Cerebellar voice tremor: an acoustic analysis.

Patients with cerebellar disease may exhibit tremulous phonation as part of their dysarthria. The results of an acoustic analysis of cerebellar voice tremor in a patient with hereditary ataxia and presenting with a purely cerebellar syndrome are reported. Analysis included computation of speech intensity contours, fundamental frequency contours, and spectral parameters from sustained productions of vowels and voiceless fricatives. Fundamental frequency contours during sustained phonation of vowels showed rhythmic oscillations at a rate of about 3 Hz. No concomitant periodicity could be detected for the parameters characterising voiceless fricative production. The results indicate an impairment of phonatory control in relation to the maintenance of a constant isometric activity of the internal laryngeal muscles. Cerebellar voice tremor may therefore be classified as a form of postural tremor.     

Stereotaxic brain puncture. Indications and results

228 stereotactic biopsies for the diagnosis of brain lesions were evaluated. In 98.2% a diagnosis could be established. The diagnosis was made of brain tumor in 79.3%, of brain abscess in 7.5% and of encephalitis in 3.5% of cases. In 2.2% of the patients a pathological finding was obtained without a clear histological definition. No histological diagnosis could be made in 1.8% of the patients. A severe complication of brain biopsy occurred in 2.2% of the patients (1 death, 1 abscess, 3 increased impairments). The stereotactic procedure appears to have a low mortality and morbidity, and to be highly accurate.     

Neural timing nets.

Formulations of artificial neural networks are directly related to assumptions about neural coding in the brain. Traditional connectionist networks assume channel-based rate coding, while time-delay networks convert temporally-coded inputs into rate-coded outputs. Neural timing nets that operate on time structured input spike trains to produce meaningful time-structured outputs are proposed. Basic computational properties of simple feedforward and recurrent timing nets are outlined and applied to auditory computations. Feed-forward timing nets consist of arrays of coincidence detectors connected via tapped delay lines. These temporal sieves extract common spike patterns in their inputs that can subserve extraction of common fundamental frequencies (periodicity pitch) and common spectrum (timbre). Feedforward timing nets can also be used to separate time-shifted patterns, fusing patterns with similar internal temporal structure and spatially segregating different ones. Simple recurrent timing nets consisting of arrays of delay loops amplify and separate recurring time patterns. Single- and multichannel recurrent timing nets are presented that demonstrate the separation of concurrent, double vowels. Timing nets constitute a new and general neural network strategy for performing temporal computations on neural spike trains: extraction of common periodicities, detection of recurring temporal patterns, and formation and separation of invariant spike patterns that subserve auditory objects.     

Post-lumbar puncture headaches: experience in 501 consecutive procedures.

To ascertain the frequency and risk factors for post-lumbar puncture headache, we studied all adults who had an ambulatory lumbar puncture (LP) in a 1-year period. Patients filled out a questionnaire detailing their headache experience on the day of, and the 6 days following, LP. Those who did not return the questionnaire were telephoned. We systematically collected and analyzed many items, including the lumbar puncturist's experience, the degree of difficulty of the LP, CSF findings, final diagnosis, and the patient's demographic characteristics. Patients reporting headache before LP were more likely to report post-LP headaches. In addition to this, younger female patients with a lower body mass index have the highest risk of developing post-LP headaches. CSF opening pressure, cells, and protein, patient's position during LP, the duration of recumbency following LP, and the amount of CSF removed at the time of LP did not influence the occurrence of headache.     

斜向立体定向穿刺法与垂直立体定向穿刺法的对比研究

目的通过对比斜向立体定向穿刺法与垂直立体定向穿刺法的准确性、安全性的差别,探讨斜向立体定向穿刺法替代垂直立体定向穿刺法的可能性。方法雄性SD大鼠12只,分别采用斜向(左,20°)及垂直(右)立体定向穿刺法穿刺丘脑前核。穿刺后10小时行7.0T头部核磁共振检查,对比两种方法上矢状窦破裂发生率、穿刺针道与丘脑前核长轴所成夹角大小以及穿刺最深点位于丘脑前核内比例的差别。所有统计结果采用均数±标准差表示,用SPSS19.0医学统计程序进行配对样本t检验,P<0.05有统计学差异,P<0.01有显著性差异。结果斜向立体定向穿刺未出现上矢状窦破裂,垂直立体定向穿刺有3例发生上矢状窦破裂出血(25.0%)。斜向穿刺针道与丘脑前核长轴夹角为10.1±2.1度,垂直穿刺针道与丘脑前核长轴夹角为29.7±3.0度,斜向穿刺针道与丘脑前核长轴重合度更高(P<0.01)。斜向穿刺最深点位于丘脑前核内比例为58.3%(7/12),垂直穿刺最深点位于丘脑前核内比例为66.7%(8/12),两者穿刺准确性无统计学差异(P>0.05)。结论斜向立体定向穿刺法在安全性上优于垂直立体定向穿刺法,且通过选择适当角度可使穿刺针道与核团长轴重合度更高,两者准确性没有区别,因此前者更适合于动物实验中进行立体定向穿刺。     

