الفهرس 
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Abstract
Rheumatoid arthritis (RA) is a chronic and progressive systemic inflammatory disorder predominantly affecting synovial joints. It is characterized by a varied course, which ranges from spontaneously remitting symmetric synovitis to aggressive ankylosing, severely disabling joint disease. Clinical involvement of the PNS may present with a wide variety of symptoms like pain, paresthesias, and muscle weakness. These symptoms may mimic and overlap with those of arthritis. Peripheral neuropathies associated with RA can be classified into two broad categories; compressive (demyelinating) and vasculitic (axonal) neuropathies. This study aimed to evaluate the neuropathic foot and ankle pain in patients with RA using electrophysiological studies and musculoskeletal ultrasound. This research was carried out on fifty RA patients who have neuropathic pain in their ankles and/or feet. RA was diagnosed according the 2010 ACR/EULAR criteria for classification of RA. According to the cut-off point of the Disease Activity Score in 28 joints (DAS28), the patients were divided into 2 groups; group I (Active group) and group II (Remission group). Twenty-five apparently healthy subjects, having no pain and/or burning in their ankles and feet, were included as group III (Control group). characteristics of the studied groups were as follows; group I patients (active group) showed an evidence of disease activity. i.e., DAS28 was more than 2.6. It included 25 patients; 2 males (8%) and 23 females (92%), their ages ranged from 23 – 57 years, with a mean age of 42.40 ± 8.31 years. Disease duration ranged from 4 – 25 years with a mean duration of 10.36 ± 6.2 years. group II patients (remission group) showed an evidence of clinical remission. i.e., DAS28 was less than 2.6. This group included 25 patients; 2 males (8%) and 23 females (92%), their ages ranged from 28 – 52 years, with a mean age of 37.20 ± 6.80 years. Disease duration ranged from 2 – 15 years with a mean duration of 7.60 ± 4.34 years. Finally, group III (control group) included 25 patients; 5 males (20%) and 20 females (80%), their ages ranged from 23 – 59 years, with a mean age of 37.44 ±11.57 years. All subjects underwent a complete history taking, rheumatologic examination; general and local examination. Routine tibial and peroneal nerve conduction studies, as well as electromyography of tibialis anterior and abductor hallucis muscles were performed. Musculoskeletal ultrasound assessment of the the ankle joint and extra-articular portion of the foot complex was also performed. The study displayed the following results: - The females and males constituted 92% and 8% respectively in both of the patients groups, with predominance of disease in females - There was significant prevalence of muscle weakness among patients in group I when compared to group II patients. - There was significant prevalence of muscle wasting among group I patients when compared to group II patients. - Altered pinprick threshold, which is pathognomonic of neuropathic pain, was a prevalent finding among the patients, with no significant relationship between this deficit and disease activity. - There were significant prevalence of high Swindon Foot and Ankle Questionnaire (SFAQ) and high Stanford Health Assessment Questionnaire 8-item Disability Index (HAQ-DI) scores among patients in group I when compared to group II patients. - Nerve conduction studies (NCSs) revealed many changes in parameters of the motor and sensory nerve studies regarding mean values of distal latency, amplitude, and conduction velocity for RA patients compared to the healthy subjects. All the changes range from significant to highly significant, except for motor nerve conduction velocity (MNCV) of the deep peroneal nerve, distal sensory latency (DSL) of superficial peroneal nerve, sensory nerve action potentials (SNAP) amplitude of medial and lateral plantar nerves being not significant. Moreover, there were prevalent unobtainable sensory responses among the patients groups in comparison with the control persons. - Needle electromyography (EMG) of the studied muscles revealed the motor unit action potential (MUAP) showed significant to highly significant reduction in duration and amplitude among the patients in comparison with the control group. There were statistically insignificant higher proportions of polyphasic potentials in both muscles in patients compared with control group. In addition, 16% of the patients showed the neuropathic form, while none of the patients showed the myopathic form. - Comparison between groups I and II with respect to nerve study parameters was insignificant, except for the SNAP amplitude of the superficial peroneal nerve, being significant. In addition, bivariate correlation analyses between nerve study parameters and DAS28 showed insignificant results, except for DSL and SNAP amplitude of the medial plantar response, being significant in group II patients. - Out of 50 patients, 39 patients (78%) had different electrophysiological patterns of peripheral neuropathy. 24 patients (48%) had mononeuropathies of demyelinating pattern (entrapment neuropathies) and 15 patients (30%) had symmetrical polyneuropathy with axonal degeneration. - The commonest type of neuropathy observed was pure sensory axonal neuropathy that was found in 12 patients (24%) followed by posterior tibial nerve entrapment at the ankle that was shown in 10 patients (20%); followed by combined entrapments of posterior tibial nerve at the ankle and peroneal nerve at the fibular neck that was displayed in 8 patients (16%); followed by peroneal neuropathy at fibular neck that was found in 6 patients (12%), and finally distal sensorimotor axonal neuropathy that was shown in 4 patients (8%). - None of the studied cases showed deep peroneal neuropathy at the ankle, pure motor axonal neuropathy, or mononeuritis multiplex.
