Search

During a 3-year period, 25 caudalis dorsal root entry zone (DREZ) operations were done for severe, facial pain. Intraoperative brainstem recordings were done before and after DREZ in all patients. Primary diagnosis included refractory trigeminal neuralgia, atypical headaches or facial pain, posttraumatic closed head injuries, postsurgical anesthesia dolorosa, multiple sclerosis, brainstem infarction, postherpetic neuralgia and cancer-related pain. At the time of discharge, good to excellent pain relief was present in 24/25 patients and fair relief in 1. At 1 month, 19/25 (76%) patients had good to excellent results and at 3 months following surgery, 17/25 (68%) continued to have good to excellent pain relief. One year following surgery, 18 patients could be evaluated, 12/18 (67%) still considered their relief as good to excellent, 2 fair and 4 poor. Transient postoperative ataxia was present in 15/25 patients (60%), but was largely resolved at 1 months. In 3/18 (17%) patients, a degree of ataxia was still present at 1 year although in none was it disabling. Two patients had transient diplopia, and 3 had increased corneal anesthesia with 1 later developing a keratitis. No surgical or postsurgical mortality was noted. This procedure has proven to be a satisfactory treatment for many patients with debilitating facial pain syndromes with acceptable morbidity.

✓ Stereotactic and functional neurosurgery has experienced a remarkable degree of development during the last 50 years, from the plaster of Paris frame of Spiegel and Wycis to the technology of frameless stereotaxis. Although predominantly used for intracranial procedures, stereotaxy has its roots in experimental studies of the spinal cord. The field of spinal cord stereotaxy has not received the same amount of attention as supratentorial surgery, but there have been significant contributions to the field that have helped to further our understanding of spinal cord anatomy and physiology. Now that frameless stereotaxis has reached clinical practice, there may be further developments in the field of spinal surgery: this technique may prove useful for spinal fusion operations and, possibly, intramedullary operations as well.

✓ This review was undertaken to determine the efficacy of using dorsal root entry zone (DREZ) lesions to treat intractable pain caused by trauma to the conus medullaris and cauda equina. Traumatic lesions of this area are unique in that both the spinal cord and the peripheral nerve roots are injured. Although DREZ lesions have been shown to relieve pain of spinal cord origin in many patients, they have been shown not to relieve pain of peripheral nerve origin. Therefore, 39 patients with trauma to the conus medullaris and cauda equina who underwent DREZ lesioning for intractable pain were reviewed retrospectively. The results of this review demonstrate the efficacy of DREZ lesions in these patients. At a mean follow-up period of 3.0 years, 54% of patients were pain-free without medications, and 20% required only nonnarcotic analgesic drugs for pain that no longer interfered with their daily activities. Better outcomes were noted in patients with an incomplete neurological deficit, with pain having an “electrical” character, and with injuries due to blunt trauma. Operative complications included weakness (four patients), bladder or sexual dysfunction (three), cerebrospinal fluid leak (two), and wound infection (two), but overall, 79.5% of patients (31 of 39) were without serious complications. Complications were limited to patients with prior tissue damage at the surgical exploration site and were most prevalent in patients who underwent bilateral DREZ lesions. In conclusion, this preliminary report suggests that DREZ lesions may be useful in combating intractable pain from traumatic injuries to the conus medullaris and cauda equina, with some risk to neurological function that may be acceptable in this group of patients.

Whereas in the early days of evil spirits, electric catfish, and phrenology, functional neurosurgery was based on crude observations and dogma, the progress made in neurophysiology at the turn of the century gave the field a strong scientific foundation. Subsequently, the advent of stereotaxis allowed access to deep brain regions and contributed an element of precision. Future directions include the development of frameless stereotaxy; the use of MRI-generated anatomic data, which would circumvent the serious problem of individual variations seen with standard brain atlases; the introduction of various chemicals into brain structures, in an attempt to influence neurochemically mediated disease processes; and finally, the use of the promising techniques of neural transplantation. On hearing of Penfield's intraoperative brain stimulations, Sherrington commented: "It must be great fun to have the physiological preparation speak to you." The idea of therapeutic neurophysiologic interventions is appealing, especially because many disorders show no obvious treatable pathologic cause (e.g., tumor, vascular malformation). As stereotactic technology becomes less cumbersome and more precise, more sophisticated in vivo neurophysiologic preparations become possible. In turn, as our understanding of nervous system physiology grows, our ability to understand pathophysiology and treat disease processes increases.

