Somatosensory evoked potential for detection of subclinical neuropathy in Egyptian children with acute lymphoblastic leukaemia

Clinical utility of complex assessment with evoked potentials in acute lymphoblastic leukemia survivors: comparison of various treatment protocols

BACKGROUND

One of the greatest success of pediatric hematology is a prominent improvement of survival in acute lymphoblastic leukemia (ALL). Therefore, special attention needs to be paid to long-term side effects of the treatment such as neurotoxicity. One of the few diagnostic methods that allow an objective assessment of sensory systems are evoked potentials (EP).

METHODS

The analyzed group consisted of 167 ALL long-term survivors, aged 4.9-28.4 years, without auditory, visual and sensory deviations. Patients were treated with New York (NY, n = 35), previous modified Berlin-Frankfurt-Münster (pBFM, n = 47) and BFM95 (n = 85) protocols. In order to assess the impact of radiotherapy on recorded EP, a joint analysis of NY and pBFM groups was performed. The control group consisted of 35 patients, aged 6-17 years. The analyzed patients underwent a complex assessment with visual EP (VEP), somatosensory EP (SEP) and brainstem auditory EP (BAEP) in accordance with current standards.

RESULTS

ALL treatment contributed to the shortening of wave I latency (1.59 vs 1.90, P = 0.003) and prolongation of I-III (2.23 vs 2.04, P = 0.004) and I-V (4.57 vs 4.24, P = 0.002) interwave latencies of BAEP. A significant effect was also noticed in P100 (106.32 vs 101.57, P < 0.001) and N135 (151.42 vs 138.22, P < 0.001) latencies of VEP and N18 amplitude (3.24 vs 4.70, P = 0.007) and P25 latency (21.32 vs 23.39, P < 0.001) of SEP. The distribution of abnormalities between protocols was similar in BAEP (NY - 68.6%, pBFM - 61.7%, BFM95-69.4%, P = 0.650), VEP (NY - 68.6%, pBFM - 42.5%, BFM95-58.3%, P = 0.053) and significantly different for SEP (NY - 62.9%, pBFM - 36.2%, BFM95-53.0%, P = 0.045). The harmful effect of radiotherapy was most clearly marked in numerous disturbances of SEP parameters.

CONCLUSIONS

The presented analysis indicates a high frequency of subclinical abnormalities in EP regardless of the analyzed protocol. To our knowledge current study is the largest and one of the most complex research examining the role of EP in ALL patients. The obtained results indicate the possibility of using a single, objective and non-invasive measurement of EP in ALL survivors in order to stratify the risk of developing sensory abnormalities in adulthood.

Factors Associated With Inadequate Intraoperative Baseline Lower Extremity Somatosensory Evoked Potentials

PURPOSE

Intraoperative neurophysiologic monitoring involves the use of various modalities, including somatosensory evoked potentials (SEP), to assess the integrity of the at-risk nervous system during surgeries. Reliable baseline tracings are important because they are data against which future tracings are compared to detect potential injury. In some cases, adequate baselines may be difficult to achieve. Therefore, we analyzed several patient-specific factors to determine which variables are associated with inadequate intraoperative SEP baseline signals.

METHODS

This is a single-center, retrospective chart review of 631 consecutive patients who underwent spine or cranial surgeries between 2010 and 2011. Variables analyzed included age, glucose levels, diabetes mellitus type 2, hypertension, hyperlipidemia, height, weight, sex, smoking, preexisting neurologic conditions, surgical history, lower extremity edema, and neurologic examination findings. Association between these patient factors and baseline lower extremity SEP signals were analyzed.

RESULTS

Height, weight, neurologic deficits, lower extremity edema, and history of neurologic disease are each associated with inadequate baseline lower extremity SEPs after controlling for confounding variables. Baseline signals were able to be acquired in 94.1% of patients.

CONCLUSIONS

Adequate baselines are paramount for successful intraoperative neurophysiologic monitoring. However, certain patient-specific factors are associated with inadequate baseline SEP signals. Physical examination findings and a detailed chart review can be done to identify these factors and guide expectations during monitoring. Further research related to patient-specific factors amenable to modification can further improve our capacity to protect the nervous system during surgery.