Hilmi Uysal

Effect of temperature on electrophysiological parameters of swallowing.

The effect of three different temperature ranges on the triggering of voluntary-induced swallowing and on the duration of the pharyngeal phase of oropharyngeal swallowing was studied electrophysiologically. The relationship between volume and temperature of liquids swallowed was also explored. This study included 40 nondisabled volunteers (23 male and 17 female). Laryngeal vertical movements and submental electromyographic activity were recorded as each subject swallowed water at three different temperature ranges: normal (23-25 degrees C), cold (8-10 degrees C), and hot (58-60 degrees C). The time for triggering of the pharyngeal phase of swallowing was found to be shorter for cold and hot water than for normal temperature water (p < 0.01). The duration of the pharyngeal phase of oropharyngeal swallowing was also shorter for cold and hot water than for normal temperature water (p < 0.05). The maximum capacity of a single bolus (dysphagia limit) was >20 mL of water in all nondisabled subjects for different temperatures. However, the capacity was significantly less for hot water relative to normal temperature water and cold water (p < 0.05). In conclusion, the temperature ranges used in this study were found to be effective in triggering voluntary-induced swallowing.

Effects of sex and age on strength-duration properties.

OBJECTIVE To evaluate the possible effects of sex and age on strength-duration time constant (SDTC). METHODS The SDTC of 126 healthy volunteers was measured following stimulation of right median nerve at the wrist. Variations in values were evaluated according to sex and age. RESULTS The SDTC was 438.6+/-114.5 micros in women and 396.2+/-90.3 in men (P=.023). In men, as age increased, so did SDTC. However, this was not true in women. Comparing the values of women and men, aged below 40, demonstrated a difference in excitability, confined to younger patients. CONCLUSIONS As SDTC depends on the biophysical properties of the axonal membrane and can provide some information about Na(+) channel function, these data raise the possibility of a difference in Na(+) channel function between men and women and a difference in the conductance with age. SIGNIFICANCE The age- and sex-related differences shown in this study suggest a possible biochemical or hormonal influence on axonal excitability.

Strength–duration properties of sensory and motor axons in alcoholic polyneuropathy

Abstract Objective: The strength–duration time constant (SDTC) is a measure of axonal excitability and depends on the biophysical properties of the axonal membrane. The strength–duration time constant can provide information about Na+ channel function. We aimed to examine changes in the SDTCs of motor and sensory fibers in the median nerves in patients with alcoholic polyneuropathy. Methods and results: We measured the SDTCs of motor and sensory fibers in 17 patients with alcoholic polyneuropathy (15 men and two women) after stimulating the right median nerve at the wrist. The results were compared with ten healthy age-matched subjects (six men and four women). In patients, the SDTC and rheobase for the motor fibers were 370.8 ± 97.4 μs and 3.9 ± 1.7 mA; for the sensory fibers, the SDTC and rheobase were 464.7 ± 104.3 μs and 3.3 ± 1.9 mA. In controls, the SDTC and rheobase for the motor fibers were 359.3 ± 103.5 μs and 3.5 ± 1.9 mA; for the sensory fibers, the SDTC and rheobase were 478.9 ± 113.9 μs and 2.1 ± 1.5 mA. Sensory fibers had significantly longer SDTCs and lower rheobase than motor fibers in patients and controls. However, when the values of the patients and controls were compared, a statistically significant difference was only found for the rheobase of sensory fibers (p=0.037). Conclusions: Although alcoholic neuropathy corresponds to the pattern of axonopathy, it did not act on the SDTC of the median nerve, which depends on the biophysical properties of the axonal membrane at the node of Ranvier. The process causing axonal degeneration in alcoholic neuropathy may affect internodal channels other than nodal channels or the Na+ –K+ ATP pump.

Effect of cold application and tizanidine on clonus: clinical and electrophysiological assessment.

Abstract Background/Objectives: Clonus is an involuntary rhythmic muscle contraction after sudden muscle stretch that occurs as a result of a lesion in the upper motor neurons. The real mechanism behind clonus remains obscure. The objective of this study was to investigate the effects of central-acting tizanidine treatment and peripheral extremity cooling on clonus. Participants: Thirty-eight patients with upper motor neuron involvement and sustained clonus. Methods: The 38 patients were divided into 3 groups: cold group (n = 19), tizanidine group (n = 13), and patient control group (n = 6). A separate group of 21 able-bodied volunteers served as controls for the cold group. The physiologic effects of cold application were measured in the able-bodied group and compared with the effects in the patients in the cold group. All participants were evaluated by clinical and electrophysiologic measurements. Results: Changes in clinical and electrophysiologic measurements in the cold group were statistically significant compared with those of the tizanidine and patient control groups. Conclusions: Subsequent and long-term cold application induced prolonged inhibitory effects on clonus. Tizanidine had no significant effect on clonus. Suppression of clonus by cold highlights the importance of peripheral input in relation to central mechanisms.

Spasticity: From Pathophysiology to Clinical Practice

Spasticity is a movement disorder developing after an upper motor neuron lesion. It consists of velocityrelated muscle tonus increase and thus it affects the daily lives of the patients. Spasticity is quite a common disorder and can develop due to various kinds of lesions in the brain and spinal cord. Although spasticity is a well-known clinical entity, its definition, assessment and measurement create challenges for researchers in this field.

Flexor reflexes elicited by magnetic and electric stimulation of the sural nerve

Abstract Objectives: We have investigated whether magnetic stimulation of the sural nerve can evoke a flexor reflex recorded from the ipsilateral short head of the biceps femoris muscle. Methods: The sural nerve was subjected to magnetic stimulation as well as by single-pulse electrical stimulation in healthy subjects. Results: In 87% of the participants, a reflex response was elicited from the short head of biceps femoris muscle by magnetic stimulation of the sural nerve. In terms of latency and amplitude, this reflex response was similar to the flexor reflex response evoked from the same muscle by single-pulse electrical stimulation of the sural nerve. Discussion: Findings indicate that flexor reflexes can easily be evoked from the short head of the biceps femoris muscle by magnetic stimulation of the sural nerve. The late component of the flexor reflex may not only be elicited via nociceptive afferents but may also involve non-nociceptive afferents.