scholarly journals Outcomes of one-stage reconstruction for chronic multiligament injuries of knee

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Tarun Goyal ◽  
Souvik Paul ◽  
Sushovan Banerjee ◽  
Lakshmana Das
Keyword(s):  
Cruciate Ligament ◽  
Lysholm Score ◽  
Activity Level ◽  
Type Ii ◽  
Hamstring Tendons ◽  
Peroneus Longus ◽  
Type Iii ◽  
Type Iv ◽  
Ikdc Score

Abstract Purpose This article aims to evaluate patterns of chronic multiligament injuries and outcomes of treatment with single-stage reconstruction using autografts. Methods All patients with clinicoradiologically diagnosed multiligament knee injury (MKI) were included in this prospective observational study. As the time since injury was more than 6 weeks in all of the patients, they were categorized as having chronic MKI. Patients were assessed clinically for laxity, and the diagnosis was confirmed radiologically. Ipsilateral hamstring tendons were used for medial collateral ligament (MCL) or posterolateral corner reconstruction in a patient with Schenck knee dislocation (KD) type III. In these cases, the posterior cruciate ligament (PCL) and anterior cruciate ligament (ACL) were reconstructed by using the peroneus longus and contralateral hamstring tendons respectively. Ipsilateral hamstring tendons were used for ACL reconstruction and an ipsilateral peroneus longus tendon graft was used for reconstruction of the PCL in a KD type II injury. In two cases of KD type IV injury, the lateral laxity was only grade II and was managed conservatively; the rest of the ligaments were addressed like a KD type III injury. Outcome evaluation was done using a visual analogue scale (VAS) for pain, International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity level, preoperatively and postoperatively at 2 years’ follow-up. Results A total of 27 patients of mean age 33.48 ± 9.9 years with MKI were included in the study. The patients were classified as eight KD type II, 17 KD type III, and two KD type IV. The majority of the patients had associated meniscal (59.2%) or chondral (40.7%) injuries. At the 2 years’ follow-up visit, there were significant improvements in VAS score (p = 0.0001) IKDC score (p = 0.0001), Lysholm score (p = 0.0001), and range of motion (p = 0.001). None of the patients had residual laxity on clinical examination of the knee joint at the 2 years’ follow-up. All but two of the patients went back to their previous activity level. These two patients had progressive knee arthritis and needed knee arthroplasty. Conclusion Single-stage surgical reconstruction for chronic MKI has favourable functional outcomes. Level of evidence Level IV, case series.

scholarly journals Arthroscopic Transphyseal Anterior Cruciate Ligament Reconstruction in Adolescent Athletes

2016 ◽  
Vol 24 (3) ◽  
pp. 307-311 ◽  
Author(s):  
Luca Dei Giudici ◽  
Roberto Fabbrini ◽  
Luca Garro ◽  
Serena Arima ◽  
Antonio Gigante ◽  
...  
Keyword(s):  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Lysholm Score ◽  
Leg Length ◽  
Adolescent Athletes ◽  
Ikdc Score ◽  
The Mean ◽  
Anterior Cruciate ◽  
Tegner Activity Scale

