Case series on variable presentation of ligamentum flavum stimulation following percutaneous cylindrical spinal cord stimulator lead implants.

BACKGROUND: Stimulation-evoked discomfort secondary to ligamentum flavum stimulation (LFS) is a technological limitation of percutaneous spinal cord stimulator (SCS) lead implants. There is a paucity of literature describing the clinical presentation and time periods at which this side effect may present following insertion of cylindrical lead(s). OBJECTIVE: To describe a series of 5 patients who presented at varying time periods after SCS lead placement with LFS. STUDY DESIGN: Retrospective case series. METHODS: We performed a chart review of online medical records of patients with symptoms consistent with LFS at an academic interventional pain clinic identified over 7 consecutive years (2006 - 2013). RESULTS: LFS most frequently presented within months of implantation of cylindrical leads. One patient complained of LFS during the temporary trial while another developed LFS after lead revision. All patients were successfully treated when paddle electrodes replaced percutaneous cylindrical leads. CONCLUSION: LFS may present as a barrier to successful SCS treatment. Clinicians placing percutaneous SCS leads should be aware of the variable time course of LFS presentation. Paddle style electrodes seem to offer an enduring solution to LFS so that patients may continue to benefit from SCS therapy.

Bcl-x is required for proper development of the mouse substantia nigra.

Recent findings have uncovered a role for the Bcl-x gene in the survival of dopaminergic neurons. The exact nature of this role has been difficult to examine because of the embryonic lethality of Bcl-x gene disruption in mouse models. Here we report the generation catecholaminergic cell-specific conditional Bcl-x gene knock-out mice using Cre-lox recombination technology. First we produced transgenic mice that express Cre recombinase from an exogenous rat tyrosine hydroxylase promoter (TH-Cre mice). These mice were crossed to Z/AP and Z/EG reporter mouse strains to verify catecholaminergic (TH-positive) cell-specific Cre expression. The TH-Cre mice then were mated to mice possessing the Bcl-x gene flanked by loxP sites, thereby producing offspring with Bcl-x deletion limited to catecholaminergic cells. The resulting mice are viable but have one-third fewer catecholaminergic neurons than do control animals. They demonstrate a deficiency in striatal dopamine and also tend to be smaller and have decreased brain mass when compared with controls. Surprisingly, surviving neurons were found that lacked Bcl-x immunoreactivity, thereby demonstrating that this gene is dispensable for the ongoing survival of a subpopulation of catecholaminergic cells.