Thirty-six rats have received surgical spinal cord lesions, 7 at a thoracic and 29 at a cervical level. More than 70% of rats with lesions which involved the lateral column (spinothalamic tract) developed spontaneous dysesthesias in the contralateral limb. Only high cervical (C1-C2) lateral column lesions were followed frequently by forelimb signs. Lesions restricted to the dorsal columns were not followed by dysesthesias.

Stereotactic neurosurgery is the arena in which the past meets the present on many levels. Preserved skulls from South America, Africa, and Europe testify to man's early attempts at cranial surgery. Stereotactic approaches and systems, as well as the new innovative interactive image-guided devices, are efforts to explore and treat the afflictions of the human brain in both its literal and figurative aspects.

In his keynote address, the author presents a detailed history of the development of stereotactic and functional neurosurgery worldwide, with particular emphasis on the pioneering scientist in the field. He outlines the early days of stereotaxis in North and South America, Europe and Asia and supplements his history with an extensive list of early references (Editor''s Abstract).

Pain has been a major medical problem from the beginning of recorded history. Since the earliest medical writings, there have been innumerable procedures designed to relieve pain and its suffering. In this study, we have reviewed both the early medical writings of various civilizations and the first modern publications, to compile a history of neurosurgical procedures for the relief of pain.

To determine risk factors for dysphagia after ventral rhizotomy, videofluoroscopic barium swallowing examinations were done on 41 spasmodic torticollis patients before and after surgery. Radiologic abnormalities were present in 68.3% of the patients before surgery, but these were only mildly abnormal in the majority. After surgery 95.1% showed radiologic abnormalities which were moderate or severe in one-third of the patients. Swallowing abnormalities correlated significantly with duration of torticollis and subjective complaints of swallowing difficulty both before and after surgery, but not with age, sex, or type of torticollis. The major acute postoperative finding was aggravation of preexisting pharyngeal dysfunction. Follow-up from about half of our original sample showed that gradual improvement occurred from 4 to 24 weeks after surgery by subjective report. We review the innervation of intrinsic and extrinsic pharyngeal musculature, and suggest that C1-3 rhizotomies and selective sectioning of the spinal accessory nerve are responsible for aggravation of pharyngeal swallowing dysfunction in the acute postsurgical period.

Background and Objectives We used the MARK III free electron laser (FEL) tuned to molecular vibrational absorbance maxima in the infrared (IR) wavelength range of 3.0–6.45 μm to study the effect of these various wavelengths and a power level of 5 mJ/2 microseconds macropulse on photoablation of CNS tissue. Study Design/Materials and Methods Laser lesions were produced in the parietal cortex of anesthetized rats using thermal confined mid-IR (infrared) laser pulses tuned to the -OH, -CH, amide 1, and amide 2 absorbance bands. Histological assessments following recovery periods of 4 hours, 4 days, and 3 weeks were performed to determine the size, shape, and character of the photoablative lesions. Cell density studies were done in adjacent edematous tissue. Results Significant differences in lesion size and shape were observed as a function of wavelength. Although maximum ablation and collateral damage seemed to coincide with spectral peaks in the mid-IR, area and depth/width ratios did not. Conclusions It was found in these experiments that wavelengths in the mid-IR could be selected for optimal ablative properties. Using tunable, high-peak-power pulsed lasers, it will be possible to produce well-defined photoablative lesions that conform to small, irregularly shaped neurosurgical targets. Lasers Surg. Med. 33:81–92, 2003. © 2003 Wiley-Liss, Inc.

OBJECTIVE: Application of pulsed radiofrequency (RF) currents to the dorsal ganglion has been reported to produce long-term relief of spinal pain without causing thermal ablation. The present study was undertaken to identify spinal cord neurons activated by exposure of the dorsal ganglion to pulsed RF currents in rats. METHODS: Left-sided hemilaminectomy was performed in adult Sprague-Dawley rats to expose the C6 dorsal root ganglion. An RF electrode (0.5 mm diameter) with a thermocouple for temperature monitoring was positioned on the exposed ganglion, and rats were assigned to one of three treatment groups: pulsed RF treatment (20 ms of 500-kHz RF pulses delivered at a rate of 2 Hz for 120 s to produce tissue heated to 38°C), continuous RF (continuous RF currents for 120 s to produce tissue heated to 38°C), or sham treatment (no RF current; electrode maintained in contact with ganglion for 120 s). RESULTS: Treatment with pulsed RF but not continuous RF was associated with a significant increase in the number of cFOS-immunoreactive neurons in the superficial laminae of the dorsal horn as observed 3 hours after treatment. CONCLUSION: Exposure of the dorsal ganglion to pulsed RF currents activates pain-processing neurons in the dorsal horn. This effect is not mediated by tissue heating.

