By E. Ortega. Huston-Tillotson College.

For exam- to learn more about the output of spinal mo- ple cheap 30mg prevacid with visa, a force plate mounted in the ground rap- tor pools 15mg prevacid otc, are still evolving 30 mg prevacid for sale. The plate has to be camouflaged so that Figure 3–8 shows bursts from the the tibialis patients do not target their steps unnaturally cheap 30 mg prevacid mastercard. The Normally, the vertical load peaks at approxi- bursts increased in amplitude and evolved mately 110% of body weight. This vertical load more definite on and off activity as a patient curve can be unreliable, however, because it is improved in walking in relation to mass step- sensitive to motion and displacements of any ping practice. A variety of deviations from the norm have been described during hemiparetic gait. The vertical ground reaction force may reveal two SPASTICITY peaks, one at weight acceptance and push-off During hemiparetic gait, one of the typical and an intermediate trough during midstance, EMG patterns is the premature activation of as in nonparetic subjects. Some patients main- the plantarflexors as the soleus and gastrocne- tain a rather constant vertical force with three mius muscles lengthen during stance. The uninvolved leg often forward movement of the tibia as the leg pro- shows a greater vertical force after initial foot pels forward, and may cause hyperextension of contact and at push-off compared to the af- the knee. A safe typical for hemiparetic patients with stroke, method for testing patients is to have them correlated with greater spasticity by this meas- wear a chest harness attached to an overhead ure. Reducing this task-specific hyperactive lift and walk on a moving treadmill belt. The stretch reflex may improve ankle dorsiflexion oxygen and carbon dioxide contents are ana- during the stance phase in affected patients lyzed to allow the calculation of the maximum and improve walking speed, but the force ex- oxygen consumption (VO2max), the VO2 for erted by the plantarflexors at push-off is espe- a given level of work, the anaerobic thres- cially critical for improving speed. Lab- vascular efficiency of walking in adults can be 262 Common Practices Across Disorders estimated by comparing the heart rate before control the paretic trunk and leg. Isolated component movements of APPROACHES TO the step cycle may be practiced, such as weight- RETRAINING AMBULATION shifting and limb-loading. In addition, the therapy team may intervene to diminish hy- One of the foremost goals of the hemiparetic pertonicity with inhibitory exercises and try out or paraparetic patient is to achieve independ- various assistive devices such as walkers and ent ambulation. An ankle-foot orthosis may be necessary than minimal assistance to walk a short dis- to gain safe control of the ankle and knee. Oc- tance, 10 to 15 feet, by the end of their acute casionally, functional electrical stimulation is hospitalization have the most common disabil- employed to elicit ankle dorsiflexion or a ity that leads to transfer to an inpatient reha- quadriceps muscle contraction for knee con- bilitation program. Therapists often have to improvise to en- velops strategies to improve ambulation, but able patients to work around premorbid med- the entire team reinforces techniques for head ical conditions such as painful arthritis in the and trunk control, sitting and standing balance, knees to enable ambulation (Fig. The most appropriate improving stride length, swing and stance sym- targets for gait interventions are still uncertain. Therapists times, normalizing strength, and improving continue to provide physical and verbal cues to motor control. Energy consump- tion is higher with a limp than with a normal gait pattern and rises faster with an increase in Conventional Training speed. The therapist helps the patient find a functional compromise between speed, safety, Pregait training often includes neurophysio- and energy demand. The need for bracing and logic and neurodevelopmental techniques to assistive devices tends to change over the first elicit movements and develop sitting and 6 months after a stroke and over a longer pe- standing balance (see Chapter 5). Antispasticity ties include rolling or rotating at the hip to elicit medications for walking-induced symptoms flexion, as well as supine bridging, kneeling and and signs of hypertonicity such as clonus and half-kneeling. No data are available to deter- spasms are rarely needed during the inpatient mine whether or not this approach is worth the care of patients with a first stroke, but may be time and effort compared to immediately find- worth trying in patients with chronic upper mo- ing a technique that helps the patient stand and toneuron lesions. Most therapists will work to Physicians may follow patients for months or elicit selective muscle contractions and to years after formal therapy ends. Each visit is strengthen muscle groups using resistance ex- an opportunity to reevaluate the gait pattern ercises and functional exercises, such as sitting and offer adjustments to be practiced. I often on a large ball and repeated sit-to-stand move- draw upon several notions to improve walking ments. Another goal is to increase the range of skills and help establish practice parameters for motion of shortened muscles and stiff joints.