Purpose To evaluate the 5-year outcome of arthroscopic transphyseal anterior cruciate ligament (ACL) reconstruction in 19 adolescent athletes. Methods 14 male and 5 female adolescent athletes aged 12 to 16 (mean, 13.9) years with Tanner stage 2 or 3 open physes underwent arthroscopic transphyseal ACL reconstruction by a single surgeon and were followed up for 5 years. Patients were evaluated using the numerical rating score (NRS) for pain, knee osteoarthritis outcome score (KOOS), International Knee Documentation Committee (IKDC) score, Tegner Activity Scale, and Lysholm Score, as well as the leg length discrepancy, femorotibial alignment, varus or valgus deformities, active and passive knee range of motion. Results At 5-year follow-up, physes were closed in all patients. The mean NRS for pain improved from 7.2 to 1.6; the KOOS improved from 55.3 to 88; the mean IKDC score improved from 34.5 to 84; the mean Tegner Activity Scale improved from 2.7 to 8.2 and was comparable with that before injury (8.4); and the mean Lysholm score improved from 36.3 to 84.6. All except 2 patients returned to their pre-injury level of sports activity after a mean of 25 weeks. The 2 exceptions had a 2+ Jerk test and a 3+ Lachman test; one of them also had positive signs for a lateral meniscal lesion. Both had sustained a second trauma not long before the 5-year follow-up. Two patients had reduced sensitivity in the anteromedial aspect of the proximal third of the tibia. One patient had leg length discrepancy of +1.5 cm owing to overgrowth response of the physis. Conclusion Transphyseal ACL reconstruction is a viable option for skeletally immature patients, with high reproducibility, a high rate of return to sport, and a low incidence of growth disturbance. Early surgery can prevent the onset of meniscal lesions and early osteoarthritis.

Increased Postoperative Manual Knee Laxity at 2 Years Results in Inferior Long-term Subjective Outcome After Anterior Cruciate Ligament Reconstruction

2018 ◽  
Vol 46 (11) ◽  
pp. 2632-2645 ◽  
Author(s):  
David Sundemo ◽  
Ninni Sernert ◽  
Jüri Kartus ◽  
Eric Hamrin Senorski ◽  
Eleonor Svantesson ◽  
...  
Keyword(s):  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Knee Laxity ◽  
Lysholm Score ◽  
Pivot Shift Test ◽  
Subjective Outcome ◽  
Kt 1000 ◽  
Ikdc Score

Background: Increased postoperative rotatory knee laxity after anterior cruciate ligament (ACL) reconstruction may be associated with an increased risk of osteoarthritis and inferior subjective outcome, although long-term studies are lacking. In terms of anteroposterior knee laxity, this association has not yet been established. Purpose/Hypothesis: The purpose was to investigate whether postoperative knee laxity is associated with inferior long-term outcome in patients who have undergone ACL reconstruction. The hypothesis was that increased laxity would cause an inferior long-term clinical and radiographic outcome. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 193 patients underwent ACL reconstruction and were examined at both 2 and 16 years postoperatively. At the 2-year follow-up, knee laxity was tested by use of the Lachman test, the anterior drawer test, the pivot-shift test, and the KT-1000 arthrometer. Outcome variables examined at the 16-year follow-up involved a radiographic assessment of osteoarthritis, patient-reported outcome measurements, and the single-legged hop test. Results: At the long-term follow-up, 147 (76%) patients were examined. The mean follow-up period for the included patients was 16.4 ± 1.2 years. A negative Lachman test at 2 years resulted in a superior International Knee Documentation Committee (IKDC) score (76.3 ± 19.4 vs 67.8 ± 19.3, P < .05) and Lysholm score (85.2 ± 11.9 vs 76.9 ± 17.8, P < .05) at the 16-year follow-up. Correspondingly, a negative anterior drawer test at 2 years was associated with a superior IKDC score (75.3 ± 18.7 vs 62.9 ± 20.2, P < .05) and Lysholm score (84.1 ± 12.1 vs 72.6 ± 20.2, P < .05) at 16 years. A negative pivot-shift test resulted in a superior IKDC score (74.5 ± 18.8 vs 46.9 ± 17.8, P < .05), a superior Lysholm score (83.3 ± 13.4 vs 58.9 ± 23.0, P < .05), and an increased level of activity (Tegner activity scale, median [range]: 4 [1-10] vs 3 [0-5], P < .05). Osteoarthritis was overrepresented in patients with positive manual knee laxity tests, but the difference was not statistically significant. The KT-1000 arthrometer result was not correlated with any outcome variables assessed in this study. Conclusion: Increased manual anteroposterior and rotatory knee laxity 2 years after ACL reconstruction is associated with an inferior long-term subjective outcome.

