MR Neurography of Greater Occipital Nerve Neuropathy: Initial Experience in Patients with Migraine

Improved 3D DESS MR neurography of the lumbosacral plexus with deep learning and geometric image combination reconstruction

OBJECTIVE

To evaluate the impact of deep learning (DL) reconstruction in enhancing image quality and nerve conspicuity in LSP MRN using DESS sequences. Additionally, a geometric image combination (GIC) method to improve DESS signals' combination was proposed.

MATERIALS AND METHODS

Adult patients undergoing 3.0 Tesla LSP MRN with DESS were prospectively enrolled. The 3D DESS echoes were separately reconstructed with and without DL and DL-GIC combined reconstructions. In a subset of patients, 3D T2-weighted short tau inversion recovery (STIR-T2w) sequences were also acquired. Three radiologists rated 4 image stacks ('DESS S2', 'DESS S2 DL', 'DESS GIC DL' and 'STIR-T2w DL') for bulk motion, vascular suppression, nerve fascicular architecture, and overall nerve conspicuity. Relative SNR, nerve-to-muscle, -fat, and -vessel contrast ratios were measured. Statistical analysis included ANOVA and Wilcoxon signed-rank tests. p < 0.05 was considered statistically significant.

RESULTS

Forty patients (22 females; mean age = 48.6 ± 18.5 years) were enrolled. Quantitatively, 'DESS GIC DL' demonstrated superior relative SNR (p < 0.001), while 'DESS S2 DL' exhibited superior nerve-to-background contrast ratio (p value range: 0.002 to < 0.001). Qualitatively, DESS provided superior vascular suppression and depiction of sciatic nerve fascicular architecture but more bulk motion as compared to 'STIR-T2w DL'. 'DESS GIC DL' demonstrated better nerve visualization for several smaller, distal nerve segments than 'DESS S2 DL' and 'STIR-T2w DL'.

CONCLUSION

Application of a DL reconstruction with geometric image combination in DESS MRN improves nerve conspicuity of the LSP, especially for its smaller branch nerves.

Generalized Extension of Referred Trigeminal Pain due to Greater Occipital Nerve Entrapment

We report a very rare case of referred pain caused by greater occipital nerve (GON) entrapment, inducing spontaneous pain in the whole body as well as in the trigeminal nerve region of the face and head. It has already been reported that entrapment of the GON can induce referred pain in the ipsilateral limb as well as the ipsilateral hemiface. A 42-year-old female patient presented with chronic pain in her gums, jaw angle, submandibular region, retro-auricular suboccipital, and temporo-occipital vertex that had been ongoing for four years. As the patient's head pain and facial pain became severe, severe spontaneous pain occurred in the arm, waist, and both lower extremities. This patient's pain in the occipital and neck, spontaneous pain in the face, jaw, and whole body improved with decompression of the GON. Anatomical basis of pain referral to the facial trigeminal area caused by chronic GON entrapment is convergence of nociceptive inflow from high cervical C1-C3 structures and trigeminal orofacial area in the dorsal horn of the cervical spinal cord from the C2 segment up to the medullary dorsal horn (MDH). The major afferent contribution among the suboccipital and high cervical structure is mediated by spinal root C2 that is peripherally represented by the GON. Chronic noxious input from GON entrapment can cause sensitization and hypersensitivity in second order neurons in the trigeminocervical complex (TCC) and MDH in the caudal trigeminal nucleus and high cervical cord. Generalized extension of referred pain due to GON entrapment is thought to involve two possible pathophysiologies. One is the possibility that generalized pain is caused by sensitization of third-order nociceptive neurons in the thalamus. Another speculation is that spontaneous pain may occur throughout the body due to dysfunction of the descending brain stem pain-modulating pathway by sensitization and hyperexcitation of the MDH and trigeminal brainstem sensory nuclear complex (TBSNC).