Surgical therapy of involuntary movement disorders has evolved during the past century from gross destructive ablations of the central nervous system to refined, accurate, discrete lesioning of sites deep within the brain. The understanding of neuroanatomic and physiological systems improved tremendously through experimentation in animals and empirical observations of surgery in humans. A continuum of accumulated knowledge has been achieved through ablation or lesioning of virtually all aspects of the central and peripheral nervous system predicated on previous successes or failures. This compilation of surgical history of involuntary movement disorders has provided present neurosurgeons with the foundations on which they base their therapeutic measures and will direct future endeavors within this field.

Neuropathic pain stemming from injuries within the central nervous system has proven to be recalcitrant to pharmacological and surgical therapy. Based on the observation that peripheral deafferentation led to spontaneous neuronal discharges within the dorsal horn, Loeser et al and Nashold et al set out to coagulate the substantia gelatinosa in patients who experienced phantom pain follow-ing a brachial plexus injury.26,27,36 In 1976 Nashold et al36 reported success in treating four patients. It soon became obvious that in practice these surgical lesions destroy not only the substantia gelatinosa, but also the remainder of the dorsal horn, Lissauer’s tract, and the adjacent portion of the posterior and lateral funiculi. Thus these were termed dorsal root entry zone (DREZ) lesions (Fig. 12.1.). This extended area of destruction was corroborated by postmortem studies.5

The nucleus caudalis DREZ operation has been performed in three phases at Duke. Between 1982 and 1988 radiofrequency (RF) lesions were made in the trigeminal nucleus extending from the C2 root to the obex using a straight electrode. Complications include ipsilateral arm ataxia due to spinocerebellar tract injury and ipsilateral lower limb weakness from the pyramidal tract. The former occurred at least transiently in 90% of cases. The electrode employed from 1988 to 1989 had proximal insulation protecting the spinocerebellar tract. Since 1989 a ninety degree bend has been added to the electrode to allow better placement. Two electrodes are used to accommodate the shape of the caudalis nucleus. A total of 101 procedures have been performed. The newest electrodes were used in 46 procedures. Ataxia is recognized in 39%. Overall pain relief was excellent in 34% and good in 40%. In post herpetic neuralgia 71% enjoyed excellent or good relief. Indications include post herpetic neuralgia, deafferentation pain (anaesthesia dolorosa, post-tic dysesthesia, stroke, MS, gasserian tumour, Gamma Knife radiation injury), facial trauma/surgery, atypical facial pain, and migraine/cluster headache. A study to compare this operation to deep brain stimulation prospectively for the above indications has been initiated.

✓ The fissure separating the motor from the sensory cortex and the substantia gelatinosa capping the posterior horn of the spinal cord are still known by the name of the Italian anatomist Rolando. Luigi Rolando was born in Turin, Italy, in 1773 and died in 1831. His life was not easy, the first of his problems being the death of his father when Rolando was still very young. Three people were to be influential in his life and career: Father Maffei, his maternal uncle who raised him; Dr. Cigna, the anatomy professor who discovered his talent; and Dr. Anformi, a general practitioner who introduced him to the practice of medicine and to the best circles of the city. Forced to leave Turin by the Napoleonic invasion of the country, Rolando first stopped in Florence, where he learned about anatomical dissection, drawing, and engraving and studied the appearance of nervous tissue under the microscope. Later he went to Sardinia where, although cut off from European cultural circles, he developed his major theories. Rolando pioneered the idea that brain functions could be differentiated and located in specific areas and discovered the fixed pattern of cerebral convolutions, highlighting motor and sensory gyri. He demonstrated the complexity of the central gray matter of the spinal cord, describing the “substantia gelatinosa,” and he deduced that nervous structures are connected in a network of nervous fibers linked by electrical impulses. Rolando had to struggle for recognition, however, as the priority of his discoveries was challenged by the almost contemporaneous work of Gall and Spurzheim on cerebral localization and of Flourens on cerebellar function. Nevertheless, his efforts contributed greatly to the clarification of brain function. His observations on nervous anatomy have been especially accurate, as shown by the nomenclature “fissure of Rolando” and “substantia gelatinosa of Rolando.”

