Normal Sensory Nerve Action Potentials Research Articles

Phenotypic variability in TRPV4-associated neuropathies and neuronopathies: a case series

TRPV4‑associated neuromuscular diseases represent a clinical spectrum of neuropathies and motor neuron disorders. To date, 3 phenotypic forms are distinguished. There are Charcot–Marie–Tooth disease type 2C, distal hereditary motor neuropathy type 8 (DHMN8), scapulo‑peroneal spinal muscular atrophy (SPSMA). Here we report 3 families with DNMN8 and one family with SPSMA. In all cases, DNA‑analysis revealed single nucleotide variants in the TRPV4 gene previously reported as pathogenic. In 3 probands, a combination of signs of both motor and motor‑sensory neuropathies led to difficulties in the establishment of the clinical diagnosis. Patients had mild sensory disturbances in the feet, but in all of these cases nerve conduction study revealed normal sensory nerve action potentials. Considering the prevailing signs of motor neuropathy, these patients were diagnosed with DNMN8. Clinical signs of sensory disturbances are regarded as not contradicting the diagnosis, since they can be observed in various forms of distal motor neuropathies. The clinical features of SPSMA in one patient corresponded to those previously described in the literature. The involvement of the shoulder girdle muscles and the peroneal muscles and neurogenic changes in needle electromyography allow suspecting SPSMA clinically. A distinctive features of TRPV4‑associated neuromuscular diseases are the vocal cords paresis, sensorineural hearing loss and respiratory failure, however they are not obligatory according to our clinical reports.

SARS-CoV-2 parainfection associated Landry -Guillain- Barre Syndrome (LGBS) in a term pregnant women: A clinical conundrum.

Sir Guillain-Barre Syndrome (GBS) is a rare neurological disease that is characterized by progressive weakness in legs and arms, areflexia, or decreased tendon reflexes in weak limbs.[1] Evidence of GBS cases associated with SARS-CoV-2 infection has recently been reported.[2] Though GBS is considered mostly a post-infectious, immune-mediated disease, it might also occur during the infectious phase in some cases. Herein, we report first case of SARS-CoV-2 parainfection associated GBS in a term pregnant patient. A 22 year primigravida at 36 weeks of gestation, presented with acute onset of quadriparesis since 3 days and cough since 2 days. Patient c/o weakness in all four limbs, sudden onset, started distally in both lower limbs which progressed to involve upper limbs. On examination, she was tachypneic with respiratory rate of 32-34 breaths/min. She maintained saturation of 97% on ventimask at 0.4 fraction of inspired oxygen. On motor examination, in lower limb she had power of 2/5 at both ankle and knee joints. At hip joint, she had power of 1/5. In upper limb, she had power of 3/5 at both the shoulders and 4/5 at both the elbow joints. Deep tendon reflexes were absent. Her blood investigations were normal except for total serum bilirubin which was 3.2 mg/dl. She also tested SARS CoV-2 reverse transcriptase positive. Since she had no prior history of any gastrointestinal infection, she was diagnosed as SARS-CoV-2 parainfection associated Landry -Guillain- Barre Syndrome (LGBS) with respiratory involvement. In view of the worsening motor weakness and decline in respiratory functions, she was planned for urgent caesarean section. After preoxygenation, rapid sequence induction was done using thiopentone sodium and rocuronium and intubated with oral cuffed endotracheal tube with 7.0 mm internal diameter. She was ventilated using controlled mode with peak inspiratory pressure of 22 cm water, positive end expiratory pressure 5 and maintained on sevoflurane + oxygen at minimum alveolar concentration of 0.7-1. After delivery of baby, oxytocine infusion was started at 5 IU/h and injection fentanyl 50 μg was administered. Post-surgery she was shifted unreversed to COVID-19 intensive care unit (ICU). In ICU, she was administered intravenous immunoglobulins gram once a day (OD) for 4 days, low molecular weight heparin 0.6 ml OD, injection dexamethasone 6 mg twice a day, and Tablet Gabapentin 300 mg at night. Her CSF analysis showed total protein of 31.5 mg/dl and glucose levels of 68.9 mg/dL. During her ICU stay, she developed collapse and consolidation of left lung lower lobe with left sided pleural effusion, which resolved over next few days after she was tracheostomized. After 10 days of her ICU stay, she tested SARS-CoV-2 reverse transcriptase negative. Thereafter, she was shifted to non-COVID-19 ICU where she was gradually weaned from ventilatory support. Her nerve conduction study was performed which reported complete absence of compound muscle action potential (CAMP) with normal sensory nerve action potential (SNAP) suggestive of Acute Motor Axonal Polyneuropathy (AMAN) [Table 1]. She was shifted to medical ward for rehabilitative care. She was discharged from the hospital and was mobilized using wheel chair. There was complete return of motor power in upper limbs.Table 1: Nerve conduction study parameters of the patientTo the best of our knowledge, this is the first reported case of SARS-CoV-2 parainfection associated LGBS in term pregnant patient. She presented with short history of acute onset of muscle weakness accompanied by cough which gradually worsened and required assisted ventilation. As patient had already reached term, emergent caesarean section followed by management according to SARS-CoV-2 protocols was done. Guillain barre syndrome (GBS) worsens in postpartum period due to restoration of cellular immunity, with increase in delayed type of hypersensitivity which was adaptively depressed during pregnancy.[3] In an observational multicentre study, thirty GBS cases associated with COVID-19, stated COVID-19-associated GBS as being predominantly demyelinating and more severe than non-COVID-19 GBS.[4] Tekin et al.[5] have reported occurrence of LGBS in pregnant patient who had preceding SARS-CoV-2 infection. The patient developed muscle weakness in postpartum period, which recovered after receiving intravenous immunoglobulins. The prognosis of SARS-CoV-2 parainfection associated LGBS in term pregnant patient is still unclear and requires early recognition of danger signs for timely management and favorable outcome. Thus, clinical course of SARS-CoV-2 parainfection associated LGBS during pregnancy is highly complicated, due to presence of non-specific signs and symptoms and carries high risk of maternal morbidity. Early identification and multidisciplinary involvement are essential for diagnosis and good outcome. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Small-fibre Neuropathy in Patients with Familial Amyotrophic Lateral Sclerosis Type 8.

