Ken Johkura

Central Paroxysmal Positional Vertigo: Isolated Dizziness Caused by Small Cerebellar Hemorrhage

To the Editor: Kerber et al1 report that the proportion of cerebrovascular events in patients presenting to the emergency department with dizziness, vertigo, or imbalance is very low (3.2%), and when these symptoms are not accompanied by any other neurological signs or symptoms, stroke/transient ischemic attack is diagnosed in only 0.7% of patients. They conclude that dizziness, vertigo, and/or imbalance in isolation is a strong indicator of a noncerebrovascular cause. We agree with their conclusion. However, there is a potentially serious pitfall. We reported the diagnoses in consecutive patients presenting to the emergency department of our hospital between April 2002 and …

Defective auditory recognition after small hemorrhage in the inferior colliculi

We report the case of a male patient with a traumatic small hemorrhage partially involving the bilateral inferior colliculi without evidence of a temporal lobe lesion. He was unable to comprehend spoken words although he had intact speech production, reading and writing abilities. Comprehension of environmental sounds was also affected. Among the receptive musical abilities, discrimination of intensity, tone and rhythm were preserved, while recognition of melody was impaired. Audiometry showed normal thresholds for pure tone. Waves I-IV of brainstem auditory evoked potentials were elicited normally, whereas the wave V was elicited with reduced amplitude and prolonged latencies on both sides. The main component of middle latency auditory evoked potentials, which is evoked over both hemispheres by monaural stimulation to either side in normal subjects, was elicited only over the hemisphere contralateral to the ear receiving stimulation. Our patients auditory findings were similar to those usually found in generalized auditory agnosia. Auditory agnosia is usually considered as a sign of a bitemporal cortical or subcortical disorder, but, in our patient, a brainstem disorder caused a disturbance of auditory recognition similar to auditory agnosia due to a bitemporal lesion. Our patients auditory findings may belong to the category of a brainstem auditory-processing disorder brought on by a small hemorrhage in the inferior colliculi. In addition, the impairment in our patient implies that, in the neural processing of musical parameters, the decoding of intensity, tone and rhythm is accomplished at the level of inferior colliculus, whereas further cortical processing is necessary for the appropriate recognition of melody.

Rapid resolution of nerve conduction blocks after plasmapheresis in Guillain-Barré syndrome associated with anti-GM1b IgG antibody.

Sirs: Anti-ganglioside antibodies are common during the acute phase of the illness in sera from patients with Guillain-Barré syndrome (GBS). IgG antibody against a minor monosialoganglioside GM1b is recognized as a useful diagnostic marker of GBS [8, 14], but its pathogenetic role has yet to be clarified. Few reports have provided electrophysiological findings on IgG anti-GM1b positive GBS [8, 14, 15, 16]. We previously reported (in Japanese) a patient with GBS who developed rapidly reversible nerve conduction blocks at multiple common compression sites, indicating the vulnerability of these sites [12]. Further serological evaluation has shown the presence of anti-GM1b IgG antibody. We here describe the clinical course of the disease and the detailed electrophysiological or serological findings. A previously healthy 22-year-old man with a 2-week history of progressive weakness and paraesthesia of all four limbs was referred to our hospital. He had had slight fever and diarrhoea 2 weeks before the onset of neurological symptoms. On admission he showed flaccid tetraparesis with symmetrical weakness in the distal limbs (Medical Research Council grade 2–3), hypoactive ankle jerk, positive Lasègue sign on both sides, but no apparent sensory signs. He could walk more than 5 m without assistance. The cerebrospinal fluid had elevated protein of 88 mg/dl with normal cellularity. GBS was diagnosed, and he twice underwent plasmapheresis (days 14 and 19). Weakness and paraesthesia disappeared within 2 weeks after treatment. He was discharged from the hospital on day 30 with no residual symptoms. Electrophysiological assessment on admission (day 13) showed nerve conduction blocks across the elbow segments in the ulnar nerves and across the fibular heads in the peroneal nerves on both sides (Fig. 1, Table 1). The nerves were carefully stimulated using supramaximal intensity to prevent the false impression of conduction LETTER TO THE EDITORS