The clinical pattern of torticollis and surgical results were evaluated. Head posture and range of motion were measured. The authors use a newly designed device consisting of an orthogonal system to which head position is referred. Preliminary data were obtained on 24 patients with torticollis and 21 healthy control subjects. The examination of posture shows that the head usually twists in opposite directions simultaneously around a vertical and a sagittal axis, and the deflection is greater in one direction. Head position affect body posture, with the trunk often compensating for head deviation. Although there are almost always abnormalities on EMG recordings of neck muscles, these do not indicate the degree and pattern of deformity. Because of the disorder of muscle innervation, head movements are affected, with an asymmetrical decrease in the range of motion in comparison with normals (p0.05). Movements are greater toward the direction of postural deviation. Eleven patients were studied before and after undergoing a bilateral C1-C3 rhizotomy and selective section of the XIth rootlets, which carry motor fibers to the sternocleidomastoid muscle. Head posture immediately improved (p0.05), with better appearance, despite some residual distortion (less than 10%), and trunk alignment also improved . In contrast to posture, head range of motion was worse than before (p0.05). The most improved movement was rotation, followed by flexion/extension. Further improvements were observed at later follow-up. Surprisingly, the range of motion gradually increased, surpassing preoperative limits (p0.05). Our study documents the usefulness of surgery in correcting torticollis. Posture is immediately affected; motion increases despite denervation, after an initial decline.

The results of 46 nucleus caudalis DREZ coagulations performed at Duke in the preceding 5 years are reviewed retrospectively, with a mean follow-up of 32 months. Fifteen (38%) of 39 patients with complete data indicated that they would undergo the procedure again. Fifteen (38%) described improved quality of life. Outcome was fair or better in 18 (46%). Complications in the form of ataxia were present in 21 (54%).

✓ Extensive longitudinal lesions of the dorsal root entry zone (DREZ) are effective in relieving some chronic deafferentation pain in humans. A deafferentation syndrome follows C5—T2 dorsal root ganglionectomies in rats. The syndrome consists of biting and scratching the completely and partially denervated limb areas, respectively. This study examines the effect of DREZ lesions on the deafferentation syndrome in the rat. Of 37 rats, 24 underwent C5—T2 ganglionectomies only, five received C4—T3 micromechanical DREZ lesions only, and eight underwent ganglionectomies plus simultaneous DREZ lesions. The animals were observed for 45 days postoperatively. Histological analysis of the spinal cord lesions was performed. All rats with ganglionectomies alone exhibited the deafferentation syndrome; however, no rats with DREZ lesions alone showed this feature. Only 25% of rats with combined ganglionectomies and DREZ lesions exhibited the deafferentation syndrome in the first 30 days, whereas 80% of the animals with ganglionectomies only did so. Although 75% of the animals with combined lesions eventually bit the insensitive forepaw, this behavior was significantly attenuated: the day of onset was delayed and the extent of self-mutilation was reduced. Postmortem histological examination of the DREZ lesions indicated a close association between the completeness of the dorsal horn destruction and the reduction or prevention of self-mutilation. These data support the validity of the animal model and also the hypothesis stating that the deafferentation syndrome results from abnormal spontaneous neural activity in the dorsal horn. Moreover, the variability of the histological findings in these experiments stresses the importance of making contiguous and complete dorsal horn lesions in human DREZ surgery.

✓ To determine the effects of ventral cervical and selective spinal accessory nerve rhizotomy on spasmodic torticollis, 58 patients who had undergone surgery between 1979 and 1987 were reviewed retrospectively. At the time of surgery, each nerve rootlet was electrically stimulated to determine its effect on the nuchal musculature prior to sectioning. Forty-nine patients (85%) had a marked improvement in their condition, with 33 (57%) attaining an excellent result and 16 (28%) noting significant improvement. Patients complained of abnormal head posture, nuchal muscle spasms, and pain prior to surgery. Muscle spasms were completely relieved in 42 patients (72%) and markedly reduced in 10 (17%). Of the 47 patients with preoperative pain, 30 (64%) were free of their pain and eight (17%) noted that the pain was reduced in intensity and frequency. Thirty-four patients (59%) reported that their resting head posture was restored to a neutral position. The likelihood that a patient's head posture returned to normal was inversely proportional to the preoperative duration of the spasmodic torticollis. Twenty-six patients (45%) suffered mild transient difficulty with swallowing solid foods in the immediate postoperative period. In most cases these minor difficulties abated in the months following surgery.