Amyotrophic lateral sclerosis (ALS) is a degenerative disease of the nervous system that primarily affects motor neurons. ALS type 8 (ALS8) is a familiar form with predominant involvement of lower motor neurons, tremor, and slow progression. The aim of this study was to describe sensory involvement in a cohort of ALS8 patients and compare it with the characteristics of sporadic ALS (sALS) patients and controls. We compared data from 40 ALS8 and 10 sALS patients assessed by neurological evaluation and electrophysiological study. Skin biopsies were performed in these patients and 12 controls for analysis of intraepidermal nerve fiber (IENF) density by protein gene product 9.5 (PGP 9.5) immunohistochemistry. The ALS8 group was younger than the sALS group at the onset of symptoms (p < 0.05) and had a longer disease evolution (p < 0.01). Sensory abnormalities were evident in 35% of the ALS8 and 30% of the sALS patients by neurological examination, and all ALS patients presented normal sensory nerve action potentials. Despite being similar in the ALS8 and sALS groups, IENF density in the ALS8 group was lower than that in the controls (p < 0.0005). In the ALS8 group, IENF density was significantly lower in patients with impairment of vibratory sensation than in those without this finding (p < 0.05) and in females than in males (p < 0.05). Sensory impairment and decreased IENF density are present in ALS8 patients at a frequency and intensity similar to that in the sALS group.

LBODP037 Acute Foot Drop In An Adolescent With Type 1 Diabetes Mellitus At Onset: A Case Report

