Occipital Neuralgia: a noninvasive therapeutic approach

ABSTRACT Objective: to evaluate the application of a noninvasive intervention consisting of a postural modification using personalized models and osteopathy in people with occipital neuralgia. Method: retrospective study of the intervention performed in adult population with occipital neuralgia, consisting of postural modification using personalized plantar orthoses and osteopathy, in a study period of four years. The observed variables were: persistence of headache, alignment of the axes, plantar support, center of gravity and center of mass; medical interview data, visual analogue scale, Win-Track gait analysis system and Kinovea software for video analysis (clinical assessment instruments used). Results: a total of 34 records of people with occipital neuralgia were studied. A fraction of 58.8% of the patients reported improvement after the intervention. The visual analogue scale data were provided for 64.7% of the records and significant differences (p <0.001) between the means before (8.4 ± 1.7) and after the intervention (2.6 ± 2.7) were found. Conclusion: postural modification using personalized orthoses and osteopathy substantially improves the symptomatology of patients with occipital neuralgia.


Introduction
Neuralgia is considered the most frequent neuropathy. It was described by Beruto and Lentijo and Ramos in 1821, being defined as a disabling alteration characterized by recurrent headaches located in the occipital region (1) . According to the classification by the International Headache Society (IHS), occipital neuralgia (ON) is defined as "unilateral or bilateral paroxysmal pain, of lancinating or acute nature that is located in the posterior part of the scalp in the distribution of the major, minor and third occipital nerves, which on certain occasions is accompanied by reduced sensitivity or dysesthesia in the affected area and is usually associated to hypersensitivity of the affected nerve or nerves" (2) . This type of neuralgia is classified into a subset that includes post-traumatic pain, lash, cervical spine deformity, tension headache, chronic daily headache and migraine (3)(4) . In addition to occipital neuralgia, the scientific community employs other terms for its definition, such as C2 neuralgia, Arnold neuralgia, or occipital neuritis (5)(6) . Other characteristics are the presence of pain that recovers the ocipucius that diminishes after the use of anesthetic blocks of the affected nerves (2,4) .
ON is a multiple-cause clinical condition. In its manifestation, several factors (7) may be involved: The therapeutic approach is very broad. Regarding treatment, the conservative methods were: use of antiepileptics, antidepressants, nervous block, nonsteroidal analgesics, opioids, neuromodulators, and transcutaneous electrical nerve stimulation, as well as cervical orthoses. However, the scientific community also approves the use of surgery as the last therapeutic option: neurolysis and decompression, neurectomy, rhizotomy and ganglionectomy, C1-C2 fusion, radiofrequency ablation, and peripheral nerve stimulation (7) . Nevertheless, the use of different therapeutic options does not always result in the remission of the symptomatology, together with the fact that they are painful. Therefore, it is considered necessary to propose therapeutic alternatives that lead to more effective therapeutic results.
The starting hypothesis of the present study was the fact that the appearance of the symptoms associated with occipital neuralgia was of biomechanical origin, considering the cause of the occipital neuralgia a postural alteration that has as consequence the nervous/venous compression of the root of the C2 vertebra (8) . In this sense, we describe the results that efficacy of the intervention: ergodynamic gait study, posturology study and lower limb dysmetria; as well as post-intervention pain level.
As indicated, in addition to the medical interview for data collection, VAS was used to determine pain level, and baropodographies (N/cm 2 ) were used to determine the different pressures exerted by the foot, using the NOVEL-EMED-Model AT ® device. As a gait analysis system, the Win-Track device (Medicapteurs, France-USA) (9) was used.   After the three follow-up visits, a large percentage of patients (N=13; 38.2%) reported no persistence of occipital neuralgia; 20.6% reported improvement and neuralgia was less persistent. However, five patients (14.7%) indicated that the symptomatology persisted and from 23.5% data was not obtained. Concerning VAS, only 64.7% (N=22) provided information on the records, with significant differences (p <0.001) between means previous (2.6 ± 2.7) and after (8.4 ± 1.7) the intervention.
At the end of the study period, 20 of the 34 subjects studied (58.8%) remained with plantar orthoses and four of them did not use them (11.7%); of the other subjects, no data was obtained. On the other hand, 35.2% of the patients did not take any medication at the end of the study; 11.7% only took it when they had a crisis and 14.7% took antiinflammatory drugs; regarding the other subjects studied, there is no data available.
Regarding the posturology study (N = 9), including the plantar orthosis, all the subjects presented improvement in the alignment of the axis, as well as the distance to said axis, according to  The most common therapeutic measure is the infiltration of local anesthetic agents with and without steroids, a technique that alleviates pain in some cases (15% -36%) (10)(11)(12) . In this sense, a high percentage of patients (58.8%) experienced pain reduction after orthoses implantation. In addition to infiltration with or without steroids, botulinum toxin A was used for its inhibitory effect on the motor plaque as a muscle relaxant, although its possible analgesic action was indirect (13)(14) , reducing only the associated acute and pungent ON pain, not constant and only pain for several months (15) . The postural correction intervention showed continuous improvement in the three follow-up visits, a fact that strengthens the application of these measures in future studies.
On the other hand, some studies show the efficacy of pulsed radiofrequency in the treatment of ON.
Nevertheless, the known studies are observational without controls and in the same way as in the previous case, only short and medium-term pain control is observed (16)(17)(18) .
Surgical techniques are also used for the treatment of ON, such as occipital neurolysis and stimulation of the occipital nerve. However, it has been documented that the use of these techniques increases the possibilities of developing entities of worse therapeutic control than neuralgia, for example, neuroma or regional pain syndrome (19) .
However, the present study has several limitations.
Despite the fact that there were statistically significant differences after postural correction in ON symptomatology, the retrospective nature and consequently, follow-up losses, does not allow to determine exclusively the effectiveness of the treatment, due to the fact that there are no control groups. Moreover, the VAS scale determines the perception of pain, nevertheless, the control of neuropathic pain requires evaluation of the psychological aspects (20) , a fact that is not usually considered in interventional studies in this neuralgia.

Conclusion
The application of customized orthoses, and in some cases osteopathy, substantially improves the postural alignment (acromion-clavicular, trochanter and external malleolus) and as a consequence, the symptomatology of ON. It is possible to conclude that after the noninvasive intervention, the level of neuropathic pain decreased significantly.
This therapeutic alternative, according to our knowledge, was not approached by the scientific community and could be considered as a first approach in the treatment of ON. On the other hand, clinicians should consider that invasive and/or surgical techniques may trigger less controllable clinical conditions than the underlying entity. In this sense, a consensus is needed in the scientific community to establish an adequate therapeutic algorithm.
Despite the interesting results of our study, the data obtained should be considered with caution due to its limitations. Future prospective studies should be conducted that include control groups and evaluation of psychological variables that may influence the perception of pain.