To explore the controversial “brainstem theory” of spasmodic torticollis, eight consecutively referred patients were examined. Three independent examinations were conducted on the same day: a videofluoroscopic barium swallowing examination, an instrumental speech examination, and a brainstem auditory-evoked potential (BAEP) analysis. Swallowing was normal in two patients; speech physiology, in five; and BAEPs, in all. Normal BAEPs refute the brainstem theory, while abnormalities of speech and swallowing temper this conclusion. Several alternative explanations are proposed.

✓ One patient with a pontine infarct due to a fusiform basilar artery aneurysm and one with an arteriovenous malformation within the tectum of the mesencephalon developed intractable facial pain. This pain was relieved in both patients by radiofrequency lesions in the dorsal root entry zone of the trigeminal nucleus caudalis.

Self-mutilation after deafferentation injuries has been reported only rarely in adult humans. This behavior has been found to be similar to that observed in animals that have been subjected to experimental deafferentation. We present a child with a brachial plexus injury sustained at birth who began to bite her analgesic digits. Self-mutilation behavior in humans is reviewed and its relevance to current deafferentation pain animal models is examined. This behavior in humans further validates the current animal model of deafferentation pain.

A deafferentation syndrome can be produced in Sprague-Dawley rats following dorsal root sections. The behavior may be objective evidence of dysesthesias, thus serving as an experimental model to study chronic dysesthesias caused by deafferentation in humans. This article examines the effects of sex, age, and lesion type on the expression of the deafferentation syndrome in Sprague-Dawley rats. No significant differences were found in the expression of the deafferentation syndrome with respect to age and weight in male rats within the ranges studied. Sex and lesion type did alter the expression of the syndrome.

New radiofrequency lesion dorsal root entry zone (DREZ) electrodes for relief of facial pain were designed based on a neuroanatomic study in man of the trigeminal nucleus caudalis at the cervicomedullary junction. The human brainstems of 3 normal postmortem specimens were sectioned with measurements and relationships of the trigeminal nucleus caudalis, segmental tracts, spinocerebellar tracts and dorsal columns. Two right-angle DREZ electrodes were made by Radionics for producing DREZ lesions in the trigeminal nucleus caudalis to treat deafferentation facial pain.

Forelimb sensorimotor (SMI) cortical lesions in the rat have been found to suppress a deafferentation syndrome which follows C5-T2 ganglionectomy/avulsion whether the cortical lesions were made prior to, or several days after, the dorsal root lesions. None of the 6 rats with only frontoparietal lesions developed a deafferentation syndrome. These results may be influenced by the presence of a sensorimotor amalgam in the parietal cortex of the rat.

Few series have analyzed the results of temporal lobectomy in the pediatric age group. In this paper, we present a child who underwent successful temporal lobectomy for medically intractable complex partial seizures at the age of three. A twenty year followup is provided. This case is significant because of the young age at which the surgery was performed, the long term followup which was obtained, and the successful result. Followup included multiple clinic visits, electroencephalograms (EEG), and psychological testing. The patient is currently seizure free and functioning well in society.

We report evaluation and results in 100 patients who had undergone anterior temporal lobectomy for intractable complex partial seizures. Average follow-up was 9.0 years (range, 2 to 21 years). In the 2nd postoperative year, 63% were seizure free, 16% were significantly improved, and 21% were considered not significantly improved. Mean number of seizures in the last group was 27% of preoperative levels. Surgical results did not change significantly in subsequent postoperative years; good outcomes tended to persist over the longer term. We also examined the utility of continuous depth electrode monitoring in the evaluation of patients with independent bitemporal interictal epileptiform activity. Despite limited numbers of subjects in this category, there was a trend toward improved surgical outcome when such subjects were evaluated with depth electrodes.