Positional nystagmus in patients with chronic dizziness

Background: In elderly people, chronic dizziness is endemic. However, chronic dizziness of unknown origin is difficult to assess. Objective: To investigate whether mild unrecognised benign paroxysmal positional vertigo (BPPV) is a cause of isolated chronic dizziness in the elderly. Patients and methods: The prevalence of extremely weak, horizontal, direction changing apogeotropic positional nystagmus (HAPN) that had not been detected by conventional examination was evaluated in 200 patients with isolated chronic dizziness and in 155 age matched control subjects without dizziness. Results: A high prevalence of weak HAPN was found in patients with isolated chronic dizziness (98/200 (49.0%)) compared with the prevalence in control subjects without dizziness (25/155 (16.1%); p<0.0001). Symptoms improved in some patients by daily positional exercise for BPPV. Conclusion: Because BPPV is the most common cause of dizziness in the elderly, and HAPN is a characteristic of horizontal canal BPPV, our findings suggest that mild persistent BPPV is a possible cause of chronic dizziness of otherwise unknown origin in the elderly.

Thalamic involvement of Epstein-Barr virus encephalitis demonstrated by MRI

Sirs: Epstein-Barr virus (EBV), recognized as the cause of infectious mononucleosis, can lead to encephalitis as a neurological complication. Although imaging studies are normal in the majority of patients with EBV encephalitis, basal ganglia or brainstem lesions are detected in some cases [1, 2]. Thalamic lesions, however, are rarely reported in cases of EBV encephalitis. Thalamic lesions detected by MRI are generally thought to be characteristic of Japanese encephalitis [4], and they, sometimes associated with basal ganglia lesions, are seen in most Japanese encephalitis patients [4]. Herein, we describe a patient with EBV encephalitis in whom MRI showed bilateral thalamic lesions in addition to basal ganglia lesions, mimicking Japanese encephalitis. A previously healthy 52-year-old man was hospitalized for decreased alertness. Over the next few days, his condition deteriorated, and he was referred to our hospital. The patient was comatose upon examination, and stiff neck was noted. His temperature was high at around 39 °C. The results of routine blood and urine tests were normal, and blood chemistry indicated normal liver function without ammonia elevation. The blood concentration of vitamin B1 was normal. Cerebrospinal fluid (CSF) examination revealed pleocytosis (174/mm3, mainly mononuclear cells) and elevated total protein (150 mg/dL) with normal glucose. CSF and blood concentrations of lactate and pyruvate were normal. Although the result of brain CT on admission was normal, brain CT and MRI 3 days after admission revealed bilateral lesions involving basal ganglia and the thalamus (Fig. 1A). Electroencephalography showed a generalized slow alpha rhythm of 8–9 Hz, but the slow alpha activity showed no response to painful stimuli, suggesting alpha coma. Bacterial and fungal CSF cultures were negative. Serologic studies revealed elevated anti-Epstein-Barr virus-induced early antigens (EA-D and EA-R) antibody together with a twofold increase of anti-Epstein-Barr viral capsid antigen antibody (VCA-IgG) titers in paired serum. EA antibody did not decrease during the month after admission. Serial polymerase chain reaction (PCR) analysis of CSF was positive for EBV on hospital days 1, 7, and 14 and negative on hospital days 21 and 28. Serological tests for other viruses including herpes simplex virus, varicellazoster virus, human herpes virus-6, cytomegalovirus, and Japanese encephalitis virus showed no evidence of recent infection; PCR analysis of CSF was negative for Japanese encephalitis virus. Serology was negative for human immunodeficiency virus. The patient’s disturbed consciousness and pleocytosis resolved spontaneously within the next two months without steroid therapy, but he remained in a chronic disoriented state. Although his extremities were not paralyzed, pseudobulbar palsy and rigidity were evident at the chronic stage. MRI abnormalities improved gradually in parallel with the clinical improvement (Fig. 1B). Bilateral thalamic lesions are characteristic of some encephalopathies including Reye’s syndrome, Leigh’s encephalopathy, Wernicke’s encephalopathy, and acute necroLETTER TO THE EDITORS

Unilateral Saccadic Pursuit in Patients With Sensory Stroke Sign of a Pontine Tegmentum Lesion