Sasaki K (1995) Magnetic resonance (2003) Differential diagnosis in patients treatment of Paget disease of bone purchase prevacid 15mg otc. Berney J (1994) Epidemiology of nar- in the course of gaseous degeneration neurosurgical sequalae of Paget disease row spinal canal buy prevacid 30mg with amex. Boden S prevacid 30mg on line, Davies DO generic prevacid 30 mg without prescription, Dina TS et al 699–704 Thickness of the human ligamentum (1990) Abnormal magnetic resonance 14. Lane WA (1893) Case of spondylolis- flavum as a function of load: an in scans of the lumbar spine in asymp- thesis associated with progressive para- vitro experimental study. Schrader P, Grob D, Rahn BA (1993) 408 al (1996) Amyloidosis related cauda Histological changes in the ligamen- 4. Orthopade 22:223–226 resonance imaging of the lumbar spine Spine 21:381–385 29. Schrader PK, Grob D, Rahm BA et al to predict low-back pain in asymptom- 16. Martinelli TA, Wiesel SW (1992) (1999) Histology of the ligamentum atic subjects: a seven-year follow-up Epidemiology of spinal stenosis. J Bone Joint Surg Am 83:1306– Course Lect 41:179–181 lumbar spinal stenosis. Douglas DL, Dugworth T, Kanis JA et al (1984) The relationship between spi- 30. Ultrasonic measurement patterns associated with permanent or treatment a vascular basis. Szpalski M, Gunzburg R (1998) The loid deposits in spinal canal stenosis. Gill GG, Manning JG, White HL Surg Br 32:325–333 tol 12:141–159 (1955) Surgical treatment of spondy- 19. J Bone (1988) Lumbar disc degeneration: cor- tom from developmental narrowing of Joint Surg Am 37:493–520 relation with age, sex and spine levels the lumbar vertebral canal. Spine 13: Joint Surg Br 36:230–237 al (2003) Clinical and psychofunc- 173–178 33. Miyamoto S, Takaoka K, Yonenobu K influence of occupation on lumbar de- compression surgery for lumbar spinal et al (1992) Ossification of the liga- generation. Videman T, Nurminen M, Troup JDG Eur Spine J 12:197–204 phogenic protein. Gutwirth P (2000) Distinguishing vas- 74:279–283 daveric material in relation to history cular disease from lumbar spinal steno- 21. Newman PH (1963) The aetiology of of back pain, occupation and physical sis. Wiltse LL, Rothman SLG (1996) Lum- Williams & Wilkins, Philadelphia, 22. Porter RW (2000) Vascular compres- bar and lumbosacral spondylolisthesis. Computed tomography after laminec- pincott Williams & Wilkins, Philadel- Saunders, Philadelphia, pp 621–654 tomy for lumbar spinal stenosis. Porter RW, Ward D (1992) cauda equina stenosis–Result of surgical treatment. Herno A, Saari T, Suomalainen O et al dysfunction: the significance of multi- J Westn Pac Orthopaedic Assoc 29: (1999) The degree of decompressive ple level pathology. Postacchini F Gumina S, Cinotti G et come in patients undergoing surgery al (1994) Ligamenta flava in lumbar for lumbar spinal stenosis. Spine 19:917–922 REVIEW Robert Gunzburg The conservative surgical treatment Marek Szpalski of lumbar spinal stenosis in the elderly Abstract Canal stenosis is now the which preserves a maximum of bony most common indication for lumbar and ligamentous structures. De- principle of surgical treatment is in- generative disc disease is by far the terspinous process distraction This most common cause of lumbar spinal device is implanted between the spin- stenosis. It is generally accepted that ous processes, thus reducing exten- surgery is indicated if a well-con- sion at the symptomatic level(s), yet ducted conservative management allowing flexion and unrestricted ax- fails. It lim- ture showed on average that 64% of its the further narrowing of the canal surgically treated patients for lumbar in upright and extended position.

