Research news and notes

1. Facet arthropathy is a source of radicular pain 

The presence of a radiculopathy, especially pain, commonly leads to a search for a herniated disc. However, discs are not the only structure in contact with spinal nerves that can contribute to radiculopathy. In a study published earlier this year, Igarashi et al [3] demonstrate how inflammatory cytokines from the facet joint can cause symptoms of radiculopathy. The study had 2 components. In the clinical part, the authors collected tissue from surgical specimens of lumbar facet joint cartilage and synovial tissues in 40 patients who had posterior lumbar surgery. They measured tumor necrotizing factor-α, interleukin-1β, and interleukin-6 in the specimens. The visual analogue scale and Roland-Morris disability questionnaire were used to examine the correlation between cytokine concentration and symptoms. In surgery for spinal stenosis the cytokine levels were higher than in operations for herniated nucleus pulposus. Cases where interleukin-1β was elevated in the lumbar stenosis surgery group showed higher scores on both clinical parameters. In a separate experiment, the authors demonstrated that a pigment injected into the facet joints of cadavers leaked into the spinal canal through the lateral part of the ventral facet joint capsule. This leak provides a possible pathway for the cytokines from the inflamed and degenerated joint to reach the thecal sac and the spinal nerves.

The article raises the awareness of the variety of factors that can precipitate symptoms of radiculopathy and back pain. We should not focus on disc disease to the exclusion of other pathology. Facet arthropathy has been implicated in up to 15% of cases of low back pain [2]. It has not been frequently associated with radiculopathy, but that may change. A recent study in a rat model by Tachihara et al [7] demonstrated inflammatory reaction in the nerve root and epidural space after induction of facet joint inflammation. The outcome is expected—the inflammation does not have a large distance to spread. It is possible that facet arthropathy is an underdiagnosed cause of lumbar radiculopathy.

2. Endovascular therapy for aneurysms—beyond coils 

Coiling of aneurysms is an amazing invention—it has changed neurosurgery already and helped establish a whole new field of endovascular treatments, but is it the ideal therapy? Will it still be the method of choice in 10 or 20 years? Coiling has become very sophisticated, yet still limited by the anatomy and size of the aneurysm. New types of devices are needed to treat most aneurysms with endovascular approaches. In the August issue of Stroke, Kallmes et al [4] present a new stent-like device that is designed to disrupt the flow at the neck of an aneurysm. They tried it in 17 rabbits with elastase-induced aneurysms. The animals were followed for 1, 3, or 6 months. In half of them, complete occlusion of the aneurysms was seen and near complete occlusion in most of the others. The authors reported only minimal parent vessel compromise by neointimal hyperplasia in most cases. This experiment is an interesting demonstration of the potential of flow-altering devices. I speculate that flow-altering devices may have a more durable long-term outcome than coils. The latter may not change the flow dynamics at the neck of the aneurysm, leading to coil compaction, but a device that disrupts the flow at the neck can potentially prevent aneurysm regrowth in the long run.

3. Deep brain stimulation for Gilles de la Tourette syndrome 

Gilles de la Tourette syndrome (GTS) is a common disorder characterized by behavioral and verbal tics. It has close ties with obsessive compulsive and attention deficits—hyperactivity disorder [5]. Although it usually improves by the time patients reach adulthood and can be treated with medication, some patients remain disabled by their problem. For those, surgical options become attractive. Servello et al [6] from Milan recently tried deep brain stimulation (DBS) in 18 patients with GTS refractory to therapy. The electrodes were placed bilaterally in centromedian parafascicular and ventralis oralis complex of the thalamus. The patients were evaluated at least every 3 months and followed for 3 to 18 months. The authors performed on-off and sham-off assessments. Symptoms of the disease such as tics, as well as symptoms of obsessive-compulsive behavior, obsessive-compulsive disorder, self-injurious behaviors, anxiety, and premonitory sensations, decreased after treatment with DBS. An excellent result was also reported by Bajwa et al [1] from Yale who treated a 48-year-old man with severe GTS. The authors performed bilateral stimulation at the level of centromedian nucleus, the substantia periventricularis, and the nucleus ventro-oralis internus, with marked reduction of tics. These data demonstrate that DBS of medial thalamus can be beneficial for patients with severe GTS. Larger, sham stimulation–controlled studies are now in order.

This is another example of the expanding use of DBS for a variety of neurologic disorders. I suspect that we are nowhere near full utilization of the potential of DBS to treat chronic neurologic disorders.