Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of Henry G. Molaison, who underwent brain surgery for intractable epilepsy. The temporal association observed between the removal of his entorhinal cortex along with a significant part of hippocampus and the developing severe memory deficit inspired scientists to focus on these regions. The subsequent discovery of the so-called place cells in the hippocampus launched the description of many other functional cell types and neuronal networks throughout the Papez-circuit that has a key role in memory processes and spatial information coding (speed, head direction, border, grid, object-vector etc). Each of these cell types has its own unique characteristics, and together they form the so-called “Brain GPS”. The aim of this short survey is to highlight for practicing neurologists the types of cells and neuronal networks that represent the anatomical substrates and physiological correlates of pathological entities affecting the limbic system, especially in the temporal lobe. For that purpose, we survey early discoveries along with the most relevant neuroscience observations from the recent literature. By this brief survey, we highlight main cell types in the hippocampal formation, and describe their roles in spatial navigation and memory processes. In recent decades, an array of new and functionally unique neuron types has been recognized in the hippocampal formation, but likely more remain to be discovered. For a better understanding of the heterogeneous presentations of neurological disorders affecting this anatomical region, insights into the constantly evolving neuroscience behind may be helpful. The public health consequences of diseases that affect memory and spatial navigation are high, and grow as the population ages, prompting scientist to focus on further exploring this brain region.

We aimed to analyze the clinical, laboratory and neuroimaging findings in patients with sporadic Creutzfeldt-Jakob disease (CJD) in a single center as well as to review other published cases in Turkey. Between January 1st, 2014 and June 31st, 2017, all CJD cases were evaluated based on clinical findings, differential diagnosis, the previous misdiagnosis, electroencephalography (EEG), cerebrospinal fluid and cranial magnetic resonance imaging (MRI) findings in our center. All published cases in Turkey between 2005-2018 were also reviewed. In a total of 13 patients, progressive cognitive decline was the most common presenting symptom. Two patients had a diagnosis of Heidenhain variant, 1 patient had a diagnosis of Oppenheimer-Brownell variant. Seven patients (53.3%) had been misdiagnosed with depression, vascular dementia, normal pressure hydrocephalus or encephalitis. Eleven patients (87%) had typical MRI findings but only 5 of these were present at baseline. Asymmetrical high signal abnormalities on MRI were observed in 4 patients. Five patients (45.4%) had periodic spike wave complexes on EEG, all appeared during the follow-up. There were 74 published cases in Turkey bet­ween 2005 and 2018, with various clinical presentations. CJD has a variety of clinical features in our patient series as well as in cases reported in Turkey. Although progressive cognitive decline is the most common presenting symptom, unusual manifestations in early stages of the disease might cause misdiagnosis. Variant forms should be kept in mind in patients with isolated visual or cerebellar symptoms. MRI and EEG should be repeated during follow-up period if the clinical suspicion still exists.

CANOMAD (chronic ataxic neuropathy, ophthalmoplegia, M-protein agglutination, disialosyl antibodies) syndrome is a rare polyneuropathy. IgM paraproteins react with ganglioside-containing disialylated epitopes resulting in dorsal root ganglionopathy and B-lymphocyte infiltration of cranial and peripheral nerves. Clinical features include ataxia, slight muscle weakness, areflexia, sensory- and cranial nerve symptoms. Case studies have reported the efficacy of rituximab and intravenous immunoglobulin (IVIg) treatments. We present the case of a 57-year-old man, who had difficulty walking, with numbness and clumsiness in all limbs. He had areflexia, vibratory sensation loss and ataxia. Laboratory tests showed IgM monoclonal components and disialosyl antibodies in the serum. Nerve conduction studies indicated severe sensorimotor demyelinating polyneuroradiculopathy. Despite IVIg and rituximab treatments, the patient’s disease course gradually worsened and he died of respiratory failure. Neuropathological examination revealed dorsal column- and dorsal root atrophy with mixed mononuclear cell infiltration. This article aims to draw attention to this syndrome, and the use of early potent immunosuppressive treatment to improve patients’ quality of life.

The study aims to investigate the relationship between the progression of idiopathic Parkinson’s disease (IPD) and retinal morphology. The study was carried out with 23 patients diagnosed with early-stage IPD (phases 1 and 2 of the Hoehn and Yahr scale) and 30 age-matched healthy controls. All patients were followed up at least two years, with 6-month intervals (initial, 6th month, 12th month, 18th month, and 24th month), and detailed neurological and ophthalmic examinations were performed at each follow-up. Unified Parkinson’s Disease Rating Scale part III (UPDRS Part III) scores, Hoehn and Yahr (H&Y) scores, best-corrected visual acuity (BCVA), intraocular pressure (IOP) measurement, central macular thickness (CMT) and retinal nerve fiber layer (RNFL) thickness were analyzed at each visit. The average age of the IPD and control groups was 43.96 ± 4.88 years, 44.53 ± 0.83 years, respectively. The mean duration of the disease in the IPD group was 7.48 ± 5.10 months at the start of the study (range 0-16). There was no statistically significant difference in BCVA and IOP values between the two groups during the two-year follow-up period (p> 0.05, p> 0.05, respectively). Average and superior quadrant RNFL thicknesses were statistically different between the two groups at 24 months and there was no significant difference between other visits (p=0.025, p=0.034, p> 0.05, respectively). There was no statistically significant difference in CMT between the two groups during the follow-up period (p> 0.05). Average and superior quadrant RNFL thicknesses were significantly thinning with the progression of IPD.

[The carpal tunnel syndrome is the most frequent compression-induced neuropathy. A severe but rare clinical manifestation of this disorder associates with ulceration, acral osteo-lysis and mutilation of the terminal phalanges of the second and third fingers. Recognition of this disorder is difficult, because various dermatological and internal diseases might lead to acral ulcerative lesions, and these patients are seldom referred to neurological and/or electrodiagnostic examination. In this article, we present three cases of this rare clinical form of carpal tunnel syndrome and discuss the electrodiagnostic findings. The early diagnosis is important since decompression of the median nerve in due time might prevent mutilation and could significantly improve the patients’ quality of life.]