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The lower part of (c) shows the Sol and TA EMG activity (average of 30 sweeps); abscissa time after heel contact cheap 30mg prevacid free shipping. The amount of reciprocal inhibition of Sol EMG during the stance phase (e) and of TA EMG during the swing phase (f ) (expressed as a percentage of the amount of inhibition observed during a voluntary contraction at equivalent EMG) is plotted against the time after heel contact buy prevacid 30 mg. This suggests that the pat- ternofafferentfeedbackcannotexplaintheobserved modulation cheap prevacid 30mg. Modulation of reciprocal Ia inhibition In the subject illustrated in Fig cheap prevacid 15mg without a prescription. Around the onset of the swing phase, stance phase of gait, and that from plantar flexors to reciprocal inhibition became greater than at rest, dorsiflexorsissmallinswing. This suggests that help ensure that antagonistic motoneurones are not transmission in the pathway of reciprocal Ia inhi- activated inappropriately during the walking cycle. Peroneal-induced inhibition of the on-going need to stabilise the ankle during the stance phase soleusEMGwasmuchsmalleratheelstrikethandur- of walking (see Chapter 11,p. It progres- sively increased through the stance phase, though always smaller than during the voluntary contrac- Studies in patients and clinical tion(Fig. Reciprocalinhibitionoftheon- implications going tibialis anterior EMG during the swing phase was similarly much smaller than during voluntary Methodology dorsiflexion (Fig. Because it is unusual reciprocal Ia inhibition for a sizeable H reflex to be recordable in tibialis (i) Presynaptic inhibition of Ia terminals on soleus anterior, peroneal-induced reciprocal Ia inhibition motoneurones is decreased during dynamic volun- ofthesoleusHreflexisusuallyexplored(however,see tary contractions of soleus but strongly increased p. Care is necessary to ensure that the condi- throughout the stance phase of walking (Chapter 8, tioning stimulus activates only the deep peroneal pp. Methodological reasons, in particular in patients with incomplete spinal cord injury who inadvertent stimulation of the superficial peroneal had recovered sufficient function to walk with some nerve,mayaccountforsomediscrepantfindings(see assistance than in healthy subjects. Tanaka & Ito (1976) found that a train of three shocks (ii) An early facilitation replacing the early inhi- totheperonealnervehadnoeffectin6of11patients bition was seen in two of four patients with incom- with hemiplegia, but produced an early inhibition in pletespinalcordinjuryandfourofthesevenpatients two patients and an early facilitation in the other withacompletespinallesionreportedbyCroneetal. Del- Perez&Field-Fote (2003)reported that, recipro- waide (1985) mentioned an early peroneal-induced cal inhibition tested at the 3-ms ISI was slightly facilitation in a few spastic patients, but gave no decreased. The absence lations show that the clear reciprocal Ia inhibi- of reciprocal inhibition on the unaffected side rep- tion observed in normal subjects was absent in the resents further evidence that spinal mechanisms patients (Fig. This is also illustrated in the are not normal on the clinically unaffected side of histogramsofFig. In patients in whom serial recordings The early facilitation that often replaces the early were obtained there was an increase in Ia inhibition inhibition could be due to Ib excitation duringtherecoveryperiodfollowingstroke,afinding not confirmed by Crone et al. It is possible that this facilitation in spastic patients could be due to the fact that a normal Ib excitation is moreeasilydisclosedbecauseofthedecreasedrecip- Patients with traumatic spinal cord injury rocal Ia inhibition. Studies in patients 231 (a) (b) Normal Spastic Corticospinal 120 100 Ia INs 80 TA Sol MN α MN Ia ISI (ms) Ia (c) Normal Spastic 40 TA Soleus 20 0 -60 -45 -30 -15 0 15 Difference between conditioned and control reflexes (% of control) Fig. Changes in reciprocal Ia inhibition of ankle muscles in patients with spasticity due to multiple sclerosis. The tonic corticospinal facilitation of tibialis anterior (TA)-coupled Ia interneurones (INs) is presumably interrupted in spastic patients (horizontal double-headed arrow). This produces both a reduction of the reciprocal Ia inhibition to soleus (Sol) motoneurones (MN), and a disinhibition of opposite soleus-coupled INs mediating reciprocal Ia inhibition to TA MNs. The size of the conditioned H reflex (expressed as a percentage of its unconditioned value) is plotted against the interstimulus interval (ISI). Average data from 74 normal subjects (●) and 39 patients with multiple sclerosis (❍). The number of subjects (expressed as a percentage of the total number of subjects in each population) is plotted against the difference between the size of the conditioned and control reflexes (expressed as a percentage of the control reflex size; negative values: inhibition, positive values: facilitation, at the 2 ms ISI). Changes during voluntary contraction soleus motoneurones (see Chapter 8,p. Themain ever, in functional terms, given the relatively weak abnormality in the patients was an absence of the sensitivity of the stretch reflex to presynaptic inhi- increase in peroneal-induced reciprocal Ia inhibi- bition of Ia terminals (see Chapter 8,pp. With the absence of modu- be a major factor in the unwanted stretch reflex lation of presynaptic inhibition of Ia terminals on activity triggered by the dynamic contraction of 232 Reciprocal Ia inhibition tibialis anterior in spastic patients (see Chapter 12, in normal subjects the excitabilities are similar (see pp. Mechanisms underlying changes in reciprocal Ia inhibition in spasticity Conclusions In normal subjects, the dominant excitatory effect Theresultsare,ingeneral,toovariabletoallowauni- of corticospinal volleys on ankle muscles is directed fying statement. However, putting aside the results to tibialis anterior (Brouwer & Ashby, 1991). If there was normally a tonic corticospinal disfacilitation of Ia interneurones to ankle extensor drive to tibialis anterior-coupled Ia inhibitory motoneurones by the corticospinal lesion removes interneurones, as exists in the baboon (Hongo et al.