scholarly journals Functional Outcomes and Hop Tests Results in ACL Reconstruction Patients with Adjustable Loop Fixation: 2 Years Follow-up

2020 ◽  
Vol 8 (5_suppl5) ◽  
pp. 2325967120S0007
Author(s):  
Sholahuddin Rhatomy ◽  
Shinta Primasara ◽  
Nicolaas C. Budhiparama ◽  
Chairul Wahjudi ◽  
Riky Setyawan ◽  
...  
Keyword(s):  
Acl Reconstruction ◽  
Functional Outcomes ◽  
Cruciate Ligament ◽  
Lysholm Score ◽  
Sports Activity ◽  
Peroneus Longus Tendon ◽  
Peroneus Longus ◽  
Hop Tests ◽  
Anterior Cruciate

Background: Arthroscopic Anterior Cruciate Ligament (ACL) reconstruction is one of the most performed knee surgery, which results in early return to sport and good clinical outcomes. The outcomes are affected by various factors, namely type of grafts, graft fixation methods, tunnel orientations and diameters. If good operative results and intensive pre- and post-operative rehabilitation lead to an optimal outcome, patients can return to the pre-injury level of sports activity in the short term. Objective: Muscle strength and stability of anterior cruciate ligament in reconstructed knees have been bilaterally compared with The Peroneus Longus Tendon grafts at preoperative, 6 month and 2 years following surgery. Methods: Forty-seven patients, 40 men, and 7 women, participated in the study. The outcome measures using IKDC, Cincinnati and Tegner-Lysholm score. Hop tests were evaluated on 6th month after the surgery. Results: Results of preoperative and 2-years postoperative functional outcomes are shown the IKDC score, Tegner-Lysholm score, and Cincinnati score yielded statistically significant differences (p<0.001) between their pre- and postoperative score from 56,3% until 98,0%. The median of the hop tests were 92, 94, 94, and 95, for the single, triple, cross over, and timed tests, respectively Conclusion: In this retrospective study of 47 patients undergoing ACL reconstruction with adjustable loop fixation (GraftMax™ Button, CONMED) on the femoral site and peroneus longus tendon autograft, we found that in 2 years of follow up, the functional outcomes and hop tests were favorable. Good surgery technique and intensive pre- and post-surgery rehabilitation are very important. Six months after surgery patients are allowed to go back to sports activity.

scholarly journals Functional Outcomes and Hop Tests Results in Anterior Cruciate Ligament Reconstruction Patients with Adjustable Loop Fixation: 2-Years Follow-up

2020 ◽  
Vol 8 (A) ◽  
pp. 892-897
Author(s):  
Sholahuddin Rhatomy ◽  
Chairul Wahjudi ◽  
Thomas Edison Prasetyo ◽  
Riky Setyawan ◽  
Nicolaas C. Budhiparama
Keyword(s):  
Anterior Cruciate Ligament ◽  
Functional Outcome ◽  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Lysholm Score ◽  
Functional Score ◽  
Peroneus Longus ◽  
Hop Test ◽  
Anterior Cruciate

BACKGROUND: Grafts are ultimately integrated into the bone tunnels by either screws, cross-pins, or cortical suspension devices in anterior cruciate ligament (ACL) reconstruction. Investigation the usage of adjustable loop button is inadequate. AIM: The aim of this study was to identify knee functional outcome and serial hop test in ACL reconstruction with adjustable loop button in 2-years follow-up. METHODS: Chronic isolated ACL ruptured patients were reconstructed with adjustable loop button using peroneus longus autograft. We recorded knee functional outcome score using Tegner-Lysholm score, Modified Cincinnati score, and International Knee Documentation Committee (IKDC) at pre-operative and 2-years follow-up. Serial hop test was assessed at 6 months after surgery. RESULTS: Forty-seven patients fulfilled inclusion criteria with median age 22.0. Evaluation of functional outcome of Tegner-Lysholm score, Modified Cincinnati score, and IKDC showed significant improvement at 2-years follow-up compared to pre-operative. Serial hop test showed excellent result at 6 months after surgery. CONCLUSION: The result of knee functional score (Tegner-Lysholm score, Modified Cincinnati score, and IKDC) and serial hop test in ACL reconstruction with adjustable loop using peroneus longus autograft was excellent at 2-years follow-up. LEVEL OF EVIDENCE: Level 2, Retrospective Cohort Study.

