Changes in alpha, theta, and gamma oscillations in distinct cortical areas are associated with altered acute pain responses in chronic low back pain patients

Introduction

Chronic pain negatively impacts a range of sensory and affective behaviors. Previous studies have shown that the presence of chronic pain not only causes hypersensitivity at the site of injury but may also be associated with pain-aversive experiences at anatomically unrelated sites. While animal studies have indicated that the cingulate and prefrontal cortices are involved in this generalized hyperalgesia, the mechanisms distinguishing increased sensitivity at the site of injury from a generalized site-nonspecific enhancement in the aversive response to nociceptive inputs are not well known.

Methods

We compared measured pain responses to peripheral mechanical stimuli applied to a site of chronic pain and at a pain-free site in participants suffering from chronic lower back pain (n = 15) versus pain-free control participants (n = 15) by analyzing behavioral and electroencephalographic (EEG) data.

Results

As expected, participants with chronic pain endorsed enhanced pain with mechanical stimuli in both back and hand. We further analyzed electroencephalographic (EEG) recordings during these evoked pain episodes. Brain oscillations in theta and alpha bands in the medial orbitofrontal cortex (mOFC) were associated with localized hypersensitivity, while increased gamma oscillations in the anterior cingulate cortex (ACC) and increased theta oscillations in the dorsolateral prefrontal cortex (dlPFC) were associated with generalized hyperalgesia.

Discussion

These findings indicate that chronic pain may disrupt multiple cortical circuits to impact nociceptive processing.

Validity of the Hum Test, a Simple and Reliable Alternative to the Weber Test

Objectives:

To compare the diagnostic performance of the Hum Test against the Weber Test using pure tone audiometry (PTA) as the “gold standard” comparator.

Methods:

29 participants with normal hearing of ages 18 to 35 without any history of hearing abnormalities or otologic conditions were enrolled. Subjects underwent three tests (Hum Test, Weber Test, and PTA) across two conditions: with an ear plug in one ear (side randomized) and without ear plugs.

Results:

When examining the ability of the Hum Test to detect simulated conductive hearing loss (CHL), the test had a sensitivity of 89.7% and specificity of 100% with high pitched humming and 93.1% and 100%, respectively, with low pitched humming. The Weber Test had a sensitivity and specificity of 96.6% and 100%, respectively. McNemar’s test demonstrated agreement between the Hum Test, performed with either high pitched ( P = .32) or low pitched ( P = .56) humming, and the Weber Test. Receiver operating characteristic (ROC) curves for the Hum Test (both high and low pitched) and Weber test were compared and demonstrated no statistically significant difference.

Conclusion:

The Hum Test is comparable to the Weber Test with regards to its sensitivity, specificity, and diagnostic accuracy in assessing new onset unilateral CHL in previously normal hearing subjects.

Treatment of Cutaneous Head and Neck Squamous Cell Carcinoma Metastatic to the Parotid Gland

Objectives:

1) Recognize challenges in managing metastatic squamous cell carcinomas (SCC) to the parotid gland. 2) Describe our 5-year experience of treating metastatic SCC of the parotid gland.

Methods:

Retrospective case series of 22 consecutive patients undergoing parotidectomies for treatment of metastatic SCC to the parotid gland between August 2006 and December 2011 at Weill Cornell Medical College. Interventions included parotidectomy and radiation therapy (RT). Outcome measures included complications, survival, and locoregional recurrence.

Results:

Seventy-seven percent of patients were male, with a mean age of 77 years (range 46 - 93 years). Eighteen patients underwent superficial parotidectomy, four received total parotidectomy, and 16 underwent neck dissection. Fifteen patients received post-operative RT, and 1 patient had neoadjuvant radiation 4 months prior to surgery. Median dose of radiation delivered was 6300 cGy at 200 cGy per fraction. Overall 2-year survival was 77.4%, and 2-year disease-free survival was 33.3%. Recurrence rate was 54.5%, with a median time to recurrence of 14 months. The 2-year survival rate was 32% and 80% in patients with positive versus negative margins, respectively ( P = .01). The 2-year survival rate was 56% and 100% in patients with positive versus negative cervical lymph nodes, respectively ( P = 0.03). Five of 6 patients receiving conventional RT developed severe skin toxicity or could not complete treatment; none receiving intensity-modulated radiation therapy (IMRT) developed such complications.

Conclusions:

Positive lymph nodes in neck dissection specimens are an important prognostic factor in treating patients with metastatic SCC to the parotid gland. IMRT is better tolerated compared to conventional RT techniques.

The Role of Intraoperative Facial Nerve Monitoring during Parotidectomy for Benign Parotid Gland Tumors

Objectives:

1) Compare outcomes of parotidectomy with and without electrophysiologist-assisted intraoperative nerve monitoring (IOM) for the treatment of benign parotid gland tumors. 2) Recognize potential benefits of IOM in parotidectomy.

Methods:

Retrospective case control of 151 consecutive patients undergoing parotidectomy for treatment of benign tumors between March 2006 and December 2011 at Weill Cornell Medical College. Interventions included parotidectomy and IOM. Outcome measures included complications from intervention(s).

Results:

Sixty-four percent of patients were female, and the median age at surgery was 57 years (range 17 - 86 years). The majority of patients (70%) had pleomorphic adenomas. One surgeon performed all 81 parotidectomies with IOM (54%), while another surgeon performed the remainder without IOM (46%). IOM use depended on the attending surgeon and was not due to any other factor. Superficial parotidectomies comprised 81% and 70% of surgeries performed with and without IOM, respectively. Temporary facial nerve dysfunction occurred in 10.6% of patients. No statistically significant difference was seen in temporary facial nerve paralysis rates post-operatively between groups with IOM (9.9%) and those without (11.4%) ( P = 0.76). In cases with IOM, electrical mapping and presence of transient nerve irritation did not influence the rate of complications ( P = 0.19).

Conclusions:

Use of IOM does not appear to impact the rate of facial paralysis post-parotidectomy for benign parotid gland tumors. However, IOM may be beneficial in aiding the surgeon in difficult cases, to preserve smaller branches, or when the tumor lies particularly close to the facial nerve.

Anterolateral approach to the lower cervical spine: a step-by-step description

The anterolateral approach is a popular and safe method of exposing the lower cervical spine (levels C3 to T1) for management of cervical spine disease. We present a description of the technique we use in conducting the procedure, a review of the literature, and a retrospective chart review of 30 consecutive patients who underwent cervical spine exposure via a left anterolateral approach. All patients had an uneventful perioperative course, and the two patients who experienced postprocedure symptoms recovered completely within 1 month without treatment.