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In the experiments described in this chapter buy prevacid 30mg with visa, we collected data from both eyes and recorded activity on 98 of the possible 100 electrodes cheap prevacid 30mg overnight delivery. No data were recorded on the remaining two channels because these two amplifiers had known problems order prevacid 30mg on-line. The array is connected to a connector board by 100 buy prevacid 30mg free shipping, 25-mm- diameter insulated wires. Visual Stimulus All stimuli were provided by a 17-inch computer monitor placed at the approximate visual space representation of the area centralis and 95 cm from the eye. A number of di¤erent visual stimuli were produced by software devel- oped by the authors. The stimuli used to evoke the responses described in this chap- ter were sinusoidal gratings, single drifting bars, and a random checkerboard pattern. In the case of gratings, the spatial and temporal frequencies were approximately 0. Twelve equally spaced orientations were tested between 0 and 330 degrees, where 0 degrees was defined as vertical stripes sweeping to the right and 90 degrees was defined as horizontal stripes sweeping from top to bottom. Each oriented stimulus was presented for 3 s, followed by ap- proximately 3 s of a screen uniformly lit at the background intensity. Three hundred trials were performed, giving twenty-five repeats for each orientation. The orientation for each trial was randomly assigned through a shu¿ing algo- rithm, thereby ensuring that each orientation was tested an equal number of times. The same twelve orientations were tested, but each trial consisted of 64 s of stimulation with a bar, resulting in four passes of the bar, followed by approximately 4 s of a uniformly lit screen at the background inten- sity. Only forty-eight trials were performed, representing four trials at each orienta- tion. Again, the orientation for each trial was selected by a shu¿ing algorithm. Imaging 2-D Neural Activity Patterns 47 The checkerboard pattern consisted of a number of 1:1 Â 1:1-degree squares. Using a pseudorandom number generator, each square was set to one of three inten- sities: white with 15% probability, o¤ with 15% probability, or background with 70% probability. This allowed the entire checkerboard to be shifted both vertically and horizontally by 0. A new checkerboard with a new logical screen o¤set was displayed at a rate of 25 Hz. For all stimuli, the di¤erence between the most intense white and darkest black was selected to give a 50% contrast, with the background intensity set half- way through the intensity range. Data Analysis The optimal orientation was calculated from the drifting sine wave gratings by the method described by Orban (1991). For each orientation tested, a peristimulus time histogram (PSTH) was calculated for the activity recorded on each electrode. The optimal orientation for each multiunit was selected as the orientation giving the largest firing rate for that unit. The recently introduced method of electrophysiological imaging (Diogo et al. In this method, one interpolates activity-level maps for each of the conditions tested; here it was the orientation of a drifting sine wave grating. The condition maps are then combined using the same methods used by the optical imaging community to give a single response map. Their finding that the map of activity for a single condi- tion is relatively smooth supports the validity of interpolating the condition maps. A reverse correlation method was used to estimate the receptive field size and position from the random checkerboard stimulus (Jones and Palmer, 1987; Eckhorn et al. In brief, this method performs a cross-correlation between the occur- rence of a spike and the state of each of the pixels of the computer monitor. Since there is a delay between changing the visual stimulus and the resulting spike, the cross-correlation is typically only examined over a period of 100–20 ms before the spike.

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