scholarly journals Endovascular strategies for treatment of posterior communicating artery aneurysm according to angiographic architecture: Preservation vs. sacrifice of posterior communication artery

2017 ◽  
Vol 23 (6) ◽  
pp. 620-627 ◽  
Author(s):  
Jung Ho Ko ◽  
Young-Joon Kim
Keyword(s):  
Treatment Strategies ◽  
Artery Aneurysm ◽  
Posterior Communicating Artery ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Type Iv ◽  
Ischemic Complications ◽  
Type V

We report ischemic complications related to obstruction of the posterior communicating artery (PcomA) and suggest treatment strategies according to the angiographic characteristics of the PcomA and the posterior cerebral artery (PCA). Twenty-one patients with PcomA aneurysm who had initially undergone endovascular treatment and had an identifiable PcomA occlusion on immediate or follow-up angiography were enrolled. We classified PcomA aneurysm according to the characteristics of the PcomA and PCA (P1) on baseline angiography, as follows: type I was defined as PcomA aneurysm with an absent PcomA and a normal-sized P1. Type II was defined as a hypoplastic PcomA and a normal-sized P1. Type III was defined as a normal-sized PcomA and an absent P1. Type IV was defined as a normal-sized PcomA and a hypoplastic P1. Type V was a normal-sized PcomA and a normal-sized P1. Among all cases of PcomA obstruction, 15 (71.4%) were type II PcomA aneurysms, four were type IV, one was type III, and one was type V. Ischemic events related to PcomA obstruction occurred in three cases (type II, III and VI), which included two tuberothalamic infarctions (type III and IV) and one cortical infarction in the territory of the PCA (type II). Follow-up angiographies showed flow change in the PcomA in 14 cases. It is relatively safe to sacrifice type II PcomA if necessary. However, physicians should pay attention to unexpected flow changes, such as recanalization or occlusion of the PcomA, which are possible after treatment.

scholarly journals Anterior Cruciate Ligament Reconstruction With Hamstring Autograft: A Matched Cohort Comparison of the All-Inside and Complete Tibial Tunnel Techniques

2019 ◽  
Vol 7 (1) ◽  
pp. 232596711882029 ◽  
Author(s):  
Vishal S. Desai ◽  
Gregory R. Anderson ◽  
Isabella T. Wu ◽  
Bruce A. Levy ◽  
Diane L. Dahm ◽  
...  
Keyword(s):  
Physical Examination ◽  
Cruciate Ligament ◽  
Tibial Tunnel ◽  
Return To Sport ◽  
Lysholm Score ◽  
Hamstring Autograft ◽  
Tunnel Technique ◽  
Ikdc Score ◽  
Anterior Cruciate