Assessment of voice stress in children.

An assessment of voice stress in two children presenting for psychiatric treatment is accomplished through the use of a new instrument called the Psychological Stress Evaluator (PSE-1). It is designed to measure the audible and inaudible voice frequencies whose strengths and patterns relate inversely to the degree of psychological stress in the voice of the speaker. Stressful responses were found in 1-hour recordings of psychiatric interviews with these two children and data analysis was organized into three major categories: content of communication, responses to therapist-posed questions, and miscellaneous responses not included in the other two categories.     

The pharmacological treatment of voice disorders.

The increasing diversity of purpose-built, synthetic and biogenetically engineered pharmaceuticals has led to a revival of interest in the pharmacological possibilities for the treatment of voice disorders. Where dysphonias arise as a part of a pathophysiological process, the pharmacological treatment of either the pathology or its associated symptoms may improve dysphonic voicing patterns. The treatment of symptoms such as cough and vocal fatigue are discussed together with treatment of allergic and other causes of inflammation or stiffening of the vocal tract. The pharmacological logical treatment of dysphonia due to defective neuromuscular control in dyskinetic and dystonic conditions is also discussed. Dysphonic voicing patterns are commonly multifactorial, and the author wishes to highlight problems encountered when attempting to adjust the performance of the vocal tract: imprecise targeting of the pathophysiological problems either by the physician or by the drug employed, and the systemic and attendant side-effects of drugs which may be thought to be appropriate.     

Agrammatism in Tagalog: voice and relativisation

Background: Virtually nothing is known about the ability of Tagalog speakers with agrammatic aphasia to cope with basic grammatical features of their language. Tagalog is unusual in exhibiting competing transitive patterns thanks to a system of voice that can make either of the verb’s arguments syntactically prominent – a prerequisite for undergoing syntactic operations such as relativisation.

Aims: Our objective is to investigate the nature of the syntactic impairment associated with agrammatic aphasia in Tagalog, with special attention to voice patterns and relative clauses (RCs).

Methods and Procedures: Five native Tagalog-speaking patients diagnosed with agrammatism took part in (1) elicited-production and (2) comprehension tasks to assess their ability with respect to voice patterns and (3) elicited-production, (4) imitation, and (5) comprehension tasks to assess their performance on RCs.

Outcomes and Results: Although the participants did poorly on grammatical morphemes, the classic symptom of agrammatism, their impairment was somewhat less severe in patterns involving verb–agent–patient order, the patient-voice in declarative clauses, and the agent voice in RCs.

Conclusions: Our findings reveal a departure from a general cross-linguistic tendency to favour agent-prominent constructions (e.g., the active voice in languages like English), as shown by the participants’ greater accuracy on patient voice declaratives than on their agent voice counterparts. Nonetheless, we found evidence of a subject preference in RCs, consistent with reports of a similar advantage in many other languages.     

Auditory processing of interaural timing information: new insights.

