Incidental durotomy resulting in a postoperative lumbosacral nerve root with eventration into the adjacent facet joint: illustrative cases

BACKGROUND

Radicular pain after lumbar decompression surgery can result from epidural hematoma/seroma, recurrent disc herniation, incomplete decompression, or other rare complications. A less recognized complication is postoperative nerve root herniation, resulting from an initially unrecognized intraoperative or, more commonly, a spontaneous postoperative durotomy. Rarely, this nerve root herniation can become entrapped within local structures, including the facet joint. The aim of this study was to illustrate our experience with three cases of lumbosacral nerve root eventration into an adjacent facet joint and to describe our diagnostic and surgical approach to this rare complication.

OBSERVATIONS

Three patients who had undergone lumbar decompression surgery with or without fusion experienced postoperative radiculopathy. Exploratory revision surgery revealed all three had a durotomy with nerve root eventration into the facet joint. Significant symptom improvement was achieved in all patients following liberation of the neural elements from the facet joints.

LESSONS

Entrapment of herniated nerve roots into the facet joint may be a previously underappreciated complication and remains quite challenging to diagnose even with the highest-quality advanced imaging. Thus, clinicians must have a high index of suspicion to diagnose this issue and a low threshold for surgical exploration.

Clinical profile and magnetic resonance imaging characteristics of Duane retraction syndrome

PURPOSE

To describe the clinical profile and magnetic resonance imaging findings of the brain in Duane retraction syndrome (DRS) and determine whether there is an association between clinical presentation and magnetic resonance imaging (MRI) brain characteristics.

MATERIALS AND METHODS

This was a cross-sectional study done at a tertiary care center in South India. We recruited and analyzed the clinical characteristics of 54 patients with DRS. MRI of the brain with fast imaging employing steady-state acquisition (FIESTA) was performed in 41 cases, and the cisternal segment of the sixth nerve was studied. Statistical analysis was done to determine any association between the radiological and clinical features.

RESULTS

Type 1 DRS was predominant, followed by Type 3 DRS and Type 2 DRS. 9.3% of cases were bilateral and 11.1% were familial. Orthotropia was most common, followed by esotropia and exotropia. The MRI brain showed the absence of the cisternal part of the sixth nerve on the affected side in 82% of Type 1 and 75% of Type 3 unilateral DRS. Both the abducens nerves were visualized in 19.5% of the patients with unilateral DRS. There was no statistically significant association between MRI brain findings and the clinical features.

CONCLUSIONS

MRI brain with FIESTA shows absent or hypoplastic sixth nerve in most cases of Type 1 and Type 3 DRS. However, around 20% of DRS cases may show the presence of the cisternal part of the sixth nerve. Hence, clinicians must be cautious when ruling out DRS on the basis of MRI brain findings. Although aplasia of the sixth nerve is the most frequent MRI finding, it may not be the sole etiologic factor.

Magnetic resonance imaging findings of isolated abducent nerve palsy induced by vascular compression of vertebrobasilar dolichoectasia

If the origin of isolated abducent nerve palsy cannot be found on neuroradiological examinations, diabetes mellitus is known as a probable cause; however, some cases show no potential causes of isolated abducent nerve palsy. Here, we report a 74-year-old male who suffered from diplopia due to isolated left abducent nerve palsy. Magnetic resonance angiography and fast imaging employing steady-state acquisition imaging clearly showed a dolichoectasic vertebrobasilar artery compressing the left abducent nerve upward and outward. There were no abnormal lesions in the brain stem, cavernous sinus, or orbital cavity. Laboratory data showed no abnormal findings. We concluded that neurovascular compression of the left abducent nerve might cause isolated left abducent nerve palsy. We observed him without surgical treatment considering his general condition with angina pectoris and old age. His symptom due to the left abducent nerve palsy persisted. From previous reports, conservative treatment could not improve abducent nerve palsy. Microvascular decompression should be considered for abducent nerve palsy due to vascular compression if patients are young, and their general condition is good. We also discuss interesting characteristics with a review of the literature.

Facial nerve atrophy in patients with amyotrophic lateral sclerosis: Evaluation with fast imaging employing steady-state acquisition (FIESTA)

BACKGROUND

In amyotrophic lateral sclerosis (ALS), motor neurons in the brainstem markedly deplete, whereas sensory neurons are less severely affected.

PURPOSE

To determine whether facial nerve (FN) measurement on 3D fast imaging employing steady-state acquisition (FIESTA) is useful for ALS diagnosis.

STUDY TYPE

Retrospective.

SUBJECTS

Fifteen ALS patients and 16 controls.

FIELD STRENGTH/SEQUENCE

3T FIESTA MR.

ASSESSMENT

The cross-sectional area of the FN and cochlear nerve (CN) were measured, and the FN/CN ratio (FCR) was assessed. For qualitative assessment, the FN cross-sectional area was compared with that of the CN and the following scores were assigned: score 1 (large), the FN is larger than the CN; score 2 (almost equal), the size difference between the FN and CN is within 10%; score 3 (small), the FN is smaller than the CN (10-50%); score 4 (significantly small), size of the FN is less than half the size of the CN.

STATISTICAL TESTS

The differences in FCR between the ALS patients and the controls were tested using the Wilcoxon Mann-Whitney U-test. For the qualitative and quantitative assessments, we performed a receiver operating characteristic analysis for the diagnosis of ALS with an abnormal finding as score 3 or 4.

RESULTS

The mean FCR was significantly smaller for ALS patients (0.71 ± 0.17) than for controls (0.95 ± 0.08) (P < 0.001) and the area under the curve was 0.93. When an FN score was 3 or 4, indicative of FN atrophy, the sensitivity and specificity values of FIESTA for discriminating ALS patients from controls were 93.3% (14/15) and 90.0% (18/20), respectively.

DATA CONCLUSION

The FN atrophy revealed on FIESTA, which may reflect lower motor neuron impairment in ALS, allowed us to distinguish ALS patients from controls with a high degree of accuracy.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:757-766.