Extradural cortical stimulation for central pain.

Central pain results from a central nervous system injury and represents a challenge for the pain therapist. Human studies have shown that motor cortex stimulation (MCS), i.e. the placement of a stimulating plate on the dura overlying the motor cortex can relieve brain central pain. Studies suggest that MCS directly affects activity in the first and second order somatosensory areas, thalamic nuclei and also inhibits spinal primary afferents and spinothalamic tract neurons. The following factors have been found to predict analgesia by MCS: intact or almost intact corticospinal motor function, mild or negligible sensory loss, absence of thermal sensory threshold alteration within the painful area, positive response to the barbiturate and/or ketamine test, positive response to the propofol test, positive response to transcranial magnetic stimulation (TMS). The targeting of the cortical area is made by anatomical localization by computed tomography (CT), magnetic resonance imaging (MRI), neuronavigation, intraoperative neurophysiological recordings, functional MRI (fMRI), and intraoperative clinical assessment. We perform the procedure under local anaesthesia. We describe in detail our surgical technique and stimulation protocol. Furthermore, we review the most important studies with respect to their results, the observed side effects and complications. The future prospects and likely developments of MCS for central pain are also discussed.

Low-rate repetitive TMS allays central pain.

Only about 50% of central pain patients respond to motor cortex stimulation in the long run. There is a need for prognostic factors. Here we show that propofol test and TMS both predict short-term effect in nine patients with central pain. This may help reduce the number of failures.

The important role of pain in neurorehabilitation. The neurosurgeon's approach or (neurorehabilitation: the neurosurgeon's role with special emphasis on pain and spasticity).

Pain syndromes due to peripheral or central nervous system damage, or both, may hinder neurorehabilitation. Control of pain may be obtained by ablative or augmentative procedures. Of the ablative modes only DREZ and Cordectomy are still being employed in cases of pain due to Brachial Plexus Avulsion and conus and cauda damage at T9-L1: in both pain is not simply due to "deafferentiation". The augmentative procedures include spinal cord, deep brain and cortical stimulation. Subarachnoid infusion of drugs (midazolam, clonidine, baclofen, etc.) is a new avenue open to control pain. Indications, results and mechanisms of action of those procedures in neuropathic pain are discussed on the basis of literature and personal experience.

Disappearance of central pain following iatrogenic stroke.

An exceptional case of long-standing central pain temporarily relieved by a focal stroke in the primary somatosensory area is reported. This case highlights the focal nature of central pain mechanisms and the possible value of selective subparietal leukotomies in the management of central pain.

Peri- and postoperative pain valutation in carpal tunnel release of median nerve compression.

We analysed 108 patients, operated on day surgery, for carpal tunnel release of median nerve compression, to evaluate peri- and postoperative pain. We made in all cases a short intertenarian incision (25 mm) with microsurgical technique and local anaesthesia using mepivacaine 2% without vasoconstrictor. We evaluated pain for local anaesthetic infiltration as VRS (Verbal Rating Scale) 6,3 median-time to the first possible analgesic assumption (in all cases paracetamol 500 mg), total analgesic assumption, pressure algometry (to evaluate "allodiny") after the first 48 hours and subjective pain intensity by a numerical pain scale. Pain intensity on first drug assumption (after a mean time of 7 hours from the end of surgery) had a mean VAS value of 2,15; while after a second assumption of analgesic (after a mean time of 15 hours from surgery) had a mean VAS value of 2. Mean total analgesic assumption was 1,64 tablets of paracetamol 500 mg. From these data we may deduce that peri- and postoperative pain following median nerve decompression with this technique and anaesthesia, has a moderate intense peak of brief duration, for local anaesthetic infiltration (that seems to be the most painful event) and modest and not constant pain in the postoperative time (more evident 7 and 15 hours from the end of surgery). It may be useful association with mepivacaine bicarbonate solutions or injecting less painful local anaesthetic.

Painful supernumerary phantom arm following motor cortex stimulation for central poststroke pain. Case report.

In this report, the authors describe a case in which the patient began to experience a supernumerary phantom arm after she received motor cortex stimulation for central pain. The patient had a history of right thalamocapsular stroke. It is speculated that the motor cortex activation triggered a response in the patient's parietal lobe, precipitating perception of the phantom limb. To the authors' knowledge this is the first reported case of its kind.

The neurochemistry of central pain: evidence from clinical studies, hypothesis and therapeutic implications.

Recent evidence suggests that central pain, i.e., pain due to central nervous system damage, may be due to a deranged neurotransmission between the sensory thalamus and sensory cortical areas. Central pain can be controlled either by opposing glutamate neurotransmission or potentiating GABAergic transmission. It is speculated that a relative hypofunction of the GABAergic inhibition both at thalamic and cortical levels leads to a sectorial excitatory hypertonus in those same areas. A blend of the two should mark each patient. A pharmacological dissection approach is provided that should optimize the treatment, up to now globally poor, of central pain.

Comparison of two regional anesthetic techniques for knee arthroscopy.

This study compares the efficacy of "3-in-1 block" versus femoral nerve block for knee arthroscopy. One-hundred patients had a 3-in-1 block; 180 patients had a femoral nerve block. The 3-in-1 block provided anesthesia in 75 patients; 20 patients needed supplementary local anesthesia. Five patients required a general anesthesia to complete the operation. The femoral nerve block was effective in 88 patients; 90 patients needed intravenous flunitrazepam and/or fentanyl; 2 patients needed general anesthesia. The 3-in-1 block provided more satisfactory muscle relaxation and a longer postoperative analgesia than femoral nerve block. No side effects were recorded in either group. Our results suggest that the 3-in-1 block is the most effective technique of regional anesthesia for knee arthroscopy.