Cervico-occipital pain and its surgical treatment: the myth of the bony millstones

Occipital neuralgia: A neurosurgical perspective

Occipital neuralgia typically arises in the setting of nerve compression by fibrosis, surrounding anatomic structures, or osseous pathology, such as bone spurs or hypertrophic atlanto-epistropic ligament. It generally presents as paroxysmal bouts of sharp pain in the sensory distribution of the first three occipital nerves. Due to the long course of the greater occipital nerve (GON), and its peculiar anatomy, and location in a mobile region of the neck, it is unsurprising that the GON is at high risk for compression. Little is known how to diagnose or treat this neuropathic pain syndrome. The objective of this paper is to isolate the etiology involved, and treat this condition promptly. After all nonoperative efforts are exhausted, surgical transection of the nerve is the treatment of choice in these cases. An isolated C2 neurectomy or ganglionectomy is performed for an optimal pain relief. C1-2 instrumented fusion can be considered if, extensive facet arthropathy with instability is identified. Authors review the spectrum of treatment options for this debilitating condition, and discuss the case example of a patient who required conversion to a C1-C2 instrumented fusion following C2 ganglionectomy due to an underlying extensive degenerative disease and intraoperative findings suggestive of atlantoaxial instability.

Role of anesthesiologic blockade in headache management

Local anesthetic blocks have been used in a variety of ways in the management of headache. Some practitioners use blocks of the supraorbital and greater occipital nerves as a form of treatment. Although the effect of each block is limited in duration, a series of injections appears to provide sustained relief. However, no controlled studies have vindicated blocks as a tenable intervention. On the other hand, blocks can be used to diagnose cervical sources of headaches. When performed under controlled conditions, such blocks can identify cervical sources of pain in a substantial proportion of patients with headache after whiplash. Positive blocks also predict good outcome from radiofrequency neurotomy of the nerve blocked.

An anatomic and morphometric study of C2 nerve root ganglion and its corresponding foramen

STUDY DESIGN

Exposing and measuring the dorsal root ganglion of the second cervical spinal nerve (C2 ganglion) and the second intervertebral space, which is present between posterior arch of atlas (APA) and lamina of axis (LA).

OBJECTIVES

This study aims to investigate the shape, size, and relation of the C2 ganglion with the adjacent structures that limits the corresponding intervertebral space and the alterations of relation between C2 ganglion and APA and between C2 ganglion and LA with the movements of the head bilaterally.

SUMMARY OF BACKGROUND DATA

In previous studies, the position and the heights of the C2 ganglion have been described. But the shape of the C2 ganglion and its relation to APA and LA by the movement of the head had not been considered previously.

METHODS

Upper cervical spines of 20 cadavers were dissected posteriorly. The muscles attaching to the atlas and axis were resected to ease the head movements. The heights of the C2 ganglion and space were measured in anatomic position and in hyperextension with opposite rotation position of the head. Originally in this study, plastic dough casts were used to obtain reliable outcomes.

RESULTS

The shape of the ganglions was defined in three types: 70% were oval, 20% were spindle-like, and 10% were spherical. The height of the C2 ganglion was 4.97 +/- 0.92 mm on the right side and 4.6 +/- 0.84 mm on the left side. The height of the intervertebral space in anatomic position and in hyperextension with rotation to the opposite position of the head were, respectively, 9.74 +/- 1.77 mm and 7.48 +/- 1.44 mm on the right side and 9.64 +/- 1.47 mm and 7.12 +/- 0.96 mm on the left side. There was no bone contact or impact to the ganglion in each position of the head.

CONCLUSION

The C2 ganglions are confident in their place between APA and LA. No bone contact to the C2 ganglion was detected in either normal limited or in forced head motions.

The neck and headaches

Referred pain from disorders of the cervical spine can be perceived as headache. The mechanism is convergence between trigeminal afferents and afferents of the upper three cervical nerves in the trigeminocervical nucleus. Cervicogenic headache cannot be diagnosed on clinical grounds alone. The definitive criterion is complete relief of pain after controlled diagnostic blocks of cervical structures or their nerve supply. The most rigorously studied example of cervicogenic headache is third occipital headache.

Whiplash syndrome: kinematic factors influencing pain patterns

STUDY DESIGN

The overall, local, and segmental kinematic responses of intact human cadaver head-neck complexes undergoing an inertia-type rear-end impact were quantified. High-speed, high-resolution digital video data of individual facet joint motions during the event were statistically evaluated.