Abstract Background The incidence of type 1 diabetes (T1D) among youth is on the rise worldwide. Diabetic neuropathy is often a late manifestation of diabetes and usually results from the exposure to prolonged hyperglycemia, oxidative and inflammatory stress, and dyslipidemia. Here, we report a case of painless diabetic mononeuropathy as the presenting symptom of T1D that improved shortly after the improvement in glycemic control. Clinical case A previously healthy 15-year-old boy, presented to the emergency department (ED) with left foot weakness and dragging for 1 week. This was preceded by numbness over the left lateral leg and dorsum of the left foot. There was no history of trauma. The patient reported a history of polyuria, polydipsia, and significant weight loss for 3 months, for which he did not seek medical care. There was no family history of diabetes, hereditary neuropathy, or autoimmune diseases. Upon presentation to the ED, a general physical examination was unremarkable with a weight of 60 Kg (BMI= 20 Kg/m2), neurological examination revealed weakness in the dorsiflexion of the left foot (3/5), eversion (4/5), and normal sensation and reflexes. The remainder of the neurological examination including the right foot, upper extremities, cerebellar functions, cranial nerves and monofilament and vibration sensory testing was normal. Fundoscopic exam showed no evidence of retinopathy. The initial laboratory investigations revealed mild DKA (PH 7.28, HCO3 16mmol/L, Na 137 mEq/L, random blood glucose of 306 mg/dl, positive blood ketones) and normal kidney function. A nerve conduction study showed moderate left peroneal motor axonal neuropathy, with normal sensory nerve action potentials. Brain CT scan was unremarkable. Further tests to rule out secondary causes of neuropathy (ANA, B12 level, and thyroid function) were within normal. The diagnosis of diabetes-related mononeuropathy was confirmed by the neurology team and the patient underwent physiotherapy. After the resolution of DKA, the patient continued to use basal/bolus insulin therapy and was discharged home with close follow-up of blood glucose readings. His glycemic control has improved, and the patient reported a significant improvement in the foot drop 3 weeks later. A repeated examination by the neurology team 3 months later confirmed a complete recovery of the left foot drop. Conclusion Acute diabetic mononeuropathy can be an unusual presenting feature of T1D and may pose a diagnostic challenge. Although diabetic mononeuropathy is often a late complication of diabetes, our patient presented with acute mononeuropathy at the onset of T1D. This case highlights the importance of early diagnosis and management of diabetes to prevent and sometimes reverse diabetic neuropathy. It also shows that a complete recovery of acute diabetic mononeuropathy can be achieved by improving glycemic control in patients with newly diagnosed T1D. Presentation: No date and time listed

Vibratory testing with the 64 Hz Rydel-Seiffer tuning fork and its relation to the sural nerve action potential.

Despite its widespread use, little is known regarding the ability of the semi-quantitative Rydel-Seiffer tuning fork to designate peripheral nerve function. We sought to determine in a large sample of normal and abnormal nerves the relationship between vibration sense and compound sensory nerve action potential (SNAP) parameters recorded in a corresponding innervation area. Vibratory thresholds were determined on a scale of 0 to 8 with a 64 Hz Rydel-Seiffer tuning fork placed on the lateral malleolus of 303 subjects. Sural nerve sensory neurography was employed to derive SNAP parameters, which were related to vibration sense by means of multiple linear regression. ROC curve analysis was performed to determine the classification efficacy of the tuning fork in distinguishing normal from abnormal sural nerve responses. SNAP amplitude was the most significant predictor in the whole subjects group and in the subgroup of subjects with normal SNAPs, whereas conduction velocity played a major role in subjects with abnormal SNAPs. Age was significantly associated with vibration perception, particularly in subjects with normal SNAPs. With an area under the curve of 0.730, vibration sense was a fair classifier for decreased SNAP amplitudes. The optimal vibratory cutoff was 4.2. Age is a major determinant of vibratory test results, highlighting the importance of aging of central and peripheral pathways in mediating vibration sense. Hence, neurophysiological testing cannot be omitted in the context of polyneuropathy work-up, since even at the optimal cutoff threshold, vibratory examination still displays 40% false negative test results.

Isolated acute bilateral ophthalmoplegia as a form of anti-GQ1b syndrome - a case report and differential diagnostic considerations

