gms | German Medical Science

Objective: Precise positioning of the electrodes remains imperative when performing spinal cord stimulation in order to achieve a satisfying long term outcome. Dislocations of the electrodes due to the patient's movement have to be avoided at all costs. The Penta^TM lead (St. Jude Medical) is new and currently the smallest electrode in order to achieve precise field control and broad lateral coverage. It was designed to enable selective nerve fibre stimulation and a predictable dermatomal activation. We examined this electrode prospectively.

Methods: The patients in our study had neuropathic pain (n = 8, 5 male, 3 female, age range 37–79 years, mean age 58 years, failed back surgery syndrome n = 5, cluster headache n = 1, persistent post-herniorrhaphy pain n = 1, CRPS 1 n = 1, postherpetic neuralgia n = 1). They were operated on using a flavectomy under general anaesthesia. The lead was positioned epidurally in the spinal canal. We examined the pain intensity by using the Visusal Analogue Scale (VAS), quality of life (QoL), SF 36 Scale, Brief Pain Inventory, Pain Disability Index and the drug consumption. The evaluations were conducted preoperatively on admission and three months later.

Results: The leads were located at the cervical level C1 (n = 1), C3 (n = 1), and at the thoracic level D8 (n = 5), D10 (n = 1). In 2 of the patients (persistent post-herniorrhaphy pain, CRPS 1) the postoperative test trial was unsuccessful and the lead had to be removed. Six patients received a permanent pulse generator. After 3 months, the VAS was remarkably decreased by > 50% in 5 of the patients and by 30% in one patient (p < 0,001). Three of the patients were able to discontinue their pain medication. No dislocation has occurred so far.

Conclusions: The Penta^TM lead can be safely placed using a flavectomy. The broad lateral extension of the electrode compensates anatomical asymmetries as well as placement variations. The five column array also provides more flexibility in order to create a specific dermatomal activation. However, a general anaesthetic is necessary in order to place the electrode. An intraoperative test-trial cannot be carried out. Because of this, the Penta^TM lead should therefore ideally be used in patients with dislocations after previous singular lead implantations where the location of the best stimulation result is already known.