A novel method to measure sensory nerve conduction of the posterior antebrachial cutaneous nerve.

INTRODUCTION/AIMS: Posterior antebrachial cutaneous (PABC) nerve conduction studies could be useful for distinguishing PABC neuropathy from C7 radiculopathy. In the conventional method using an antidromic method, the sensory nerve action potential (SNAP) is sometimes followed by a large volume-conducted motor potential. In this report we describe a reliable nerve conduction study using an orthodromic method for recording SNAPs of the PABC nerve. METHODS: Thirty-six healthy volunteers participated in this study. PABC SNAPs were recorded by placing a surface-active electrode 2 cm anterior to the lateral epicondyle. The PABC nerve was stimulated 10 cm distal to the active recording electrode along a line from the recording point to the mid-dorsum of the wrist, midway between the radial and ulnar styloid processes. We also performed PABC nerve conduction studies using an antidromic method and compared the findings. RESULTS: PABC SNAPs were recorded bilaterally from all subjects. The mean peak-to-peak amplitude for SNAPs was 13.4 ± 4.8 µV. Mean maximum conduction velocity was 62.7 ± 3.9 m/s and mean negative peak conduction velocity was 51.2 ± 2.6 m/s. The mean side-to-side difference in amplitude was 22.1 ± 16.0%. The mean amplitude of SNAPs obtained by our method was 48.9% higher than that of SNAPs obtained by the conventional method (13.4 vs 9.0 µV; P < .001). In contrast to the conventional method, our method enabled SNAPs to be recorded without a volume-conducted motor potential. DISCUSSION: The higher mean amplitude of SNAPs with our method enables them to be obtained easily.

Anatomical variations of the superficial branch of the radial nerve and the dorsal branch of the ulnar nerve: A detailed electrophysiological study.

INTRODUCTION: In this study we evaluated anatomic variations of the superficial branch of the radial nerve (SBRN) and the dorsal branch of the ulnar nerve (DBUN) electrophysiologically. METHODS: Antidromic nerve conduction studies (NCS) of the SBRN and DBUN were performed on healthy individuals. To identify individual responses from the distal branches of the SBRN and DBUN, sensory nerve action potentials of each finger (lateral side/medial side) were recorded. RESULTS: NCS were performed in 50 hands of 27 healthy control subjects. The thumb and the index finger were supplied by the SBRN in all cases. The lateral and medial sides of the third finger were supplied by the SBRN in 94.0% and 74.0% of the cases, but the lateral and medial sides of the fourth finger were supplied by the SBRN in only 10.0% and 2.0% of cases. The fifth finger and the medial side of the fourth finger were always supplied by the DBUN. The lateral side of the fourth finger was supplied by the DBUN in 98.0% of cases, but the lateral and medial sides of the third finger were supplied by the DBUN in 40.0% and 70.0% of cases. Dual innervation by the SBRN and DBUN was found in 34.0% and 46.0% of the lateral and medial sides of the third finger, but in only 8.0% and 2.0% of the lateral and medial sides of the fourth finger. DISCUSSION: There are considerable anatomic variations of the SBRN and DBUN in healthy individuals.

Variations in the distal branches of the superficial fibular sensory nerve.

INTRODUCTION: We evaluated anatomic variations of distal branches of the superficial fibular sensory nerve electrophysiologically. METHODS: Orthodromic nerve conduction studies (NCS) of the first and third branches (M-I, M-III) of the medial dorsal cutaneous nerve and the fourth and fifth branches (I-IV, I-V) of the intermediate dorsal cutaneous nerve (IDCN) were performed. To find anomalous innervations from the dorsal sural nerve (DSN) in the IDCN territory, NCS of the fourth and fifth branches (S-IV, S-V) of the DSN were also performed. RESULTS: All sensory nerve action potentials (SNAPs) of M-I and M-III could be obtained bilaterally from 31 healthy Japanese volunteers. SNAPs of I-IV and I-V were recordable in 85.5% and 43.5% of feet, respectively. Anomalous innervations from the DSN were confirmed in 71.0% of S-IV and 93.5% of S-V. CONCLUSION: These results suggest that anatomical variations in the IDCN territory are very frequent in Japanese subjects. Muscle Nerve 55: 74-76, 2017.

Whole plantar nerve conduction study with disposable strip electrodes.