WCN 2013 No: 1101 Topic: 7 — Neuromuscular disorders Isolated acute bilateral ophthalmoplegia as a form of anti-GQ1b syndrome a case report and differential diagnostic considerations A. Toth, G. Aradi, I. Vastagh, K. Pozsegovits, L. Rencz, D. Bereczki, Z. Aranyi. Department of Neurology, Semmelweis University, Faculty of Medicine, Budapest, Hungary; Department of Neurology, Dr. Kenessey Albert Hospital, Balassagyarmat, Hungary Background: Isolated acute bilateral ophthalmoplegia is an uncommon occurrence, but it may cause differential diagnostic problems. It may be a manifestation of the Miller Fisher syndrome spectrum, which has been recently referred to as anti-GQ1b syndrome. Objective: To present a case with acute bilateral ophthalmoplegia associated with anti-GQ1b antibody positivity, but without other typical signs of Miller Fisher syndrome (MFS). Differential diagnostic aspects are highlighted. Patient: A 57-year-old female patient presented with an acute onset of diplopia, progressing to bilateral ophthalmoplegia within days. These symptoms were preceded by flu-like symptoms. Deep tendon reflexes were diminished, otherwise her neurological status was unremarkable, the typical triad of MFSwas not observed. MRI of the brain was normal. Cerebrospinal fluid examination revealed increased protein content with normal cell count. Electrophysiological assessment showed normal sensory nerve action potentials, whereas low amplitude or absent sensory nerve action potentials are characteristic findings in MFS. Serological testing confirmed anti-GQ1b class IgG antibody positivity, supporting the diagnosis of MFS spectrum. The patient fully recovered within 3 months, without any specific treatment, showing the benign nature of the condition. Discussion: Acute ophthalmoparesis may be a restricted form antiGQ1b syndrome. In addition to classical MFS, further variants include Bickerstaff's brainstem encephalitis, pharyngeal-cervical-brachial paresis, and acute ataxic sensory neuropathy. Although acute ophthalmoparesis as a manifestation of anti-GQ1b syndrome is a benign condition, it may cause differential diagnostic problems with potentially more serious conditions needing prompt treatment, such as Wernicke's encephalopathy, ocularmyasthenia, botulism, paraneoplastic brainstemencephalitis, or brainstem stroke. doi:10.1016/j.jns.2013.07.1569 Abstract — WCN 2013 No: 1413 Topic: 7 — Neuromuscular disorders “Reporting biomarker” development: Update in als patients treated with G-CSF -mobilized hematopoietic stem cells WCN 2013 No: 1413 Topic: 7 — Neuromuscular disorders “Reporting biomarker” development: Update in als patients treated with G-CSF -mobilized hematopoietic stem cells A.V. Khomenko, D. Baldaranov, J. Grassinger, S.W. Johannesen, I. Kobor, J. Roesl, K. Kollewe, S. Petri, R. Dengler, M. Deppe, A. Ludolph, J. Kassubek, G. Schuierer, T. Bruun, W. Schulte-Mattler, U. Bogdahn. Department of Neurology, University of Regensburg, Regensburg, Germany; Department of Haematology and Internal Oncology, University Hospital Regensburg, Regensburg, Germany; Clinic for Neurology, Medizinische Hochschule Hannover, Hannover, Germany; Department of Neurology, University of Muenster, Muenster, Germany; Neurological University Clinic, University Ulm, Ulm, Germany; Department of Neuroradiology, University of Regensburg,

Sensory chronic inflammatory demyelinating polyneuropathy: An under-recognized entity?

Sensory chronic inflammatory demyelinating polyneuropathy (CIDP) can be difficult to diagnose. We report 22 patients with chronic sensory polyneuropathy with ≥1 clinical sign atypical for chronic idiopathic axonal polyneuropathy (CIAP) but no electrodiagnostic criteria for CIDP. Clinical signs atypical for CIAP were: sensory ataxia (59%), generalized areflexia (36%), cranial nerve involvement (32%), rapid upper limb involvement (40%), and age at onset ≤55 years (50%). Additional features were: normal sensory nerve action potentials (36%), abnormal radial/normal sural pattern (23%), abnormal somatosensory evoked potentials (SSEPs) (100%), elevated cerebrospinal fluid (CSF) protein (73%), and demyelinating features in 5/7 nerve biopsies. Over 90% of patients responded to immunotherapy. We conclude that all patients had sensory CIDP. Sensory CIDP patients can be misdiagnosed as having CIAP. If atypical clinical/electrophysiologic features are present, we recommend performing SSEPs and CSF examination. Nerve biopsy should be restricted to disabled patients if other examinations are inconclusive.

Miopatía del enfermo crítico. Valoración neurofisiológica y biopsia muscular en 33 pacientes

Critical illness patients may show marked weakness acquired in the Intensive Care Unit (ICU). There are some disagreements about the myopathic versus neuropathic damage in this condition, presumably due to the lack of reliable diagnostic criteria. To report the neurophysiological findings in critical patients, to classify them in groups according to the electro-physiological data of myopathy, and to ascertain the rapport between the neurophysiological classification of myopathy and the muscle biopsy results. A prospective assessment of 33 ICU patients with marked weakness by means of needle electro-myography, electroneurography, and percutaneous muscle biopsy was carried out. Direct muscle stimulation was performed in 9 patients and repetitive nerve stimulation in 14 cases. RESULTS. According to neurophysiological criteria, patients were classified in 3 groups: definite (33%), probable (46%), and uncertain (21%) myopathy. The most conspicuous myopathic pathological findings including fibrillar atrophy and necrosis, vacuoles, and myosin and mitochondrial anomalies, were observed in both, definite and probable groups (26 patients). In 17 of these cases, low amplitude of the compound motor action potentials and normal sensory nerve action potentials were found. Axonal sensory-motor neuropathy was present in 11 patients, concomitant with neurophysiological data of myopathy in 7 cases. Based on the neurophysiological criteria for the assessment and classification of acquired weakness in critically ill patients, myopathy is highly predominant over the neuropathic impairment. Histopathological findings are closely related to the electrophysiological diagnosis of myopathy. Neither neurophysiological nor pathological data support a hypothetic motor axonal neuropathy in this series.