About 10% of paraplegics suffer from intractable pain. The onset of pain may be immediate or delayed for months to several years after the injury. The delayed onset of pain is highly suggestive of the development of a spinal cyst. This is a report of 18 paraplegics who developed a delayed onset of intractable pain who were found at the time of surgery to have associated spinal cord cysts. Treatment consisted of the dorsal root entry zone (DREZ) operation in addition to evacuation of the cyst. Burning pain was the most common complaint occurring years after the trauma. In this study we compared the relationship between the onset and character of the pain, the time of the spinal injury, the operative findings, and the results of the DREZ procedure and evacuation of the traumatic spinal cyst. We believe that the combination of paraplegia, pain and spinal cyst has not been emphasized in the neurosurgical literature although it is well known that cystic formation can follow spinal trauma. Two patients developed spinal cysts with nontraumatic lesions of the spinal cord. A single cyst was found in 14 patients while four had two separate cysts. The diagnosis was made on the basis of history and clinical examination with radiographic confirmation using delayed CT scan and myelography and more recently magnetic resonance imaging. Intraoperative ultrasound was employed in the study of some patients. All patients were treated with combined DREZ lesions and evacuation of the cysts with good pain relief in 77.7%.

BACKGROUND Studies suggest that the pattern of dermatomal segmental innervation in any given patient, may differ from the classic dermatomal maps first described in the 1890s. Such variability may limit the effectiveness of selective dorsal rhizotomy for treatment of neurogenic pain. CASE DESCRIPTION A 46-year-old male presented with a 27-year history of intractable pain in his left arm after being shot during the Vietnam War; multiple surgical and medical therapeutic modalities failed to produce durable pain relief. The patient underwent selective dorsal rhizotomy, with intraoperative dermatomal and mixed somatosensory evoked potential recordings. Pre- and postrhizotomy recordings were compared, effectively mapping this patient's dermatomal pattern. At 4 years' follow-up, the patient remains pain free. CONCLUSION Intraoperative monitoring of somatosensory evoked potentials during dorsal rhizotomy for neurogenic pain can be used to establish the degree to which an individual's pattern of segmental innervation conforms to the traditionally described dermatomes.

Radiation-induced brachial plexopathy (RBP) is a rare (1-2% of irradiated patients) but serious disorder associated with supramaximal irradiation of the brachial plexus. Nerve compression by radiation-induced fibrosis in the absence of tumor recurrence is the hypothesized mechanism of RBP. It appears as severe pain in up to 20% of cases. Current medical and surgical therapies are ineffective in obtaining long-term pain control. Dorsal root entry zone (DREZ) lesions represent a potential therapy for the pain associated with RBP. The records of two patients with RBP with severe pain successfully treated with DREZ lesions are reviewed. Each received supramaximal radiation to the brachial plexus following resection of the malignancy and had pain within the irradiated area approximately 1 year following radiation without evidence of tumor recurrence by either computed tomography or magnetic resonance imaging. Electromyography patterns consistent with RBP were detected within the irradiated area in both patients. Pain was in the C8-T1 distribution and described as sharp and burning. Both patients failed to obtain pain relief with prior medical and/or surgical procedures. Histologic sections of nerves were taken at surgery and confirmed the diagnosis of radiation-induced injury. Within the immediate postoperative period both patients experienced excellent pain relief and continue to be pain free at 29-48-month follow-up observation. The DREZ lesions provide a safe and effective therapy for the pain associated with RBP.

We examined the oropharyngeal swallowing ability of 43 patients with spasmodic torticollis using a videofluoroscopic procedure. Twenty-two (51.2%) demonstrated objective evidence of swallowing abnormalities; 15 (34.9%) had subjective complaints. Delayed swallowing reflex and vallecular residue were more frequent (p < 0.0046) than any other abnormality. The constellations of abnormalities were consistent with neurogenic, postural, and mixed neurogenic-postural types of dysphagia.

Unilateral dorsal rhizotomies were done at the cervicothoracic and lumbosacral spinal cord levels in rats. In preliminary experiments dermatome maps were determined for the roots to be sectioned. The behavior of 37 rats was observed for many months after the rhizotomies. The rats with the dorsal roots sectioned in the cervicothoracic spinal cord exhibited the following behavior: at the border of the skin adjacent to the zone of deafferentation, the rat scratched vigorously and progressively denuded the skin; self-mutilation of varying degrees occurred in the deafferented limb. In some animals scratching occurred in the contralateral skin dermatome opposite to the partially deafferented zone. The rats with the dorsal roots sectioned at the lumbosacral level exhibited hypersensitivity to cutaneous stimulation but there was no scratching or self-mutilation. These results are discussed in the light of previous similar research.