP recording techniques are required to validate finding and to confirm the reliability of MEP recording from vocal cords.
Intraoperative monitoring (IOM) has been in use so as to reduce the occurrence of iatrogenic neurological damage during spinal surgery. Neuromonitoring has been in use for the last thirty to forty years so as to check for the functionality of the RLN during spine, thyroid and other procedures around neck (Hermann et al., 2004). The other uses of IOM are to locate smaller more intricate neural structures so as to avoid damage to the same which can have severe repercussions postoperatively. IOM thus can have several modalities through which the monitoring can take place. TheseOffice2 include Somatosensory Evoked Potentials (SSEP), Motor Evoked Potentials (MEP), Electroencephalography (EEG), Electromyography (EMG), Visual Evoked Potentials (VEP) and Brainstem Auditory Evoked Potentials (BAEP) (Kim et al., 2013).
The use of Intraoperative neurophysiological monitoring (IONM) during lumbar and thoracic spine surgery have been a routine procedure for a long time, however its use in cervical spine surgery is relatively new Epstein, Danto and Nardi (1993); Gokaslan et al. (1970; May, Jones and Crockard (1996); Papastefanou et al, (2000); Sebastin et al. (1997). Accordingly, the use of SSEP during cervical spine surgery while sensitive enough for the detection of potential neurological damage that may be caused due to the operative procedure, trauma due to mechanical force, ischaemia or hypotension Epstein, Danto and Nardi (1993); May, Jones and Crockard (1996); Papastefanou et al, (2000); Sebastin et al. (1997); Bouchard, Bohlman and Biro (1996), has been found to be quite unreliable due to its reduced amplitudes and poor waveforms. This can be instanced in cases such as tumour of the spinal cord, severe myelopathy, peripheral neuropathy, where both the use of and monitoring using was quite challenging (Schwartz et al., 1998). This may be so as the mediation of SSEP occurs through the dorsal column fibres (Chiappa & Hill, 1997), along with the smaller contribution from the ascending fibres that is lateral in location (Levy & York, 1984). However, SSEP finds most use in the monitoring of the global spinal cord function, as the results are directly deduced without the need for measurements as put forth by the potentialOffice3 . On the other hand, they may prove to be barely useful where the functional defects relating to motor activity that may be the direct result of spinal column injury (anterior), nerve decompression or faulty instrumentation. In light of this, there emerges a need to adopt other IONM modalities especially during cervical spine surgery.
In the case of cervical spinal surgery the other available potentials include the MEP, Dermatomal Evoked Potentials (DEP) and triggered EMG (Geller & Najm, 1999) and (Schwartz, 1996). For MEPs, the transcranial type has been found to measure the corticospinal tract directly with respect to motor activity thereby assessing the criticality of detecting potential motor deficits during anterior cervical spine surgery. Therefore, even though there exists a conflicting view as to how to effectively use MEP, it is fast gaining importance for the benefits of using these potentials in brain and spine surgeries (Bose et al., 2004; Calancie et al., 1998; Deletis et al., 2001; Gugino et al., 1997; Gugino & Schwartz, 2001).
Therefore, IONM has been a standard of care for preventing or reducing potential iatrogenic damage to neurological structures during cervical procedures. The electrical signals recorded from extremities through stimulation of motor cortex of brain (MEP) are recorded before the commencement of the procedure and set as baseline. The responses are checked real time during the procedure and compared with baseline thus any variability to baseline assessed to other factors including haematological or vascular and information is provided to the surgeon who may change the manoeuvre accordingly or adjust instrumentation to avoid irritation(Lemma, 2015) . It can thus be emphasised here that as the major aspect of prevention of nerve damage in spine surgery is the timeliness with which it can be corrected. Therefore, it becomes imperative to develop methods that can enable for the same (Nandoe Tewarie et al., 2007). More recently, in the vocal cord EMG monitoring there has emerged reports on the additional monitoring for RLN. However, the requisites of the same have not been fully understood. With this view, below are discussed Motor evoked potentials as a method of monitoring during anterior cervical spine surgery.
Motor-Evoked PotentialOffice4 (MEP)
Motor-Evoked Potentials (MEPs) is the latest tool in the field of Intraoperative Neurophysiologic Monitoring (IONM). Promising reports of better outcomes following scoliosis procedures in children and juveniles were obtained using Somatosensory Evoked Potential (SEP) monitoring, and there were reports of fewer cases of isolated postoperative motor injuries with no sensory changes (Padberg et al., 1996). According to Jameson, MEP and SEP pathways run through different topographic and vascular regions of the cerebral cortex, brainstem, and spinal cord (Jameson, 2012). Ischemic insults affect MEP pathways more than SEP pathways (Hickey et al., 1995). Rare isolated motor injury with no sensory changes following idiopathic scoliosis procedures was not the only causative factor in the widespread use of MEP monitoring. Operative complexity and increasing surgical volume in the Central Nervous System (CNS) and spine in adults at high risk also propelled the need to assess motor function; MEPs aided in improved decision making intraoperatively in all patient groups. With the advance in different surgical techniques and perioperative management of anaesthesia, surgeries were performed on the aged/injured patients and only a few years back, these surgeries were not even considered for such patients.
As a result, spine and neurological surgeons have been employing MEP monitoring to help prevent surgical intervention from exceeding safe limits of intervention where functional gain is far exceeded by risk and severity of the potential surgical injury (Fehlings et al., 2009). As MEP monitoring, especially during spine surgeries, is more effective in regards to postoperative motor outcome than SEPs, MEP monitoring is highly recommended for many surgeries, e.g. (1) surgical correction of axial skeletal deformity (Pelosi et al., 2002; MacDonald et al., 2003; Minahan et al., 2001; Hsu et al., 2008a), (2) intramedullary spinal cord tumors (Lang et al., 1996; Morota et al., 1997; Sala et al., 2006; Deletis & Sala, 2008), (3) intracranial tumors (Mikuni et al., 2007a; Neuloh et al., 2004; Mikuni et al., 2007b), and (4) CNS vascular lesions (Szelényi et al., 2006; Neuloh & Schramm, 2004a; Sala et al., 2007). Of late, MEPs have been aiding in pre-emptive assessment of outcome in stroke (Shine et al., 2008; Woldag et al., 2006; Nascimbeni et al., 2006) and spinal cord function during thoracoabdominal aneurysm repair (Shine et al., 2008). Along the same lines, authors Romagna et al. (2015), and Puram et al. (2015) evaluated the effects of MEP in the aspect of monitoring vocal cords in such spine surgeries. While Puram et al. (2015) monitored the use of MEP on vocal cords so as to prevent RLN injury in canine models; Romagna et al. (2015) on the other hand evaluated MEP as attached to endotracheal tubes to monitor the vocal cords for surgery in the cerebellopontine angle. Both studies in this regard concluded stating that such monitoring through MEP of the vocal cords were effective to prevent postoperative nerve damage. Considering the predictability of MEP of spinal cord integrity, MEPs to vocal cord study could provide better means of monitoring recurrent laryngeal nerve during ACDF procedures, which is under risk.
Office1Please include literature of each modality and review their effects
Office2There is no mention of number of studies showing variation during surgical procedure. Include data that shows changes to support it is a useful modality for ACDF procedures.
Office3Please comment on the quality of research articles used for review
Office4Include clinical applications and the procedures they have been used for MEPS.