Differences in the time-of-arrival of sounds at the two ears, or interaural temporal disparities (ITDs), constitute one of the major binaural cues that underlie our ability to localize sounds in space. In addition, ITDs contribute to our ability to detect and to discriminate sounds, such as speech, in noisy environments. For low-frequency signals, ITDs are conveyed primarily by "cycle-by-cycle" disparities present in the fine-structure of the waveform. For high-frequency signals, ITDs are conveyed by disparities within the time-varying amplitude, or envelope, of the waveform. The results of laboratory studies conducted over the past few decades indicate that ITDs within the envelopes of high-frequency are less potent than those within the fine-structure of low-frequency stimuli. This is true for both measures of sensitivity to changes in ITD and for measures of the extent of the perceived lateral displacement of sounds containing ITDs. Colburn and Esquissaud (1976) hypothesized that it is differences in the specific aspects of the waveform that are coded neurally within each monaural (single ear) channel that account for the greater potency of ITDs at low frequencies rather than any differences in the more central binaural mechanisms that serve these different frequency regions. In this review, the results of new studies are reported that employed special high-frequency "transposed" stimuli that were designed to provide the high-frequency channels of the binaural processor with envelope-based information that mimics waveform-based information normally available only in low-frequency channels. The results demonstrate that these high-frequency transposed stimuli (1) yield sensitivity to ITDs that approaches, or is equivalent to, that obtained with "conventional" low-frequency stimuli and (2) yield large extents of laterality that are similar to those measured with conventional low-frequency stimuli. These findings suggest that by providing the high-frequency channels of the binaural processor with information that mimics that normally available only at low frequencies, the potency of ITDs in the two frequency regions can be made to be similar, if not identical. These outcomes provide strong support for Colburn and Esquissaud's (1976) hypothesis. The use of high-frequency transposed stimuli, in both behavioral and physiological investigations offers the promise of new and important insights into the nature of binaural processing.     

Human brain potential correlates of voice priming and voice recognition

This study investigated repetition priming in the recognition of famous voices, recording reaction times (RTs) and event-related brain potentials (ERPs). In Experiment 1, a facilitation was found in RTs to famous but not to unfamiliar voices when these had been primed by a different voice sample of the same speaker earlier in the experiment. However, ERPs to both famous and unfamiliar voices showed repetition priming in terms of an increased P2 component, which is thought to be generated in the auditory cortex. When the likelihood of conscious retrieval of primes was reduced in Experiment 2, facilitatory priming in RTs was again observed for famous voices, but inhibitory priming was now observed for unfamiliar voices. This is consistent with predictions of a bias model of priming. Moreover, substantial priming was observed even when voice primes were backward speech samples, which were recognised at chance levels. The results suggests that (a) voice priming is mediated to a large extent by frequency characteristics of a particular voice, rather than by articulatory and other 'sequential' features that are eliminated in backward speech; (b) priming affects the processing of voices in auditory cortical areas within 200 ms after voice onset; and (c) explicit recognition of a voice in the priming phase is not a necessary condition for priming to occur.     

Abducens palsy after lumbar puncture.

OBJECTIVE: We report the case of a 43-year-old patient with neuralgic shoulder amyotrophy who developed abducens palsy on the left 4 days after diagnostic lumbar puncture (LP), which recovered completely within 4 months. RESULTS: Side effects after spinal tap are due to prolonged spinal fluid leakage and delayed closure of a dural defect causing intracranial hypotension. Downward 'sagging' of the brain and traction on cranial nerves may lead to abducens palsy. This case and a review of the literature illustrate the higher risk with the use of large-size traumatic needles in LP for cranial sixth nerve palsies. CONCLUSION: The presented case emphasizes the use of atraumatic small-size needles for lumbar puncture.     

The pathophysiology of lumbar puncture headache.

The pathophysiology of lumbar puncture headache (LPH) is still unclear. There is evidence that leakage of cerebrospinal fluid (CSF) leads to CSF hypotension, which causes dilation of intracranial veins, resulting in LPH. However, CSF leaks at the skull base are not associated with orthostatic headache; there is poor correlation between recumbent CSF pressure and LPH; and there has been no satisfactory explanation of how venous dilation causes orthostatic headache. We propose the hypothesis that LPH is caused by an abnormal distribution of craniospinal elasticity. Increased compliance at the lumbar end of the spinal CSF space, resulting both from anatomic joining of the subarachnoid to the epidural space and from reduced CSF filling pressure, causes the hydrostatic indifferent point to move caudally, creating additional intracranial hypotension and venous dilation in the erect position. We are, thus, able to explain the orthostatic character of LPH, the fact that spinal but not cranial sites of leakage produce orthostatic headache and the imperfect correlations both between recumbent CSF pressure and LPH and between reduced CSF volume and LPH. The near absence of LPH in the very young and in the elderly relates to the relative stiffness of the epidural space at these ages. Epidural injections of blood or saline give immediate relief by reducing epidural distensibility.