BACKGROUND AND PURPOSE Pure hemisensory syndrome can be caused by small strokes occurring in a number of regions, including the thalamus and pons. Differentiation of the pontine sensory syndrome from the thalamic sensory syndrome has generally been made on the basis of distribution of sensory loss and involvement of specific sensory modalities but not without uncertainties and difficulties. Because the pontine tegmentum plays a pivotal role in generating horizontal eye movement, we attempted to discriminate these 2 syndromes by analyzing horizontal eye movements in stroke patients with pure hemisensory syndrome. METHODS Horizontal saccade, pursuit, vestibulo-ocular reflex (VOR), and VOR cancellation (VORC) were evaluated using electro-oculography in 6 patients with hemisensory syndromes, 3 due to pontine stroke and 3 due to thalamic stroke, and all were verified by MRI or CT. In addition, somatosensory evoked potentials (SEPs) were recorded. RESULTS Smooth pursuit and VORC directed toward the side of the lesion were impaired unilaterally in patients with pontine sensory stroke, whereas those 2 movements were intact bilaterally in patients with thalamic sensory stroke. Saccade and VOR were preserved in all patients. SEPs were normal in all patients with pontine and thalamic sensory strokes. No difference was found in the pattern of sensory disturbance between the 2 types of stroke patients. CONCLUSIONS Ipsilateral impairment of the smooth pursuit system may be a sign of a pontine lesion in patients with hemisensory stroke.

Conservative treatment of ruptured vertebrobasilar dissecting aneurysm

Ruptured vertebrobasilar dissecting aneurysm is usually treated surgically because rebleeding negatively affects outcome. However, the risk of rebleeding decreases markedly once several hours have passed from the initial bleeding. Moreover, surgery-related complications are not rare. We describe seven patients with ruptured vertebrobasilar dissecting aneurysm. To prevent rebleeding during the acute stage, we treated all seven patients conservatively with fentanyl instead of emergency surgery. During the follow-up period (mean 20 months), no patient suffered rebleeding. Conservative treatment with fentanyl administration may be a good option for management of ruptured vertebrobasilar dissecting aneurysm during the acute stage.

Encephalopathy in scleromyxedema

Article abstract The authors monitored CSF findings for over 5 months in a patient with a fatal case of scleromyxedema and two episodes of encephalopathy. During both encephalopathy episodes, CSF protein and immunoglobulin G (IgG) levels were elevated without an increased IgG index or IgG synthesis rate. A CSF-dominant increase in the concentration of interleukin-6 (IL-6) also was noted during encephalopathy. These findings suggest a disruption of the blood–brain barrier and that IL-6 may play some role in mediating the encephalopathy.

Wernicke's encephalopathy-like lesions in global cerebral hypoxia

We report a patient with severe hypoxic encephalopathy after cardiac arrest, in which lesions depicted on MRI involved mainly the periaqueductal brainstem, hypothalamus and mamillary bodies, and medial thalami. Hypoxia usually causes cerebro-cerebellar cortical damage. However, it may also cause midline lesions of similar distribution to those of Wernickes encephalopathy due to thiamine deficiency.

An unusual phenotype of McLeod syndrome with late onset axonal neuropathy

McLeod syndrome is a rare multisystem disorder defined by weak expression of the Kell glycoprotein antigens and the absence of a red blood cell surface antigen, Kx.1,2 The gene responsible for McLeod syndrome, XK , was cloned in 1994.1 The XK protein contains the Kx antigen missing in patients with McLeod syndrome. Mutation analysis of the XK gene has shown different deletions or point mutations in families with this condition.2,3 Clinical features of McLeod syndrome are reported to be heterogeneous.2,4,5 Clinical manifestations include acanthocytosis, an increased level of serum creatine kinase (CK), progressive muscular atrophy, seizures, and involuntary movement. As the symptoms and signs of this syndrome seem to be variable even among siblings, it is sometimes difficult to distinguish the condition from other neuromuscular disorders by clinical features and conventional examination. We report here two cases of McLeod syndrome in brothers and emphasise the variable features of the disease. Phenotypic variability was obvious in the two patients, and one case was unusual because the clinical features greatly resembled an axonal form of Charcot-Marie-Tooth disease. ### Case 1 A 50 year old man had been complaining of weakness and paraesthesiae in both legs. He first noted weakness in the right leg at the age of 37. Subsequently, the symptom extended to both legs, and he began to be unsteady on his …