OBJECTIVES

To deduce the potential for various vertebral column components to be exposed to adverse strains that could result in their participation as pain generators, and to evaluate the abnormal motions that occur during this traumatic event.

SUMMARY OF BACKGROUND DATA

The vertebral column is known to incur a nonphysiologic curvature during the application of an inertial-type rear-end impact. No previous studies, however, have quantified the local component motions (facet joint compression and sliding) that occur as a result of rear-impact loading.

METHODS

Intact human cadaver head-neck complexes underwent inertia-type rear-end impact with predominant moments in the sagittal plane. High-resolution digital video was used to track the motions of individual facet joints during the event. Localized angular motion changes at each vertebral segment were analyzed to quantify the abnormal curvature changes. Facet joint motions were analyzed statistically to obtain differences between anterior and posterior strains.

RESULTS

The spine initially assumed an S-curve, with the upper spinal levels in flexion and the lower spinal levels in extension. The upper C-spine flexion occurred early in the event (approximately 60 ms) during the time the head maintained its static inertia. The lower cervical spine facet joints demonstrated statistically greater compressive motions in the dorsal aspect than in the ventral aspect, whereas the sliding anteroposterior motions were the same.

CONCLUSIONS

The nonphysiologic kinematic responses during a whiplash impact may induce stresses in certain upper cervical neural structures or lower facet joints, resulting in possible compromise sufficient to elicit either neuropathic or nociceptive pain. These dynamic alterations of the upper level (occiput to C2) could impart potentially adverse forces to related neural structures, with subsequent development of a neuropathic pain process. The pinching of the lower facet joints may lead to potential for local tissue injury and nociceptive pain.

Anatomic considerations of C2 nerve root ganglion

STUDY DESIGN

Dissection and observation of the dorsal root ganglion of the second cervical spinal nerve bilaterally.

OBJECTIVES

To determine the position of the C2 dorsal root ganglion and the heights of the C2 ganglion and its corresponding foramen.

SUMMARY OF BACKGROUND DATA

The dorsal root ganglion has been well studied in the middle and lower cervical spine and in the lumbar spine. In no previous study are the position and height of the C2 dorsal root ganglion and its corresponding foramen described.

METHODS

Fifteen cadaveric cervical spines were exposed posteriorly. The C2 nerve roots and ganglia were dissected between the arch of the atlas and the lamina of the axis. The heights of the C2 ganglion and foramen were measured. The location of the C2 ganglion was also macroscopically observed.

RESULTS

The heights of the C2 ganglion and foramen are 5.7 +/- 0.8 mm and 7.7 +/- 1.2 mm, respectively. The C2 ganglion occupies 76% of the foramen height. All C2 dorsal root ganglia are confined within foramens between the arch of the atlas and the lamina of the axis.

CONCLUSIONS

The C2 dorsal dorsal root ganglia are all proximally placed and occupy most of the foramen height, which may render the C2 ganglion vulnerable to entrapment.

Cervicogenic headache: anesthetic blockades of cervical nerves (C2-C5) and facet joint (C2/C3)

In a series of 14 patients with cervicogenic headache, cervical nerve blockades (C2-C5 and facet joint C2/C3) have been carried out in order to elucidate possible underlying mechanisms and to evaluate the diagnostic potential of these procedures. Blockade of the C2 nerve resulted in freedom from pain in 5 of 10 patients and seemed to be the most informative procedure. Two patients out of 9 reported freedom from pain following C2/C3 facet joint injection. No patients experienced complete pain relief following C3, C4 or C5 blockades. C4 and C5 nerve blockades are probably of little value in the work-up of such patients. When evaluating the C2/C3 facet joint injection, one has to take possible leakage of anesthetic agent from the joint into consideration, since the third occipital nerve which runs close to the facet joint may be anesthetized through the leakage.

"Whiplash"-injury of the 2nd cervical ganglion and nerve

Amongst the many patients with persisting neck pain and headache following cervical injuries are a small number in whom the mechanism is compression of the second cervical nerve root and ganglion. This paper describes the clinical features in 14 patients seen by the author. The main features are unilateral pain in the upper cervical and occipital region, tenderness in the suboccipital region, and diminished sensation in the C2 dermatome. The anatomical basis for this syndrome is discussed and illustrated with dissections from a cadaver.