Background: Surgical reconstruction of the anterior cruciate ligament (ACL) is one of the most common orthopaedic procedures, with an estimated 100,000 to 175,000 procedures performed annually. Recently, the all-inside reconstruction technique has come into favor and is theorized to be superior to the complete tibial tunnel technique. Purpose: To compare clinical and patient-reported outcomes (PROs) for hamstring autograft ACL reconstruction (ACLR) performed with an all-inside versus a complete tibial tunnel technique. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent hamstring autograft ACLR via either an all-inside approach (femoral and tibial sockets) or a complete tibial tunnel approach (femoral socket and full-length, transtibial tunnel) at a single institution between July 2011 and July 2015 were reviewed. Demographic information, preoperative comorbidities, surgical details, physical examination findings, and follow-up outcomes were extracted from the medical record. Physical examination data included pivot-shift, Lachman, and range of motion examinations, whereas PROs included the Tegner activity scale, Lysholm score, and International Knee Documentation Committee (IKDC) score at a minimum of 2 years after surgery. Return to sport and risk factors for failure were analyzed. Results: A total of 82 patients (mean ± SD age, 25.8 ± 10.2 years) who underwent all-inside reconstruction (median PRO follow-up, 30.1 months; range, 24.7-72.9 months) and 54 patients (mean ± SD age, 21.1 ± 7.3 years) who underwent complete tibial tunnel reconstruction (median PRO follow-up, 25.8 months; range, 23.9-74.5 months) met the inclusion criteria. PRO scores at latest follow-up were comparable between the all-inside versus the complete tibial tunnel groups (Lysholm score, 93.8 vs 94.4, P = .621; IKDC score, 93.5 vs 93.3, P = .497; Tegner activity score, 6.4 vs 6.8, P = .048). Complications (including graft failure) were experienced by 20% of patients in the all-inside group compared with 24% in the complete tibial tunnel group ( P = .530). Graft failure before the final follow-up was experienced by 10% of patients in the all-inside group compared with 19% in the complete tibial tunnel group ( P = .200). Mean return to sport was 12.5 months in the all-inside group versus 9.9 months in the complete tibial tunnel group ( P = .028). Conclusion: All-inside and complete tibial tunnel hamstring autograft ACLR resulted in excellent physical examination findings and PROs at minimum 2-year follow-up. Both techniques successfully restored knee stability and patient function.

Labelling of non-A, non-B hepatitis infected chimpanzee hepatocytes with nuclease-gold conjugates

1984 ◽  
Vol 42 ◽  
pp. 250-251
Author(s):  
G. D. Gagne ◽  
M. F. Miller ◽  
D. A. Peterson
Keyword(s):  
Endoplasmic Reticulum ◽  
Experimental Infection ◽  
Uranyl Acetate ◽  
Type I ◽  
Cellular Injury ◽  
Type Ii ◽  
Tubular Structures ◽  
Type Iii ◽  
Type Iv ◽  
Infected Chimpanzee

Experimental infection of chimpanzees with non-A, non-B hepatitis (NANB) or with delta agent hepatitis results in the appearance of characteristic cytoplasmic alterations in the hepatocytes. These alterations include spongelike inclusions (Type I), attached convoluted membranes (Type II), tubular structures (Type III), and microtubular aggregates (Type IV) (Fig. 1). Type I, II and III structures are, by association, believed to be derived from endoplasmic reticulum and may be morphogenetically related. Type IV structures are generally observed free in the cytoplasm but sometimes in the vicinity of type III structures. It is not known whether these structures are somehow involved in the replication and/or assembly of the putative NANB virus or whether they are simply nonspecific responses to cellular injury. When treated with uranyl acetate, type I, II and III structures stain intensely as if they might contain nucleic acids. If these structures do correspond to intermediates in the replication of a virus, one might expect them to contain DNA or RNA and the present study was undertaken to explore this possibility.

scholarly journals Perforator preservation technologies (PPT) based on a new neuro-interventional classification in endovascular treatment of perforator involving aneurysms (piANs)

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chen Li ◽  
Ao-Fei Liu ◽  
Han-Cheng Qiu ◽  
Xianli Lv ◽  
Ji Zhou ◽  
...  
Keyword(s):  
Endovascular Therapy ◽  
Saccular Aneurysm ◽  
Type I ◽  
Type Ii ◽  
Fusiform Aneurysm ◽  
Type Iii ◽  
Perforating Artery ◽  
Protection Technology ◽  
Perforating Arteries

