Sammanfattning Bakgrund: Deep brain stimulation (DBS) i nucleus ventralis intermedius i thalamus (VIM) eller caudala zona incerta (cZi) ger goda effekter på tremorsymptomen för patienter med essentiell tremor. Patienterna som behandlats med DBS kan få bieffekter som i vissa fall leder till talpåverkan, så kallad stimuleringsinducerad dysartri. Huruvida det finns risk för bieffekter som drabbar röstens funktion hos patienter med essentiell tremor saknas studier kring men man vet att grundsjukdomen kan påverka rösten akustiskt samt att vissa patienter utvecklar rösttremor. Att drabbas av en bieffekt efter DBS kan ha en inverkan på hur patienten subjektivt upplever resultatet av behandlingen.     Mål: Att undersöka om patienter med essentiell tremor som genomgått DBS subjektivt upplever någon form av röst- eller talbesvär jämfört med en frisk, ålders- och könsmatchad kontrollgrupp.   Metod: I studien deltog sammanlagt 42 deltagare varav 21 tillhörde en patientgrupp med essentiell tremor som genomgått DBS i cZi och de övriga 21 tillhörde en frisk, ålders- och könsmatchad kontrollgrupp. Deltagarna i de båda grupperna fick fylla i två formulär, RHI som berör röstens funktion och SOFT som berör talets funktion. Deltagarna som tillhörde patientgruppen fick också svara på fem fördjupande frågor om deras subjektiva upplevelse. Den statistiska signifikanstestningen genomfördes med avseende på om det fanns en skillnad i självskattningen mellan de båda grupperna.   Resultat: Resultaten i denna studie visade att patienterna med essentiell tremor s0m är behandlade med DBS skattar en signifikant större del subjektiva svårigheter av sin egen röst- och talfunktion jämfört med den friska kontrollgruppen.   Slutsats: Resultaten visade att det på gruppnivå finns signifikant större andel upplevda svårigheter relaterade till tal- och röstfunktionen hos patienter med essentiell tremor behandlade med DBS jämfört med en frisk kontrollgrupp. Resultaten visar även en stor individuell variation av den subjektiva upplevelsen av tal och röstpåverkan vilket är viktig information att delge patienter som ska genomgå DBS. Ett preoperativt samtal med logoped för information om möjliga bieffekter vid DBS och hur detta kan påverka patienten subjektivt är nödvändigt. De patienter som subjektivt upplever besvär med talet eller rösten bör erbjudas kontakt med logoped. / Abstract Background: Deep brain stimulation (DBS) of ventralis intermedius nucleus of thalamus (VIM) or caudala zona incerta (cZi) have been shown to be efficient in supressing tremor symptoms in patients with essential tremor. Patients who has been treated with DBS may acquire certain side effects of which in some cases results in an impact on the patients speech, known as stimulation- induced dysarthria. There is a lack of studies that investigate if there is a risk of side effects that is affecting voice functioning in patients with essential tremor. Previous studies have claimed that the disease itself may have an effect on the voice acoustics and that some patients develop voice tremor. The occurrence of a side effect caused by DBS may have an impact on the patients subjective experience of the treatment result.   Aim: To investigate whether patients with essential tremor treated with DBS are subjectively experiencing any form of voice or speech disability compared to a healthy, age and sex matched control group.   Method: The study included 42 participants all together whereof 21 was part of a patient group with essential tremor treated with DBS in cZi and the other 21 participants was part of a healthy, age and sex matched control group. The participants of both groups filled out two different forms, VHI (RHI) which affects voice function and SOFT which affects speech function. The participants in the patient group also answered five profound questions about their subjective experience. The test of statistical significance was performed with regard of if a difference was to be found in the self-ratings between the two groups.   Results: The results of the study show that patients with essential tremor whom have been treated with DBS rates a significantly greater amount of subjective difficulties related to the voice and speech functioning compared to the healthy control group.   Conclusion: The results show that the DBS-treated patients with essential tremor experience a significantly greater amount of subjective difficulties related to voice and speech functioning compared to a healthy control group. The results also show a great individual variety in the subjective experience of speech and voice function which is important information to notify patients who are due to undergo DBS-treatment. A preoperative meeting with a speech and language pathologist to be informed of possible side effects caused by the DBS and in what ways this can effect the patient subjectively is required. Patients who postoperatively experience a negative effect on speech or voice functioning should be offered contact with a speech and language pathologist. / Tal- och rösteffekter av djup hjärnstimulering hos patienter med ärftlig tremor

Repetitive stimulation of motor nerves causes an increase in the number of packets of transmitter ("quanta") that can be released in the ensuing period. This represents a type of conditioning, in which synaptic transmission may be enhanced by prior activity. Despite many studies of this phenomenon, there have been no investigations of the quantal mechanisms underlying these events, due to the rapid changes in transmitter output and the short time periods involved. To examine this problem, a method was developed in which estimates of the quantal release parameters could be obtained over very brief periods (3 s). Conventional microelectrode techniques were used to record miniature endplate potentials (MEPPs) from isolated frog (Rana pipiens) cutaneous pectoris muscles, before and after repetitive (40 sec at 80 Hz) nerve stimulation. Estimates were obtained of m (number of quanta released), n (number of functional release sites), p (mean probability of release) and var$\rm\sb{s}$p (spatial variance in p) using a method that employs counts of MEPPs per unit time. Fluctuations in the estimates were reduced using a moving bin technique (bin size = 3 s, $\Delta$bin = 1 s). Muscle contraction was prevented using low Ca$\sp{2+},$ high Mg$\sp{2+}$ Ringer or normal Ringer to which $\mu$-conotoxin GIIIA was added. These studies showed that: (1) the post-stimulation increase in transmitter release was dependent on stimulation frequency and not on the total number of stimulus impulses. When the total number of pulses was kept constant, the high frequency pattern produced a higher level of transmitter release than did the lower frequency patterns; (2) augmentation and potentiation were present in both low Ca$\sp{2+},$ high Mg$\sp{2+}$ and normal Ringer solutions, but potentiation, m, n, p and var$\rm\sb{s}$p were greater in normal Ringer solution than in low Ca$\sp{2+},$ high Mg$\sp{2+}$ solution. In low Ca$\sp{2+},$ high Mg$\sp{2+}$ solution, there was a larger decrease in n compared to p; (3) hypertonicity (addition of 100 mM sucrose) produced a marked increase in both basal and stimulation-induced values of m, n, and p. By contrast, there was a marked increase in the stimulation-induced but not the basal values of var$\rm\sb{s}$p; (4) hypertonicity produced a decrease in augmentation but had no effect on potentiation; (5) augmentation and potentiation appeared to involve mitochondrial uptake and efflux of cytoplasmic Ca$\sp{2+}.$ Tetraphenylphosphonium (which blocks mitochondrial Ca$\sp{2+}$ efflux and uptake) decreased augmentation and potentiation in low Ca$\sp{2+},$ high Mg$\sp{2+}$ solutions but increased potentiation in the same solution made hypertonic with 100 mM sucrose; (6) the overall findings suggest that this new method may be useful for investigating the subcellular dynamics of transmitter release following nerve stimulation.

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