INTRODUCTION: A new method to evaluate whole plantar nerve conduction with disposable strip electrodes (DSEs) is described. METHODS: Whole plantar compound nerve action potentials (CNAPs) were recorded at the ankle. DSEs were attached to the sole for simultaneous stimulation of medial and lateral plantar nerves. We also conducted medial plantar nerve conduction studies using an established method and compared the findings. RESULTS: Whole plantar CNAPs were recorded bilaterally from 32 healthy volunteers. Mean baseline to peak amplitude for CNAPs was 26.9 ± 11.8 µV, and mean maximum conduction velocity was 65.8 ± 8.3 m/s. The mean amplitude of CNAPs obtained by our method was 58.2% higher than that of CNAPs obtained by the Saeed method (26.9 µV vs. 17.0 µV; P < 0.0001). CONCLUSIONS: The higher mean amplitude of whole plantar CNAPs obtained by our method suggests that it enables CNAPs to be obtained easily, even in elderly people.

A novel method to measure sensory nerve conduction of the supraclavicular nerve.

INTRODUCTION: In this report we describe a reliable method for recording sensory nerve action potentials (SNAPs) of the supraclavicular nerve. METHODS: Supraclavicular SNAPs were recorded by placing a surface active electrode at the posterior border of the sternocleidomastoid muscle at a distance of 6 cm from the sternoclavicular joint. The nerve was stimulated at the lower border of the clavicle 4.5 cm lateral to the sternoclavicular joint. RESULTS: Supraclavicular SNAPs were recorded bilaterally from 20 healthy volunteers. Mean onset latency was 1.0 ± 0.2 ms, and mean peak latency was 1.4 ± 0.3 ms. Mean baseline-to-peak amplitude for the SNAPs was 6.1 ± 2.2 µV, and mean maximum conduction velocity was 59.8 ± 6.2 m/s. The mean percentage of side-to-side difference in amplitude was 12.9 ± 11.0%. CONCLUSIONS: Supraclavicular SNAPs could be obtained in all normal subjects. Assessment of supraclavicular nerve conduction is very useful in the diagnosis of supraclavicular neuropathy.

[A case of metronidazole-induced encephalopathy that is difficult to differentiate from Wernicke encephalopathy].

Herein, we present the case of a 76-year-old man diagnosed with an iliopsoas abscess 3 months prior and consequently administered metronidazole. The patient visited our facility complaining of difficulty in speaking and feeling unsteady when walking. Neurological findings showed dysarthria, nystagmus, and bilateral cerebellar ataxia. Head MRI-FLAIR demonstrated symmetrical hyperintensities in the bilateral cerebellar dentate nuclei, red nucleus, periaqueductal of the midbrain, periventricular third ventricle, and the corpus callosum. Although Wernicke's encephalopathy was among the differential diagnoses based on the imaging findings, the thiamine level was normal and improvement in symptoms and hyperintensity on FLAIR within 5 days of discontinuing metronidazole led to the diagnosis of metronidazole-induced encephalopathy. Although there were many similarities in the imaging findings of metronidazole-induced encephalopathy and Wernicke's encephalopathy, Metronidazole-induced encephalopathy should be initially considered when midbrain red nucleus lesions are observed.

Case Report: A Patient With Neuroleptic Malignant Syndrome, Water Intoxication and Hyponatremia Associated With Severe Cerebral Edema and Coma.

Background: Water intoxication is typically caused by primary or psychogenic polydipsia that potentially may lead to fatal disturbance in brain functions. Neuroleptic malignant syndrome (NMS) is a serious complication induced by administration of antipsychotics and other psychotropic drugs. The combination of inappropriate secretion of antidiuretic hormone (SIDAH), NMS and rhabdomyolysis have been rarely reported. Our patient also developed severe water intoxication. Case presentation: Herein we report a comatose case of NMS complicated with water intoxication, syndrome of SIADH and rhabdomyolysis. This patient had severe cerebral edema and hyponatremia that were improved rapidly by the correction of hyponatremia within a couple of days. Conclusions: Malignant neuroleptic syndrome water intoxication, SIADH and rhabdomyolysis can occur simultaneously. Comatose conditions induced by cerebral edema and hyponatremia can be successfully treated by meticulous fluid management and the correction of hyponatremia.

Adult acetonemic vomiting complicated with low body weight in a subject with Mycobacterium avium complex pulmonary disease: a case report.