- Out 50 patients, 15 patients (30%) showed the electrophysiological findings of mild distal symmetric pure sensory and combined sensori-motor axonal neuropathies. Pure sensory neuropathy was displayed in 12 patients (24%) and combined sensori-motor neuropathy was shown in 3 patients (6%). These findings contribute to the clinical presentation of distal sensory neuropathy (DSN). - Posterior TTS was a relatively frequent finding in the patients as it was reported in 18 patients (36%); 10 patients (20%) showed an isolated posterior TTS and 8 patients (16%) showed an associated peroneal nerve entrapment at the fibular neck. - In cases diagnosed as posterior TTS, lateral plantar nerve affection was relatively more common than medial plantar affection. Of the 18 subjects diagnosed as posterior TTS, an isolated affection of lateral plantar nerve alone was encountered in 10 (20%) cases; affection of both medial and lateral plantar nerves together was observed in 8 (16%) cases with a total of 18 (36%) cases of posterior TTS. None of the studied cases showed isolated medial plantar nerve affection. - Peroneal nerve entrapment at fibular neck was reported in 14 subjects (28% of subjects); 6 cases had an isolated peroneal nerve affection, and 8 cases had an associated posterior tibial nerve entrapment at the ankle. - In cases diagnosed as peroneal nerve entrapment at the fibular neck, the peroneal entrapment affected both superficial and deep peroneal branches in 10 cases, while the rest showed an isolated affection of the deep peroneal branch. None of the cases showed an isolated superficial peroneal nerve lesion. - Semi-quantitative gray-scale ultrasound (GSUS) assessment for ankle synovitis and tenosynovitis was performed. Of the 25 patients of group I, 23 patients (92%) had GSUS synovitis; 2 patients (8%) were graded as zero, 9 patients (36%) were graded as one, 6 patients (24%) were graded as two and 8 patients (32%) were graded as three. Tenosynovitis was displayed in 21 patients (84%) in group I. Of the 25 patients of group II, 21 patients (84%) had GSUS synovitis; 4 patients (16%) were graded as zero, 11 patients (44%) were graded as one, 4 patients (16%) were graded as two and 6 patients (24%) were graded as three. Tenosynvoitis was displayed in 17 patients (68%) in group II. There was no statistically significant difference between both of the patients groups regarding ankle synovitis and tenosynovitis. - Power Doppler (PD) activity was evaluated using a semi-quantitative scoring system. Of the 25 patients of group I, 100% of the patients had positive PD findings; 9 patients (36%) were graded as one, 6 patients (24%) were graded as two and 10 patients (40%) were graded as three. Of the 25 patients of group II; 23 patients (92%) were graded as zero (no PD signal), 2 patients (8%) were graded as one, and none of patients were graded as two or three. There was a highly statistically significant prevalence of positive ankle PD signals among group I patients in comparison with group II patients, which indicates that Doppler imaging reflects disease activity. - On assessing joint erosions, there was a highly statistically significant prevalence of erosions in group I when compared to group II. Joint erosions were recorded in 23 patients (92%) in group I; while they were only present in 5 patients (20%) in group II. - Ultrasound diagnosis of posterior TTS was encountered in 6 patients (24%) of group I and 2 patients (8%) of group II. There was no statistical prevalence of the condition in group over another. - US evaluation of the plantar fascia revealed findings consistent with bilateral plantar fasciitis in 4 patients (16%) of group I, and in 2 patients (8%) of group II, with no statistical difference between groups regarding the condition. - Comparison between the electrophysiological and the US diagnoses of posterior TTS revealed statistically significant results; in which electrophysiology could detect the syndrome in 18 patients (36%), while MSUS could detect only 8 patients (16%).