Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication
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The most common cause of eosinophilic meningitis is the invasion of the central nervous system by helminthic parasites, in particular Angiostrongylus cantonensis—also known as the rat lung worm.1 This parasitic infection is more common in South East Asia and Pacific regions,1,2 but sporadic cases have been reported in many regions.3–5 Humans can acquire the infection by eating raw or undercooked snails or slugs infected with the parasite. The major intermediate hosts in Taiwan are the African giant snail (Achatina fulica) (fig 1) and the golden apple snail (Ampullarium canalicullatus).6 Helminthic parasites, in particular A cantonensis, are seen in all regions in Taiwan and are an important cause of eosinophilic meningitis. The cases reported in Taiwan have almost all occurred among children. In addition, most of the cases were recorded before the 1970s.6
Our patient is a mentally challenged 21-year-old Taiwanese man who presented with intermittent bilateral lower extremity weakness, fever, headache and acute urinary retention, and was finally diagnosed with eosinophilic meningitis due to A cantonensis. Acute urinary retention with aseptic meningitis, which was seen in our patient, is an unusual manifestation.7 Presence of acute urinary retention with cerebrospinal fluid (CSF) pleocytosis, and variable spinal cord dysfunction, is known as Elsberg syndrome.7–10 After the affiliated medical treatment and rehabilitation intervention for bladder training and bilateral lower leg function training, his daily life function improved effectively.
The patient, a 25-year-old Taiwanese man residing in Pingtung County, South Taiwan, appeared well before hospital admission. His occupation was a weeder in the nuclear power plant of Taiwan Power Company. He had some minimal mental disability following an unknown childhood infection. He presented with intermittent bilateral lower limb weakness, painful sensation in both lower limbs, and dysesthesia of the feet, and had a low grade fever (37.6°C) since November 2005. Initially, he was sent to the local hospital for treatment. Because his symptoms and signs were persistent and his consciousness became disturbed, he was transferred to Chung-Ho Memorial Hospital, Kaohsiung Medical University, Taiwan, on the third day of his illness. In the emergency department, hyponatraemia (127 mol/l) and mild leucocytosis (white blood cells (WBC) 10430/μl) with acute urine retention were found. Mild drowsiness, disorientation, headache and moderate neck stiffness were present, while Kerning’s sign and Brudzinski sign were positive. Cranial nerves were normal. Motor power was decreased with 5/5 power in upper limbs and 4/5 in lower limbs, and areflexia of bilateral knee and ankle jerk and absent bilateral plantar responses were noted. Sensation to pinprick or light touch were symmetrical. The patient was admitted for evaluation and treatment.
Routine blood analysis showed that the leucocyte count was 11550/μl with 70% polymorphonuclear cells, 10% lymphocytes, 9% monocytes, and 11% eosinophils at admission. Renal and liver function tests were normal. Due to persistent fever and a gradually worsening mental status with visual hallucination, a lumbar puncture was performed on day 3 after admission (table 1). Opening pressure of 40 cm H2O was noted; CSF appeared cloudy with 198 WBCs (59% eosinophils), a CSF protein value of 163 mg/dl, and a CSF glucose value of 36 mg/dl.
With worsening mental status and fever, brain magnetic resonance imaging (MRI) was arranged, the findings from which were unremarkable. Due to the above condition, a second lumbar puncture was performed on day 5 after admission (table 1) and the results demonstrated an opening pressure of 90 cm H2O, 1584 WBCs (76% eosinophils), a CSF protein value of 127 mg/dl, and a CSF glucose value of 26 mg/dl. CSF culture for bacteria yielded no growth. In addition, elevated angiostrongyliasis titre in the CSF and serum was found later.
Abdominal ultrasound showed acute renal parenchymal disease. Urodynamic studies revealed normal detrusor power with poor detrusor contractility sustained, abdominal strain during voiding, and poor sphincter relaxation during voiding (fig 2). Nerve conduction study revealed normal status except absent H reflex and multiple roots lesion within proximal parts were suspected. On reviewing the history in detail, no significant past medical, family, or travel history was noted. However, the patient had eaten undercooked raw snail identified by photography (fig 1) before this episode.
After diagnosis of eosinophilic meningitis, mebendazole at a dose of 100 mg twice daily for 5 days and oral glucocorticosteroid at a dose of 60 mg/day for 5 days was prescribed for treatment of the infection and relief of symptoms. After supportive care and medication treatment, his consciousness improved while headache and fever subsided gradually. Bladder dysfunction was still noted, requiring placement of an indwelling urinary catheter. The patient was then transferred to the rehabilitation ward for training. The rehabilitation included walking, muscle strengthening and endurance training of bilateral lower legs, gait pattern correction, balance and coordination. Initially, he could walk with a walker for several metres and then ambulate without this device after 1 month of rehabilitation training. His condition improved gradually and the indwelling catheter was subsequently removed. He has attended regular outpatient department follow-up and his general health has improved.
Tumour, spinal cord infarction, necrosis, vasculitis, drug induced or other source of infection.
The treatment of eosinophilic meningitis caused by A cantonensis with an anthelminthic agent is still equivocal due to its efficacy and the allergic adverse effect of the antigens released by dying worms. The anthelminthic agents included thiabendazole, albendazole, mebendazole and ivermectin, but the results were inconclusive. Treatment consists of supportive care with corticosteroids for decreasing inflammation in the central nervous system.
OUTCOME AND FOLLOW-UP
The prognosis of eosinophilic meningitis is good, but fatal outcomes have been described. The clinical course is usually self limited with symptoms resolving in 1–5 weeks. Significant improvement is usually noted within 1–2 months. Facial paralysis is the most persistent symptom. Prolonged headache or paresthesia may persist for several months and fatal outcomes have been described.4 Prognosis for acute urine retention is also good.