Pulmonary diseases often cause significant health issues and nutritional disorders. Weight loss and malnutrition are related to the severity of obstructive disorders. Therefore, patients with such conditions often experience low nutritional energy. Acetonemic vomiting is caused by acetonemic syndrome. Previously, it was believe that acetonemic vomiting was observed only in childhood. However, it was recently suggested that acetonemic vomiting can also occur in adults. It is also considered that acetonemic vomiting can occur in subjects with low body weight because stored carbohydrate levels are reduced and fats are mainly used for energy. Consequently, large amounts of acetone are produced, ultimately resulting in nausea and vomiting. In this study, we report a case of adult acetonemic vomiting complicated by low body weight in a subject with Mycobacterium avium complex pulmonary disease.

Origin of far-field potentials in the ulnar compound muscle action potential.

INTRODUCTION: The compound muscle action potential (CMAP) following ulnar nerve stimulation receives a considerable contribution from far-field potentials (FFPs), although their origin is not entirely clear. We investigated this issue using voluntary contractions. METHODS: In 7 control subjects, we placed multiple recording electrodes over the motor points of ulnar-innervated muscles. We asked the subjects to perform a weak movement corresponding to the action of each muscle, and identified the single motor unit potentials (MUPs) from that muscle. We summed the MUPs from each individual muscle and reconstructed the CMAPs. RESULTS: The reconstructed CMAPs coincided well with the actual ones. The N1, P1, and early N2 components of the FFPs were generated primarily by palmar, but also by dorsal, interosseous muscles. The abductor digiti minimi muscle usually generated positive-negative biphasic FFPs, and the negative FFP generated the late N2 component. CONCLUSIONS: These results should prompt a revision of the theory of FFP generation.

[Nonconvulsive Status Epilepticus Associated with Theophylline: A Case Report].

An 87-year-old woman was admitted to our hospital because of speech disturbance and right facio-pharyngo-glosso-masticatory diplegia. She had bronchial asthma, was previously diagnosed with cerebral infarction, had experienced two events of convulsive status epilepticus, and was undergoing treatment with theophylline, levetiracetam, and clopidogrel. Head diffusion-weighted magnetic resonance imaging revealed a high-signal area in the left crus posterior capsula interna. For this, we administered cilostazol along with her regular medicines. On day 14, she had tonic-clonic convulsions, extending from the right upper and lower limbs to the whole body. Subsequently, cilostazol was discontinued, and the dose of levetiracetam was increased. However, she developed severe tonic-clonic seizures with right sensory aphasia and right hemiplegia, for which an increased dose of lacosamide was added. When theophylline was discontinued 5 days after the onset of convulsions, the blood concentration of theophylline was 9.7µg/mL. After theophylline was discontinued, tonic-clonic convulsions improved. The disturbance of consciousness and right hemiparesis were improved after one week, while the disturbance of sensory aphasia was improved after one month. We suspect that cerebral infarction may have aggravated the central nervous system damage caused by theophylline, thereby resulting in aminophylline-related non-convulsive status epilepticus. (Received 20 July 2020; Accepted 27 October 2020; Published 1 March 2021).

Pyogenic psoas abscess on the dorsal side, and bacterial meningitis and spinal epidural abscess on the ventral side, both of which were induced by spontaneous discitis in a patient with diabetes mellitus: A case report.

Type 2 diabetes mellitus patients are immunocompromised, particularly under poorly controlled conditions, and thereby they could develop rare inflammatory diseases, such as spontaneous discitis, pyogenic psoas abscess, spinal epidural abscess and bacterial meningitis. Herein we report a pyogenic psoas abscess on the dorsal side, and bacterial meningitis and spinal epidural abscess on the ventral side, both of which were induced by spontaneous discitis in a patient with poorly controlled type 2 diabetes mellitus. This case was very rare and interesting, because we successfully treated various infections with antibiotics over a long period of time, complicated by hyperglycemic crises, although the patient suffered severe bone destruction and required rehabilitation for a long time.

Intraoperative on-nerve nerve conduction study and conversion factor in the sural nerve.