Minimally Invasive Preganglionic C2 Root Section for Occipital Neuralgia: 2 Case Reports and Operative Video

BACKGROUND

Occipital neuralgia is a painful condition that is believed to occur from processes that affect the greater, lesser, or third occipital nerves. Diagnosis is often made with a combination of classical symptoms, tenderness over the occipital region, and response to occipital nerve blocks. Cervical computed tomography or MRI may be obtained in multiple positions to detect any impingement. Diagnosis can be made with MRI tractography. Nonsurgical treatments include local anesthetic and steroid injections, anticonvulsant medications, botulinum toxin injections, physical therapy, acupuncture, transcutaneous electrical stimulation, cryoneurolysis, and radiofrequency ablation. Surgical treatments include greater occipital nerve decompression, C2 root section, intradural dorsal root rhizotomy, C1-2 fusion, and occipital nerve stimulation. Although stimulation has been favored in the past decade, complications and maintenance of the devices have led us to return to C2 ganglionectomy.

OBJECTIVE

To report on the use of a minimally invasive technique for C2 ganglionectomy to treat occipital neuralgia.

METHODS

Review demographic, surgery, and outcome data of a minimally invasive C2 root ganglionectomy used to treat to 2 patients with occipital neuralgia.

RESULTS

We report on 2 patients with clinically stereotypical unilateral occipital neuralgia confirmed by greater occipital nerve block, but with no imaging correlate. Both were successfully managed by C2 ganglionectomy through an 18-mm tubular retractor and outpatient surgery. Accompanying text, still photographs, and video describe the technique in detail.

CONCLUSION

Minimally invasive C2 ganglionectomy can be used to successfully treat occipital neuralgia.

New and Advanced Magnetic Resonance Imaging Diagnostic Imaging Techniques in the Evaluation of Cranial Nerves and the Skull Base

The skull base and cranial nerves are technically challenging to evaluate using magnetic resonance (MR) imaging, owing to a combination of anatomic complexity and artifacts. However, improvements in hardware, software and sequence development seek to address these challenges. This section will discuss cranial nerve imaging, with particular attention to the techniques, applications and limitations of MR neurography, diffusion tensor imaging and tractography. Advanced MR imaging techniques for skull base pathology will also be discussed, including diffusion-weighted imaging, perfusion and permeability imaging, with a particular focus on practical applications.

Magnetic resonance neurography of the head and neck: state of the art, anatomy, pathology and future perspectives

Magnetic resonance neurography allows for the selective visualization of peripheral nerves and is increasingly being investigated. Whereas in the past, the imaging of the extracranial cranial and occipital nerve branches was inadequate, more and more techniques are now available that do allow nerve imaging. This basic review provides an overview of the literature with current state of the art, anatomical landmarks and future perspectives. Furthermore, we illustrate the possibilities of the three-dimensional CRAnial Nerve Imaging (3D CRANI) MR-sequence by means of a few case studies.

Diffusion tensor imaging of the C1-C3 dorsal root ganglia and greater occipital nerve for cervicogenic headache

Background

Previous studies showed neurography and tractography of the greater occipital nerve (GON). The purpose of this study was determining diffusion tensor imaging (DTI) parameters of bilateral GONs and dorsal root ganglia (DRG) in unilateral cervicogenic headache as well as the grading value of DTI for severe headache. The correlation between DTI parameters and clinical characteristics was evaluated.

Methods

The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values in bilateral GONs and cervical DRG (C2 and C3) were measured. Grading values for headache severity was calculated using a receiver operating characteristics curve. The correlation was analyzed with Pearson’s coefficient.

Results

The FA values of the symptomatic side of GON and cervical DRG (C2 and C3) were significantly lower than that of the asymptomatic side (all the P < 0.001), while the ADC values were significantly higher (P = 0.003, P < 0.001, and P = 0.003, respectively). The FA value of 0.205 in C2 DRG was considered the grading parameter for headache severity with sensitivity of 0.743 and specificity of 0.999 (P < 0.001). A negative correlation and a positive correlation between the FA and ADC value of the GON and headache index (HI; r = –0.420, P = 0.037 and r = 0.531, P = 0.006, respectively) was found.

Conclusions

DTI parameters in the symptomatic side of the C2 and C3 DRG and GON were significantly changed. The FA value of the C2 DRG can grade headache severity. DTI parameters of the GON significantly correlated with HI.

Visualization of the morphology and pathology of the peripheral branches of the cranial nerves using three-dimensional high-resolution high-contrast magnetic resonance neurography

PURPOSE

To assess the feasibility and advantages of high-resolution high-contrast magnetic resonance neurography (HRHC-MRN) for visualizing the morphology and pathology of the peripheral branches of cranial nerves.