Abstract Background Treatment of perforator involving aneurysm (piAN) remains a challenge to open and endovascular neurosurgeons. Our aim is to demonstrate a primary outcome of endovascular therapy for piANs with the use of perforator preservation technologies (PPT) based on a new neuro-interventional classification. Methods The piANs were classified into type I: aneurysm really arises from perforating artery, type II: saccular aneurysm involves perforating arteries arising from its neck (IIa) or dome (IIb), and type III: fusiform aneurysm involves perforating artery. Stent protection technology of PPT was applied in type I and III aneurysms, and coil-basket protection technology in type II aneurysms. An immediate outcome of aneurysmal obliteration after treatment was evaluated (satisfactory obliteration: the saccular aneurysm body is densely embolized (I), leaving a gap in the neck (IIa) or dome (IIb) where the perforating artery arising; fusiform aneurysm is repaired and has a smooth inner wall), and successful perforating artery preservation was defined as keeping the good antegrade flow of those perforators on postoperative angiography. The periprocedural complication was closely monitored, and clinical and angiographic follow-ups were performed. Results Six consecutive piANs (2 ruptured and 4 unruptured; 1 type I, 2 type IIa, 2 type IIb, and 1 type III) in 6 patients (aged from 43 to 66 years; 3 males) underwent endovascular therapy between November 2017 and July 2019. The immediate angiography after treatment showed 6 aneurysms obtained satisfactory obliteration, and all of their perforating arteries were successfully preserved. During clinical follow-up of 13–50 months, no ischemic or hemorrhagic event of the brain occurred in the 6 patients, but has one who developed ischemic event in the territory of involving perforators 4 h after operation and completely resolved within 24 h. Follow-up angiography at 3 to 10M showed patency of the parent artery and perforating arteries of treated aneurysms, with no aneurysmal recurrence. Conclusions Our perforator preservation technologies on the basis of the new neuro-interventional classification seem feasible, safe, and effective in protecting involved perforators while occluding aneurysm.

scholarly journals Brachial supporting structure of Spiriferida (Brachiopoda)

2020 ◽  
pp. 1-15
Author(s):  
Zhiwei Yuan ◽  
Wen Guo ◽  
Dan Lyu ◽  
Yuanlin Sun
Keyword(s):  
Mantle Cavity ◽  
Family Type ◽  
Type I ◽  
Type Ii ◽  
Feeding Apparatus ◽  
Single Family ◽  
Supporting Structure ◽  
Type Iii ◽  
Type Iv ◽  
Evolutionary Lineages

Abstract The filter-feeding organ of some extinct brachiopods is supported by a skeletal apparatus called the brachidium. Although relatively well studied in Atrypida and Athyridida, the brachidial morphology is usually neglected in Spiriferida. To investigate the variations of brachidial morphology in Spiriferida, 65 species belonging to eight superfamilies were analyzed. Based on the presence/absence of the jugal processes and normal/modified primary lamellae of the spiralia, four types of brachidium are recognized. Type-I (with jugal processes) and Type-II (without jugal processes), both having normal primary lamellae, could give rise to each other by losing/re-evolving the jugal processes. Type-III, without jugal processes, originated from Type-II through evolution of the modified lateral-convex primary lamellae, and it subsequently gave rise to Type-IV by evolving the modified medial-convex primary lamellae. The evolution of brachidia within individual evolutionary lineages must be clarified because two or more types can be present within a single family. Type-III and Type-IV are closely associated with the prolongation of the crura, representing innovative modifications of the feeding apparatus in response to possible shift in the position of the mouth towards the anterior, allowing for more efficient feeding on particles entering the mantle cavity from the anterior gape. Meanwhile, the modified primary lamellae adjusted/regulated the feeding currents. The absence of spires in some taxa with Type-IV brachidium might suggest that they developed a similar lophophore to that in some extant brachiopods, which can extend out of the shell.