To determine the conversion factor (CF) of the sural nerve the correlation between the maximum nerve conduction velocity (NCV) and the diameter of the largest fibers was studied in 30 patients suspected of having neuropathy. Sensory nerve action potentials were obtained by on-nerve needle nerve conduction study using needle electrodes placed on the exposed sural nerve during biopsy. The CF was 4.3 (n = 2) in normal sural nerves and close to the normal value (3.85, n = 4) in axonal neuropathy. The CF in demyelinating neuropathy was smaller than the normal value (2.77, n = 24), indicating disproportionately slower conduction than expected from the diameter of nerve fibers. The CF was helpful in differentiating between demyelinating and axonal neuropathies. We propose that a 36% decrease from the mean value of NCV is a reasonable criterion for demyelination of the nerve.

Relationship between the Diabetic Polyneuropathy Index and the Neurological Findings of Diabetic Polyneuropathy.

Objective To achieve an accurate quantification in diabetic polyneuropathy (DPN), we developed a new electrophysiological index that we called the DPN index. The relationship between the DPN index and the neurological findings in diabetic patients was assessed. Methods The DPN index was calculated by the mean value of percentages of four parameters (tibial compound muscle action potential amplitude / F wave minimum latency, sural sensory nerve action potential amplitude / sensory nerve conduction velocity) against the mean normal values. Twenty healthy subjects were recruited as a control group. Patients A total of 348 diabetic patients who were hospitalized in our hospital during the period from December 2016 to August 2019 were retrospectively studied. The correlations between the DPN index and five neurological findings (subjective sensory symptoms, diminished or absent Achilles tendon reflex, impaired tactile and vibration sense, low coefficient of variation of R-R interval) were evaluated. Results The DPN index in healthy subjects was 129.3±32.7%. The DPN index in diabetic patients with one or more neurological findings was significantly lower than that in diabetic patients without any neurological findings (p<0.01: 89.3±27.8% vs. 118.4±21.2%). For each of the five neurological findings, the DPN index in the group with an abnormality was significantly lower than that in the group without any abnormality (each p<0.01). Spearman's correlation coefficients indicated that a greater number of neurological findings resulted in a lower DPN index (r=-0.711, p<0.01). Conclusion Our study suggested that the DPN index is useful for evaluating the severity of DPN.

[A case of Castleman disease accompanying neuropathy only detected by S-SEP in the tibial nerve].

A 77-year-old woman was admitted with a chief complaint of tingling sensation in the both feet, which gradually developed just after the diagnosis of Castleman disease was made. Neurological examination showed mild weakness in the neck and pelvic girdle muscles, and sensory impairment affecting all modalities in the lower legs. Although these neurological findings suggest a diagnosis of neuropathy, nerve conduction studies (NCS) and F-wave disclosed no abnormalities. However, the short latency somatosensory evoked potential (S-SEP) in the tibial nerve revealed a significant delay in the P15 latency, which is indicative of neuropathy affecting proximal potion of the peripheral nerve. To our knowledge, only a few reports described proximal neuropathy associated with Castleman disease. In our case, the examination of S-SEP was very informative to make a diagnosis of neuropathy.

A case of anti-MOG antibody-positive unilaterally dominant meningoencephalitis followed by longitudinally extensive transverse myelitis.

BACKGROUND: There are few reports of anti-myelin oligodendrocyte glycoprotein (MOG) antibody-positive, unilaterally dominant cerebral cortical encephalitis onset with epilepsy. We present such a case in a young female patient with myelitis. CASE PRESENTATION: A 19-year-old female developed generalized tonic seizures lasting several minutes. She had a low-grade fever and headache without other clinical neurological abnormalities while at our hospital. Cerebrospinal fluid (CSF) showed mononuclear pleocytosis. Other laboratory tests indicated no apparent abnormalities. Unilateral meningeal hyperintensity was seen on T2 fluid-attenuated inversion recovery MRI with associated cortical swelling and gadolinium enhancement of the cortical layer. One thousand mg/day of levetiracetam and a 3-day course of intravenous methylprednisolone at 1000 mg/day were administered. Dysuria appeared on the twentieth day of illness, and spinal MRI revealed a longitudinally extensive cord lesion from C5 to L1 consistent with myelitis. Two cycles of a 3-day course of intravenous methylprednisolone at 1000 mg/day were administered, and all symptoms disappeared. We found the patient to be anti-MOG antibody-positive using serum and CSF (titer: serum 1:256; CSF 1:128). CONCLUSION: Our report illustrates a unique case of anti-MOG presenting as new onset epilepsy secondary to unilaterally dominant meningoencephalitis preceding the onset of longitudinally extensive transverse myelitis.