MATERIALS

cMRN (3D SPACE STIR sequence) and HRHC-MRN (contrast enhanced 3D SPACE STIR sequence) were performed at 3 T MR unit on 16 volunteers and 12 patients with head and neck tumors. Quantitative measurements such as SNR, CNR and CR were calculated. Three readers evaluated the continuity of the 10 major peripheral branches of cranial nerves using a 5-score scale (scores 0-4). Interobserver variability was tested. Quantitative measurements and scores were compared between cMRN and HRHC-MRN. The imaging features of the nerve pathology were analyzed.

RESULTS

The CRs of nerve to bone marrow, nerve to muscle, and nerve to gland were significantly higher with HRHC-MRN than with cMRN (P = 0.014, P = 0.02, P <0.001, respectively). The scores of all nerve trunks were significantly higher with HRHC-MRN than with cMRN (all, P < 0.001). For all nerves on HRHC-MRN, the interobserver consistency was excellent across the three readers (all κ > 0.8). The scores of the inferior alveolar nerve, hypoglossal nerve, lingual nerve, facial nerve, infraorbital nerve, masseteric nerve, glossopharyngeal/vagus nerve, supraorbital nerve, auriculotemporal nerve and buccal nerve were 3.95, 3.77, 3.63, 3.25, 3.15, 3.04, 3.04, 2.87, 2.79, 1.88, respectively.

CONCLUSION

HRHC-MRN provides improved visualization of the peripheral branches of cranial nerves and is a promising nerve-selective imaging method for evaluating cranial nerve morphology and pathology.

Neurologic Disorders of the Maxillofacial Region

The maxillofacial region is complex in its anatomy and in its variation in the presentation of neurologic disorders. The diagnosis and management of neurologic disorders in clinical practice remains a challenge. A good understanding of the neurologic disorder in its entirety helps dentists in the diagnosis and appropriate referral to a specialist for further investigations and management of the condition. Neurologic disorders described in this article are under broad categories of sensory and motor disturbances as well as movement disorders and infections. This article summarizes the most common maxillofacial neurologic disorders that dentists might encounter in clinical practice.

DTI of great occipital nerve neuropathy: an initial study in patients with cervicogenic headache

AIM

To assess differences in bilateral great occipital nerves (GONs) in patients with unilateral cervicogenic headache (CEH) using diffusion tensor imaging (DTI).

MATERIALS AND METHODS

Twenty-three patients with unilateral CEH underwent GON magnetic resonance imaging (MRI). The clinical characteristics and fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) values in bilateral GONs were determined by two observers with 7 and 3 years of experience in MRI. Three segments of GON were defined based on anatomy. The correlation of DTI measurements to the clinical characteristics and inter-/intra-observer performance were also evaluated.

RESULTS

The mean GON FA for the symptomatic side was significantly lower (0.198±0.056) than that on the other side (0.311±0.04; p=0.000). The mean GON ADC for the symptomatic side was significantly higher (0.682±0.174) than that on the other side (0.465±0.138; p=0.000). Among the three defined segments of GON, statistically significant differences of ADC values were not found at segment S3 (0.692±0.257 versus 0.557±0.230; p=0.068). There were statistically significant differences of FA and ADC values in bilateral GON of segments S1 and S2. The intraclass correlation coefficient (ICC) of intra-/interobserver statistical analysis showed excellent inter/intra-observer agreement for FA and ADC. Significant correlation was only found between the duration and ADC.

CONCLUSION

In patients with unilateral CEH, quantitative evaluation of the GON using DTI demonstrated FA decreases and ADC increases of the symptomatic side. Larger population and other occipital nerve neuropathy can be included in future research.

Surgical Treatment of Migraine Headache: Back to the Future

Understanding the history and evolution of ideas is key to developing an understanding of complex phenomena and is the foundation for surgical innovation. This historical review on migraine surgery takes us back to the beginnings of interventional management for migraine centuries ago, and reflects on present practices to highlight how far we have come. From Al-Zahrawi and Ambroise Paré to Bahman Guyuron, two common themes of the past and present have emerged in the treatment of migraine headache. Extracranial treatment of both nerves and vessels is being performed and analyzed, with no consensus among current practitioners as to which structure is involved. Knowledge of past theories and new insights will help guide our efforts in the future. One thing is clear: Where we are going, there are no roads. At least not yet.