A cantonensis, a natural parasite of rats, is the most common cause of eosinophilic meningitis and was first described in 1935 by Chen et al in Guangzhou, Guangdong Province, China.6 The first report of human infection was confirmed in Tainan, Taiwan in 1945.11 The infection is via ingesting third stage larvae in raw intermediate hosts or paratenic hosts.12 Only a few cases of eosinophilic meningitis have been reported in the most recent three decades.13,14
Eosinophilic meningitis is defined by the presence of 10 or more eosinophils per μl in the CSF or eosinophilia of at least 10% of the total CSF leucocyte count. Making a definitive diagnosis of eosinophilic meningitis due to A cantonensis is difficult. Such diagnosis of angiostrongyliasis is usually by clinical diagnosis. Patients with a history of exposure in an area of endemicity, with compatible symptoms and signs and CSF eosinophilia, should be considered for the diagnosis.15 Determining consumption of a raw snail by the patient is critical to the diagnosis.16 The imaging characteristics of eosinophilic myelomeningoencephalitis are various. The main MRI findings are multiple nodular enhancing lesions in the brain and linear enhancement in the pia, with stick-like enhancement being a characteristic sign of the disease.11 In addition, the timing of the observation of dynamic changes of the disorders in the central nervous system, based on follow-up MRI examinations, suggested that the lesions are more severe in the fifth to eighth week after the onset of symptoms, while new lesions could still occur after the eighth week.11 Due to the above reason, MRI study was always normal initially, as in our patient. The case we present became infected by eating the raw African giant snail (fig 1).
Headache is the most common symptom. In addition, fever, delirium, seizures, impaired cognitive function, neck stiffness, vomiting, and general weakness have also been reported.15 The most distinctive neurological finding in humans with angiostrongyliasis is paresthesia.15 The patient had headache, painful sensation of bilateral low limbs, paresthesia, fever, weakness and delirium, which are all compatible with distinctive finding. The severity of this patient’s condition is mostly likely to be a function of increased worm burden as indicated by the abundant eosinophils in the CSF (table 1). However, our patient had acute urinary retention initially without urologic abnormalities such as prostatic hypertrophy. Acute urinary retention with aseptic meningitis is an unusual manifestation.7 Acute urinary retention as a syndrome with CSF pleocytosis and variable spinal cord dysfunction was first described in 1931 and is known as Elsberg syndrome after the discoverer.7–10 It is a urological emergency and the differential diagnosis of acute urinary retention includes psychogenic urinary retention, the first manifestation of multiple sclerosis, drug intoxication, lumbosacral disc protrusion, and rheumatological disorders.7
Due to the onset of urinary retention followed by other meningitis symptoms such as altered consciousness, neck stiffness, headache and fever, Elsberg syndrome caused by eosinophilic meningitis was suspected in our patient. Elsberg syndrome caused by genital herpes, especially herpes simplex virus type 2 (HSV 2), is the most common type reported.10 Other aetiologies such as HSV1, human herpes virus, varicella zoster virus, Epstein–Barr virus,17 and ECHO virus18 have also been reported. Although urinary retention accompanying eosinophilic meningitis caused by A cantonensis has been reported in a few paediatric cases,19 only one adult with urinary retention considered to be caused by A cantonensis has been reported (by Furugen et al in 20069), but bilateral leg weakness had not been described.
Nerve conduction study revealed normal status except absent H reflex and multiple roots lesion within proximal parts were suspected. Clinically, H reflex is most helpful for surveying for polyneuropathy or confirming sciatic neuropathy. It is important to remember that delay in the H reflex can occur with lesions of the sciatic nerve, the lumbosacral plexus, or the S1 root. A urodynamic study was arranged after transferral to the rehabilitation ward, and normal detrusor power with poor detrusor contractility sustained, abdominal strain during voiding, and poor sphincter relaxation during voiding was noted (fig 1). Due to the above reasons, we educated the patient about clean intermittent catheterisation (CIC) and his neurogenic bladder improved later.
In the present case, his unstable gait lasted for 3 months after his illness began and recovery in his bilateral lower legs is less than in the upper extremities. He could ambulate with an unstable gait using a walker for a few metres initially. His symptoms, especially limbs weakness, are more prolonged than predicted and we suspect complications via eosinophilic meningitis. Lumbar spine MRI was arranged and mild herniated intervertebral disc (HIVD) of L4–5, L5–S1 was noted. Abnormal enhancement of the dura was also noted (fig 3). This finding on MRI and nerve conduction study may explain the reason why recovery in the bilateral lower legs was poorer than in the upper limbs. Rather than implementing the traditional rehabilitation for lumbar HIVD, with hot pack and lumbar traction, we focused on walking, muscle strengthening and endurance training of the bilateral lower legs, gait pattern correction, balance and coordination, and adjusted this protocol according to the patient’s condition. After training, his muscle power improved, he could ambulate without a device, and was able to take care of himself 1 month later.
Only a few cases of eosinophilic meningitis have been reported in the pass three decades. A literature review revealed very few articles describing the use of rehabilitation applied to the patient with eosinophilic meningitis. In addition, Elsberg syndrome caused by eosinophilic meningitis is rarely seen. Although the clinical course is usually self limited, some patients take a longer time to achieve a healthy recovery before rehabilitation programme intervention.
Infection secondary to A cantonensis should be considered in patients diagnosed with aseptic meningitis and a history of contact with snails.
In patients with aseptic meningitis combined with urologic dysfunction and spinal cord dysfunction, Elsberg syndrome should be considered.
The use of MRI is important for achieving an early diagnosis of the disease.
Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication
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