Influence of placement sites of the active recording electrode on CMAP configuration in the trapezius muscle.

OBJECTIVE: We investigated how the active electrode placement site influences compound muscle action potential (CMAP) configuration of the upper trapezius muscle (TM). METHODS: A nerve conduction study of the accessory nerve was performed, and the CMAPs obtained with two different placement sites, i.e., placement of the active recording electrode on the belly of the upper TM (CMAP-A) and placement of the electrode 2 cm behind the belly (CMAP-B), were compared. CMAPs were also obtained with the active recording electrode placed in the supraspinous fossa (CMAP-C). RESULTS: All CMAPs were recorded from 21 healthy volunteers. The mean peak-to-peak amplitude of CMAP-B was 3.4 mV higher than that of CMAP-A (11.0 ±â€¯4.0 mV vs. 14.4 ±â€¯4.9 mV; P < 0.01). The mean peak-to-peak amplitude of CMAP-C was 10.3 ±â€¯5.0 mV. CONCLUSIONS: CMAP of the upper TM was always higher when the active recording electrode was placed 2 cm behind the belly of the muscle. SIGNIFICANCE: When stimulating the accessory nerve, a current spread occurs to the C5 spinal nerve root and another CMAP originating from the supraspinatus muscle occurs in the supraspinous fossa. The volume conduction from the supraspinatus muscle affects the active recording electrode on the TM, resulting in an increase in CMAP amplitude.

Abnormal dip phenomenon: a characteristic electrophysiological marker in interdigital neuropathy of the foot.

OBJECTIVE: The nerve conduction findings in interdigital neuropathy of the foot (IDN; Morton's neuroma) have rarely been reported. We analyzed the nerve conduction data in 23 patients with suspected IDN studied between 1982 and 2002. METHOD: Diagnosis of IDN was made on the basis of clinical features. All patients underwent routine nerve conduction studies and a near-nerve needle sensory nerve conduction study of the interdigital nerves by Oh's method in the symptomatic foot. RESULTS: Of the 23 patients, the diagnosis of definite IDN was made in 13 cases and of possible NDN in the others cases. Nineteen were females. Twenty two patients had only one nerve affected. One patient had two nerves affected. The III-IV interdigital nerve was affected in 17 cases and the II-III interdigital nerve in 7 cases. The near-nerve needle nerve conduction showed abnormality in the affected interdigital nerves in all definite IDN cases and confirmed the diagnosis of IDN in 10 cases by the abnormal dip phenomenon (a selective decrease of 50% or more in the sensory CNAP amplitude of the affected nerve compared with that of the preceding interdigital nerve). In 11 possible IDN cases, IDN was identified by the abnormal dip phenomenon. CONCLUSION: The near-nerve needle sensory nerve conduction of the interdigital nerves is a highly sensitive diagnostic test, and abnormal dip phenomenon is the most characteristic electrophysiological marker for the diagnosis of IDN.

A new technique for dorsal sural nerve conduction study with surface strip electrodes.

OBJECTIVE: To obtain higher amplitude of dorsal sural sensory nerve action potentials (SNAPs), we used a new method for dorsal sural nerve conduction study with surface strip electrodes (SSEs). METHODS: Dorsal sural SNAPs were recorded orthodromically. The recording electrodes were placed behind the lateral malleolus. SSEs were attached to the laterodorsal aspect of the foot for stimulation of the dorsal sural nerve (DSN). We also used a conventional method with a standard bipolar stimulator and compared the findings. RESULTS: Dorsal sural SNAPs were recordable bilaterally from 49 healthy volunteers. Mean peak-to-peak amplitude for SNAPs was 12.9±6.3µV, and mean nerve conduction velocity was 44.8±5.5m/s. The mean amplitude of SNAPs obtained by our method was 118.6% higher than that of SNAPs obtained by the conventional method (12.9µVvs. 5.9µV; P<0.001). CONCLUSIONS: The highest amplitude of dorsal sural SNAPs was constantly obtained by SSEs since SNAPs arising from whole digital branches of the DSN could be elicited by placement of SSEs. SIGNIFICANCE: When the DSN supplies more cutaneous branches to the lateral half of the foot, SSEs gives higher amplitude of dorsal sural SNAPs than that of the standard innervation type.