Diagnostic pitfall: wound botulism in an intoxicated intravenous drug abuser presenting with respiratory failure

Sir: Wound botulism has gained importance because of rising occurrence among injecting drug users (IDUs) in the United Kingdom and United States over the past 20 years [1–3] and recently also in Germany [4]. The causative organism is Clostridium botulinum, an anaerobic, gram-positive, spore-forming bacterium. We report a case of wound botulism initially misdiagnosed as drug intoxication. A 30-year-old female IDU was admitted to the emergency department because of rapidly progressing dyspnea. She was intubated and transferred to the medical ICU. Toxicological screening revealed an intake of flunitrazepam, methadone, and cocaine, and the initial diagnosis was respiratory failure due to intoxication. A formal neurological examination of the patient, who was still ventilated on day 3, revealed high-grade flaccid tetraparesis, facial diplegia, and bilateral ptosis. Pupils were dilated and did not react to light. Eye movements were conjugate with slowed saccades and vertical gaze paralysis. There was generalized areflexia with negative Babinski signs and no sensory deficits. Nonverbal communication (via discrete hand squeezing and minimal head movements) was normal. There were multiple scarred syringe abscesses at both legs, and one smaller florid abscess in the right groin. Nerve conduction studies revealed strongly reduced motor action potential amplitudes with normal sensory nerve action potentials. Repetitive stimulation of several peripheral nerves showed no decrement or increment. Cerebrospinal fluid examinations on days 3, 6, and 28 revealed normal cell counts, protein and lactate levels. The clinical syndrome of mydriasis, cranial nerve palsies, and flaccid tetraparesis led to the diagnosis of wound botulism. The diagnosis was confirmed on day 6 after admission by a positive mouse bioassay, which revealed subtype botulinum toxin A. The patient was treated with polyvalent antitoxin and penicillin G. The florid abscess in the groin was incised and drained. C. botulinum could not be cultured in the abscess tissue. The patient needed ventilatory support and intensive care for 3 months. She was then transferred to a rehabilitation clinic where she slowly recovered motor functions. After 6 months she was able to walk again without assistance and was discharged into ambulatory care. Wound botulism is caused by the toxin of C. botulinum which presynaptically blocks the release of acetylcholine from cholinergic nerves, predominantly at the neuromuscular junction. The anaerobic environment of a syringe abscess together with the tissue damage caused by citric acid (commonly used as solvent by IDUs) is considered to favor wound botulism [1]. Clinical features involve dyspnea, dysphonia, mydriasis, diplopia, dysphagia, and descending paralysis [5]. Mouse bioassay studies and/or isolation of C. botulinum from wound cultures are required for diagnosis. The diagnostic pitfall in our case was the presence of high blood levels of a benzodiazepine (which causes slow saccades), methadone, and cocaine (which causes mydriasis), resulting in delayed diagnosis and treatment. Wound botulism should be considered in IDUs presenting with respiratory failure. Even in the presence of alternative causes of respiratory insufficiency clinicians should have a high index of suspicion for wound botulism in IDUs.

Validation of an Electromyography and Nerve Conduction Study Protocol for the Analysis of Brachial Plexus Lesions in 184 Consecutive Patients With Traumatic Lesions

To validate a concentric needle electromyography (EMG) and nerve conduction study (NCS) protocol for the preoperative analysis of brachial plexus lesions.METHODS. 184 consecutive patients with traumatic brachial plexus lesions were analyzed. The results of the neurophysiological studies were compared with the final diagnoses based on the results of computed tomography-myelography and findings during the operation. The protocol proved reliable in the analysis of these lesions in 84% of cases. Limitations were that extraforaminal lesions may mask root avulsion or central lesions; paraspinal sampling is of limited value in multiple root lesions because of the overlap in innervation; and sometimes normal sensory nerve action potentials (SNAPs) could occur in an extra foraminal lesion. Lesions outside the plexus were found in 21% of the patients, most of which would not have been expected on clinical grounds. With this protocol, a reliable analysis of traumatic brachial plexus lesions can be made in 84% of the patients, even finding lesions outside the brachial plexus not expected on clinical grounds in 2l degrees of the patients.

