Combined Phrenic Nerve Palsy and Cervical Facet Joint Pain
Diabetes mellitus (DM) is a common metabolic disorder and is associated with multiple systems and organ dysfunction including the central nervous system (CNS) and peripheral nervous system (PNS). The involvement of the PNS includes various forms of DM neuropathies. It is well documented that DM can cause restrictive lung dysfunction.1 The diaphragm seems to be affected more than other inspiratory muscles, perhaps due to its length/size.1
Phrenic nerve palsy (PNP) has been reported following trauma. Nontraumatic causes of PNP include some metabolic disorders including DM. This could be as a part of systemic diabetic poly-neuropathies or, uncommonly, as a solo mono-neuropathy.1,2 Here we report a case of PNP following a motor vehicle accident (MVA). This also was associated with cervical facet injury and created pain management challenges which will be discussed.
History, Examination and Diagnosis. A 44-year-old male was referred to the pain clinic for two different types of complaints.The first complaint was for a long standing neck pain of 14 months following a motor vehicle accident. This involved the right more than left side and increased by neck movement, especially with rotation. The neck pain did respond minimally to chiropractic mobilization and NSAIDS.
The second complaint was for sudden onset of dyspnea when the patient was lying flat. This was so uncomfortable that he was forced to sleep in a recliner. Due to the dyspnea, he had poor night sleep, daytime somnolence, and headache. He was averaging 2-4 hours of sleep at night. The shortness of breath was initially with exertion and was only apparent in the last two months (more than 12 months following the MVA).
The Review of Systems was negative except for Type I diabetes mellitus (NIDDM) controlled by an oral hypoglycemic agent (glucophage). The physical examination revealed a well-developed male, with an examination of the chest that was clear on auscultation with good air entry to both lungs. Heart sounds were normal; no gallop or added sounds/murmurs. However the patient was slightly short of breath when asked to lie flat in bed. Both the cranial nerve and neurological examinations were also normal. The musculoskeletal examination showed tenderness over the C3/4 and C4/5 facet — left more than the right — with reduced range of motion especially with extension and rotation to the right side. This was consistent with cervical facet dysfunction. The rest of the neurological examination was within normal limits.
Respiratory function tests showed a mild restrictive pattern. The flow-volume curve also had a mild restrictive pulmonary pattern. This did not improve with pretreatment utilizing bronchodilators. Chest x-ray revealed an elevated right diaphragm with possible PNP. This was confirmed by fluoroscopic sniff test. The Sniff Test revealed paradoxical movement of the diaphragm.
Our diagnosis was C3/4 and C4/5 facet dysfunction/pain due to the MVA and PNP due to DM.
Treatment. Since our patient was a middle-aged nonsmoker with a normal baseline pulmonary function, we elected to proceed with conservative therapies. These included respiratory therapy/rehabilitation and proper sleeping position (lateral, semi-recumbent with affected side up) and reassurance.
For medical and legal reasons, we did C3/4 and C4/5 facet joint injections on the right side with lidocaine and steroid under fluoroscopic guidance. Only 0.5ml of 2% lidocaine was used to avoid extra-articular spill and reduce adverse events from somatic nerve spread (see discussion). This produced excellent analgesia. To avoid bilateral PNP, we also did left side facet C3/4 and C4/5 injections a week later with similar pain relief.
In our case, pulmonary function tests showed only mild restrictive dysfunction. We elected to treat that conservatively with reassurance, sleeping in a lateral semi-recumbent position, with the affected side up. This improved the sleep pattern so no hypnotics were used. The pulmonary consultant was in agreement with the plan. A more than 4 month follow up showed excellent pain relief following the facet block. The sleep pattern was better and the headache almost resolved. However, a repeat of the Sniff Test did not show any improvement in the phrenic nerve/diaphragm function on the right side.
“At the nine month follow up visit, the patient had minimal cervical pain, and his range of motion had significantly improved. His chest pain and dyspnea improved with reassurance, proper positioning during sleep and respiratory physical therapy.”
At the nine month follow up visit, the patient had minimal cervical pain, and his range of motion had significantly improved. His chest pain and dyspnea improved with reassurance, proper positioning during sleep, and respiratory physical therapy. However, there were no signs of phrenic nerve recovery on chest X-Ray films.
Diabetes mellitus (DM) is a common metabolic disorder that affects almost all organs/systems. Diabetes mellitus mono-neuropathy is a common and usually reversible type of DM neuropathy.1-3
Involvement of the phrenic nerve as part of DM mononeuropathy is a rare complication and a somewhat controversial entity.1-5 Wank et al. showed normal phrenic latency in Type I DM with restrictive lung disorders. The authors concluded that diaphragmatic weakness in DM and the restrictive pattern of pulmonary function tests could not be explained only on the grounds of PNP. However there were 14 cases reported. In another study, 23% of DM patients had prolonged phrenic nerve latencies and respiratory complaints.1,2
There are only a few well-documented cases of phrenic nerve palsy due to DM. Some were confirmed by autopsy results and electromyography (EMG) studies which were consistent with DM neuropathy.2,3 There is no correlation between duration and type of DM and newly-diagnosed PNP.
PNP can be associated with other metabolic, congenital, inflammatory (Guillain-Barré syndrome) and central nervous system disorders (multiple sclerosis, amyotrophies). Other causes of PNP which should be considered are forceful neck manipulation and cervical spine traumas.2-4 Phrenic nerve is more susceptible to trauma probably because of the length of the nerve.1 In our case, we could not find another causative factor. The history of MVA was more than one year — far remote to explain the sudden onset. While manipulation can result in PNP, this was not the case here (no physical therapy or manipulation for the previous three months). There was no other metabolic or inflammatory condition to explain the PNP apart from Type I DM.
In most cases of DM neuropathy (DMN), the correlation between the glycemic control and the severity of the sensory and autonomic dysfunction is well defined. However, that may not be the case for predominantly motor neuropathies.2 The picture of pure motor neuropathy is usually more of acute onset and typically accompanied with pain (dyspnea and chest pain), as in our case.2,3