Response properties of units in the dorsal cochlear nucleus of unanesthetized decerebrate gerbil

1996 ◽  
Vol 75 (4) ◽  
pp. 1411-1431 ◽  
Author(s):  
K. A. Davis ◽  
J. Ding ◽  
T. E. Benson ◽  
H. F. Voigt
Keyword(s):  
Dorsal Cochlear Nucleus ◽  
Type I ◽  
Type Ii ◽  
Decerebrate Cat ◽  
Excitatory Response ◽  
Type Iii ◽  
Type Iv ◽  
Noise Type ◽  
Rate Versus ◽  
Excitatory Responses

1. The electrophysiological responses of single units in the dorsal cochlear nucleus of unanesthetized decerebrate Mongolian gerbil (Meriones unguiculatus) were recorded. Units were classified according to the response map scheme of Evans and Nelson as modified by Young and Brownell, Young and Voigt, and Shofner and Young. Type II units have a V-shaped excitatory response map similar to typical auditory nerve tuning curves but little or no spontaneous activity (SpAc < 2.5 spikes/s) and little or no response to noise. Type I/III units also have a V-shaped excitatory map and SpAc < 2.5 spikes/s, but have an excitatory response to noise. Type III units have a V-shaped excitatory map with inhibitory sidebands, SpAc > 2.5 spikes/s, and an excitatory response to noise. Type IV-T units typically also have a V-shaped excitatory map with inhibitory sidebands, but have a highly nonmonotonic rate versus level response to best frequency (BF) tones like type IV units, SpAc > 2.5 spikes/s, and an excitatory response to noise. Type IV units have a predominantly inhibitory response map above an island of excitation of BF, SpAc > 2.5 spikes/s, and an excitatory response to noise. We present results for 133 units recorded with glass micropipette electrodes. The purpose of this study was to establish a normative response map data base in this species for ongoing structure/function and correlation studies. 2. The major types of units (type II, type I/III, type III, type IV-T, and type IV) found in decerebrate cat are found in decerebrate gerbil. However, the percentage of type II (7.5%) and type IV (11.3%) units encountered are smaller and the percentage of type III (62.4%) units is larger in decerebrate gerbil than in decerebrate cat. In comparison, Shofner and Young found 18.5% type II units, 30.6% type IV units, and 23.1% type III units using metal electrodes. 3. Two new unit subtypes are described in gerbil: type III-i and type IV-i units. Type III-i units are similar to type III units except that type III-i units are inhibited by low levels of noise and excited by high levels of noise whereas type III units have strictly excitatory responses to noise. Type IV-i units are similar to type IV units except that type IV-i units are excited by low levels of noise and become inhibited by high levels of noise whereas type IV units have strictly excitatory responses to noise. Type III-i units are approximately 30% of the type III population and type IV-i units are approximately 50% of the type IV population. 4. On the basis of the paucity of classic type II units and the reciprocal responses to broadband noise of type III-i and type IV-i units, we postulate that some gerbil type III-i units are the same cell type and have similar synaptic connections as cat type II units. 5. Type II and type I/III units are distinguished from one another on the basis of both their relative noise response, rho, and the normalized slope of the BF tone rate versus level functions beyond the first maximum. Previously, type II units were defined to be those nonspontaneously active units with rho values < 0.3 where rho is defined as the ratio of the maximum noise response minus spontaneous rate to the maximum BF tone response minus spontaneous rate. In the gerbil, the average rho value for type II units is 0.25, although a few values are > 0.3, and the rate-level curves are consistently nonmonotonic with normalized slopes steeper than than -0.007/dB. The average rho value for type I/III units is 0.54, although a few values are < 0.3, and the rate-level curves tend to saturate with slopes shallower than -0.006/dB. In general, the response properties of type II units recorded in gerbil are similar to those recorded in decerebrate cat. 6. In comparison to decerebrate cat, the lower percentage of type IV units recorded in decerebrate gerbil may be due to a species difference (a reduced number of type II units in gerbil) or an electrode bias.

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