A novel form of distal hereditary motor neuronopathy maps to chromosome 9p21.1–p12

Distal hereditary motor neuronopathies (dHMNs) form a heterogeneous group of rare disorders characterized by distal weakness and wasting in the limbs with no significant sensory involvement. Harding has classified dHMNs into seven categories based on clinical and genetic criteria. We report a novel form of autosomal recessive dHMN in 7 consanguineous families located in the Jerash region of Jordan. Onset of the disease is between 6 and 10 years of age and is characterized by weakness and atrophy of the lower limbs associated with pyramidal features. Within 2 years, symptoms progress to the upper limbs. Neurophysiological studies typically show normal conduction velocities, reduced compound motor action potential amplitudes, normal sensory nerve action potentials, and chronic neurogenic changes on needle electromyography. No significant abnormalities are seen on sural nerve biopsy. We call this novel form of dHMN Jerash hereditary motor neuronopathy. We studied the families at the molecular genetic level and mapped the Jerash hereditary motor neuronopathy gene to an approximately 0.54-cM region on chromosome 9p21.1-p12, flanked by microsatellite polymorphic marker loci D9S1845 and D9S1791. A maximum LOD score of 19.80 at theta = 0.001 was obtained between the disease and locus D9S1878.

手指のしびれと環指の知覚神経活動電位

Median and ulnar sensory nerve conduction velocities and amplitudes were measured orthodromically on the ring finger in 10 normal hands and in 64 hands with numbness (31 hands with carpal tunnel syndrome (CTS), 16 hands with cubital tunnel syndrome (CubTS), 8 hands with paresthesia due to cervical spondylosis (CS) and 9 hands with diabetic neuropathy (DN)). Of 31 hands with CTS, 13 hands had slow conduction velocities (35.6±7.3m/s) and 18 hands had no sensory nerve action potential (SNAP) in the median nerve. Of 16 hands with CubTS, 12 hands had no SNAP and 4 had normal ulnar nerve conduction velocities. Nine hands with DN had low amplitudes and slow conduction velocities in both nerves. Eight hands with CS had normal SNAPs in both nerves. We concluded that measurement of SNAP of the ring finger is easy and useful for diagnosing numbness in hands.

NOT ‘INDIFFERENCE TO PAIN’ BUT VARIETIES OF HEREDITARY SENSORY AND AUTONOMIC NEUROPATHY

Three children, from different kinships, with generalized insensitivity to pain, showed unusual manifestations of congenital, presumably inherited, sensory and autonomic neuropathy. The first child appeared to have a syndrome resembling those previously described as congenital indifference to pain, congenital universal loss of pain sensation from infancy without other apparent neurological deficit. Unlike most types of hereditary sensory and autonomic neuropathies (types I, II, III), but like type IV, she had normal sensory nerve action potentials. Abnormalities of sudomotor function and of somatosensory evoked potentials were demonstrated. A severe decrease in the number of sural nerve A delta fibres and a small reduction in C fibres were demonstrated morphometrically. An abnormality of C fibres was confirmed by a marked reduction in nerve dopamine-beta-hydroxylase activity. The plasma and CSF concentrations of beta endorphins, substance P and several other neuropeptides and hormones were normal. Unequivocal evidence of a neuropathic lesion is provided by this patient; her disorder may be identified as the fifth type of hereditary sensory and autonomic neuropathy. The second patient had a congenital pansensory neuropathy and progressive retinitis pigmentosa. Whether the disorder is inherited and, if so, whether the retinitis pigmentosa results from the same or from a second genetic abnormality, is unclear. The third case has, in addition to what is usually seen in hereditary sensory and autonomic neuropathy, type II, an unusually severe kinaesthetic difficulty in oral food handling. The sural nerves of the second and third patients had fibre composition characteristic of hereditary sensory and autonomic neuropathy, type II, few or no myelinated fibres and reduced numbers of unmyelinated fibres.

Temperature dependence of normal sensory nerve action potentials.

Sensory conduction velocities of normal subjects are increasing linearly with rising temperature. The duration of the compound sensory action potentials recorded from the median nerve at the wrist and elbow shows a negative temperature coefficient. The peak-to-peak amplitude of these potentials increases from 22 degrees to approximately 26 degrees C and then decreases progressively again up to 36 degrees C. It is believed that this behavior is due to a combination of decreasing temporal dispersion, height and duration of the individual spike potentials.