RESIDENT & FELLOW SECTION Pearls & Oy-sters: Section Editor A rare case of neurotrichinosis with MRI Mitchell S.V. Elkind, MD, MS Christine M. McDonald, PEARLS and sensory examination. Strength in the left upper MD 1. The neurologic manifestations of trichinosis are extremity was decreased to 4/5 in all muscle groups. Peter Tai, MD, FRCPC, diverse and range from encephalopathy to cere- The remainder of the strength examination was nor- ABPN bral, cerebellar, and spinal cord abnormalities. mal. Reflexes were present and symmetric. There was Timo Krings, MD, PhD, 2. MRI lesions enhance with contrast and are postu- a left-sided pronator drift, slowing of finger-to-nose FRCPC(C) lated to represent small areas of infarction. testing, and inability to perform rapid alternating 3. Imaging typically normalizes within 1 to 2 months movements with the left arm. Gait was unstable, after infection. and the patient used a wheelchair to mobilize in the Correspondence to hospital. Dr. McDonald: [email protected] Laboratory tests were remarkable for a leukocyte OY-STERS count of 15.3 3 109/L, an eosinophil count of 1. Neurotrichinosis should be considered in patients 5.8 3 109/L (38%), platelets of 147 3 109/L, crea- with marked eosinophilia and unexplained neuro- tine kinase of 290 U/L, troponin of 3.12 mg/L, and logic symptoms. erythrocyte sedimentation rate of 34 mm/h. There 2. Outcomes may be improved with the administra- was no evidence of ST elevation on ECG, and chest tion of steroids and anthelmintic agents during the x-ray was normal. CSF analysis showed glucose enteral phase of infection. of 57.6 mg/dL, protein 34 mg/dL, erythrocytes 9.5/mm3, leukocytes 3.6/mm3, and a negative Gram CASE REPORT A 41-year-old left-handed man from stain and culture. There were too few leukocytes in a northern Canadian district presented to a the CSF to provide a differential. Blood cultures, stool community hospital with a 3-week history of watery culture, and stool for ova and parasites were all negative. diarrhea, a self-resolved erythematous pruritic rash, Rheumatologic markers were negative. Echocardiogram fever, confusion, and facial swelling. A CT scan of showed normal ventricular and valvular function. An the head showed areas of decreased attenuation EEG showed slow-wave activity in the left temporal bilaterally in the periventricular regions of the region. There was no epileptiform activity. frontal lobes. He was offered admission for workup Brain MRI (figure) demonstrated multiple bilateral but declined and was sent home with antibiotics. areas of increased signal intensity in both the deep white He returned to the hospital 3 days later with new matter and gray–white matter interface of the frontal complaints of left face numbness as well as left arm and parietal lobes bilaterally, with very few lesions seen numbness, weakness, and clumsiness. His partner in the occipital and temporal lobes and the cerebellum noted that he was sleeping more than usual and had on T2 fluid-attenuated inversion recovery (FLAIR) and word-finding difficulties. Other symptoms included T2-weighted scans. Diffusion-weighted scans demon- daily bifrontal headache, “red spots” briefly strated restriction in some of the deep white matter appearing in his visual field, and ataxia. lesions, indicating ischemia. Lesions were slightly hypo- Medical history was significant for vasectomy, intense on unenhanced T1 images and there was no 20-pack-year smoking history, and headaches. He pathologic blooming artifact on T2 gradient echo had no allergies and no regular medications. sequences that would have suggested blood products. On admission, vital signs were within normal lim- Following contrast administration, there was an intense its, and there was no documented fever. Cardiorespi- rim of enhancement in most lesions. The area of ratory and abdominal examination results were enhancement was smaller than 4 mm in all lesions, with normal. There was no facial edema or skin lesions. the T2 and FLAIR signal abnormality surrounding the Cognition was intact. He had a normal cranial nerve lesions measuring up to 8 mm. From the Department of Medicine (C.M.M.), Mount Sinai Hospital, Toronto; Department of Medicine (P.T.) and Neuroradiology (T.K.), University of Toronto (C.M.M.); and the Toronto Western Hospital & University Health Network (P.T., T.K.), Canada. Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article. e30 © 2014 American Academy of Neurology Figure Multimodal MRI of Trichinella infection involving the brain Multimodal MRI including T2 fluid-attenuated inversion recovery (FLAIR)–weighted sequences (A), T2 turbo spin-echo se- quences (B), T2 gradient echo sequences (C), and diffusion-weighted imaging scans (D), as well as contrast-enhanced T1- weighted sequences (E–H), demonstrate multiple disperse, nonconfluent foci of T2 and FLAIR hyperintensity in the deep white matter (arrows). There is no abnormal blooming on T2 gradient echo sequences, but restricted diffusion is seen in some of the lesions. Contrast enhancement is visualized in both the deep white matter and multiple cortical/subcortical regions. Images were obtained at approximately 7 weeks in the patient’s disease course. The patient was transferred to our center approx- gastric acid in the stomach, and invade the small intes- imately 7 weeks into his disease course for further tinal mucosa. The larvae mature and reproduce, releas- neurologic opinion. He complained of persistent ing newborn larvae into intestinal lymphatics 7 to 10 headache, myalgias, and difficulty with concentra- days after ingestion. The parenteral phase commences tion. A dietary history was elicited, and the patient re- with hematogenous spread of larvae to various tissues, ported consuming undercooked black bear meat over including striated muscle. The larvae encyst in muscle the preceding 3 months. He was an avid hunter. tissue and can remain viable for months to years.2 Trichinella serology by complement fixation was reac- Patients with trichinosis may present with diarrhea, tive with a titer of 1:16. The patient was diagnosed fever, periorbital edema, weakness, rash, and myalgias.3 with trichinosis complicated by myocarditis and CNS Bloodwork shows marked eosinophilia. Trichinella involvement. He was comanaged with an infectious infection of the CNS, referred to as neurotrichinosis, disease consultant, and, taking into consideration the occurs in as few as 0.2% but as many as 52% of cases improvement of CNS symptoms, stability of MRI and represents serious infection.4 Neurologic signs and findings, and late stage in the course of infection, symptoms are nonspecific and range from encephalo- steroids and anthelmintics were not prescribed. He pathy to hemiparesis and ataxia. For this reason, neuro- was discharged with follow-up, and the local public trichinosis is clinically underrecognized.5 Cases health agency was involved for contact tracing. associated with outbreaks are identified more readily as compared to sporadic infections.6 DISCUSSION Trichinosis is a parasitic infection CNS injury is through both direct and indirect caused by nematodes of the genus Trichinella, with mechanisms. Larvae migrate to the brain and cause transmission occurring through ingestion of under- local destruction, obstruct vasculature, and provoke cooked infected meat. The primary reservoir is pigs, an inflammatory response.7 There is no predilection although transmission through game (e.g., wild boar, for specific areas of the CNS.4 Vascular changes, bear, walrus) is also reported. The parasite is found primarily microinfarctions, are thought to be most worldwide, and 66 cases of human infection were responsible for neurologic injury and may be medi- reported in the United States between 2002 and ated by the hypereosinophilic state.5,6 2007.1 The Trichinella life cycle involves an enteral In previous reports, CT imaging of the brain and a parenteral phase. During the enteral phase, revealed multifocal hypodensities in the cerebral encysted larvae are ingested by the host, released by cortex and white matter.5,6 The MRI appearance of Neurology 82 January 28, 2014 e31 neurotrichinosis is less frequently described in the lit- some patients have chronic sequelae. Mortality is as erature. Lesions appear hyperintense on T2-weighted high as 5% when the CNS is involved.2 For this rea- images, enhance with gadolinium, and show restricted son, patients with neurotrichinosis should be hospital- diffusion on diffusion-weighted imaging.8 Imaging ized for observation and investigated for multisystem findings correlate with pathologic findings of cortical involvement. Our patient made a near-full neurologic and white matter microinfarctions.6 Findings on imag- recovery in 2 months, with his primary residual deficits ing typically improve within 1 to 2 months of infec- being a very mild encephalopathy and headache. tion.4 The CT and MRI findings in our case were consistent with what has been previously described AUTHOR CONTRIBUTIONS and were suggestive of ischemic injuries of varying Dr. McDonald participated in patient care and wrote and revised the manuscript. Dr. Tai participated in patient care and provided revisions ages. MRI findings of neurotrichinosis are nonspecific to the manuscript. Dr. Krings provided MRI interpretation, the figure, but argue against alternate diagnoses in our case: the and revisions to the manuscript. absence of significant edema surrounding the lesions is inconsistent with septic emboli or metastases; the dense STUDY FUNDING enhancement of lesions over a long period of time is No targeted funding reported. inconsistent with ischemic embolic lesions; the absence of abnormal blooming on T2 gradient echo sequences DISCLOSURE speaks against mycotic aneurysms; and the absence of C. McDonald reports no disclosures. P. Tai is a staff neurologist at Uni- versity Health Network in Toronto and has received funding as a site leptomeningeal enhancement is inconsistent with investigator from Upsher-Smith Laboratories in an unrelated randomized sarcoidosis or other granulomatous disease.