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Temporal Lobe Neurological Disorders

by Patrick di Santo 3 months ago in mental health

brain

all rights reserved IDP, University of Kansas, 2021

Memory disruption is a major complicating feature of disease entities causing temporal lobe involvement: infectious, metabolic, neoplastic, degenerative aetiologies, trauma, and cerebrovascular events all play a role. One of the most common temporal lobe disease(s) is epilepsy, along with cognitive impairment. The problem of memory impairment in temporal lobe epilepsy or TLE. Anatomical abnormalities include alztimers and often extend far outside the temporal lobe, as well as extend beyond memory function, and cognitive impairments. There appear(s) to be a connection between cognitive and anatomical abnormalities, one must understand the anatomical architecture of cognitive impairment and how it relates to epilepsy. Some improvement has been made through anterior temporal lobectomy, with efforts made to predict which subject(s) are at risk of adverse cognitive outcomes from the disorder. Surgery on the lobe is also considered a remedy for some candidate(s). Often hippocampus integrity is the deciding factor.

Infectious Diseases

Most common and gravest form of acute encephalitis is Herpes encephalitis, almost always caused by latent Herpes Simplex Virus-1 or HSV-1. The virus spreads retrograde from the trigeminal ganglion and along trigeminal nerve fibre(s) presenting acute fever(s), headache(s), seizure(s) and altered mental status [1]Human herpesvirus 6 or HHV-6) a neurotrophic virus that cause(s) roseola infantum and exanthem subitum in childhood. 90 % of the population by the age of 2 years test positive to the virus though remain asymptomatic [2]. Reactivate can cause encephalopathy in immunocompromised subject(s), appears most often in organ transplantation subject(s),presents as a change in mental status, loss of short-term memory and seizures.

Mucormycosis is a fungal infection that often spreads through the maxillary and ethmoid sinuses to the temporal lobes in immunocompromised subjects. Diffuse cerebral parenchymal type, brain oedema, haemorrhages and irregular enhancement (Fig. 3) [3]. Again in those with immune deficiency or paranasal sinuses infection.

Infection to the temporal lobe may also occur from otomastoiditis, syphilis and flavivirus all can affect the temporal lobe [4]

Inflammation

Paraneoplastic limbic encephalitis an immune-mediated encephalitis, antigen response shared by a neoplasm in the nervous system [5]. Presentation subacute with personality changes, irritability, depression, dementia, seizures and short-term memory loss. This disorder is associated with small cell lung carcinoma and testicular germ cell tumour(s).

Neurodegenerative Diseases

Most common type of dementia is alzheimer(s), which present(s) as severe cognitive impairment. Bi-temporal involvement is a known a feature (Fig. 6), indicated by loss of volume in the mesial temporal structures, especially the entorhinal cortex [6] is the second most common type of dementia, a heterogeneous group of disorders with preferential temporal and atrophy [7].

Metabolic Diseases

Adult onset ornithine transcarbamylase or OTC a milder form of the x-linked disease, present(s) with signs of encephalopathy with increased vulnerability to hyperammonemic hyper glutaminergic status [8].

Epileptogenic Syndrome

Mesial temporal sclerosis is one of the most common pathological substrate(s) for complex seizures associated with epilepsy [9].

Neoplasm

Spread from one temporal lobe to another, consisting of white matter tracts interconnecting the temporal lobes. This pattern is often seen in glial cell tumours, diffuse astrocytoma, anaplastic astrocytoma and glioblastoma multiforme [10].

Cerebrovascular Disease

The medial aspect of both temporal lobes, basilar tip and bilateral PCA occlusion causing ischemic injury. Subject(s) present acutely with visual, memory deficits, and altered mental status. Brainstem, cerebellar, and thalamic dysfunction can be present [11].

References

[1] Noguchi T, Yoshiura T, Hiwatashi A, Togao O, Yamashita K, Nagao E et al (2010) CT and MRI findings of human herpesvirus 6–associated encephalopathy: comparison with findings of herpes simplex virus encephalitis. AJR.

[2] Sauerbrei A, et al. (2000) Virological diagnosis of herpes simplex encephalitis. J Clin Virol.

[3] Jain KK, Mittal SK, Kumar S, Gupta RK (2007) Imaging features of central nervous system fungal infections. Neurol India.

[4] Russo A, Farina E, Nicoletti L, Nemni R (2009) Selective involvement of temporal regions in a case of flavivirus encephalitis. Neurol Sci.

[5] Mamata H, Mamata Y, Westin CF, Shenton ME, Kikinis R, Jolesz FA et al (2002) High-resolution line scan diffusion tensor MR imaging of white matter fiber tract anatomy. AJNR Am J Neuroradiol.

[6] Gultekin SH, Rosenfeld MR, Voltz R, Eichen J, Posner JB, Dalmau J (2000) Paraneoplastic limbic encephalitis: neurological symptoms, immunological findings and tumour association.

[7] Perry RJ, Hodges JR (2000) Differentiating frontal and temporal variant frontotemporal dementia from Alzheimer’s disease. Neurology

[8] Gadian DG, Aicardi J, Watkins KE, Porter DA, Mishkin M, Vargha-Khadem F (2000) Developmental amnesia associated with early hypoxic–ischaemic injury. Brain.

[9] Urbach H (2005) Imaging of the epilepsies. Eur Radiol.

[10] Singhal S, Rich P, Markus HS (2005) The spatial distribution of MR imaging abnormalities in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy and their relationship to age and clinical features. AJNR Am J Neuroradiol.

[11] Miaux Y, Chiras J, Eymard B, Lauriot-Prevost MC, Radvanyi H, Martin-Duverneuil N et al (1997) Cranial MRI findings in myotonic dystrophy. Neuroradiology.

Larger and more developed in humans than in any other organism, the frontal lobe as its name indicates, is the anterior frontal of one's face behind their forehead.The left hemisphere of this lobe controls the right side of the body, below the head and vice versa. Controlling cognitive skills important to emotional expression, problem solving, memory, language, judgment, and sexual behaviors. Containing four main gyri.

Directly anterior to the central sulcus and running parallel to it, is the primary motor cortex (Brodmann area 4) and known as the precentral gyrus, the motor cortex, most responsible for voluntary movements of the body.

The motor homunculus, pairs specific regions of the motor cortex with the extremity it controls. The medial portion of the homunculus control(s) the lower part of one's anatomy, while the intermediate portion, the upper part of one's anatomy[1], the lateral is responsible for facial muscles.

The corticospinal tract is the pathway by which extremities are controlled including voluntary facial movement.

The precentral gyrus, anterior to the motor cortex, is the prefrontal cortex. Responsible for complex order association and is centered in the organ: interpret(s) decision making, reasoning, personality expression, maintaining social appropriateness, higher cognitive behavior(s)[2].

Running parallel and rostral to the precentral gyrus is the central sulcus which extends forward and downward from the precentral sulcus.

The superior and inferior frontal sulcus divide this lobe's surface laterally and into the remaining three main gyri: inferior, middle and superior frontal gyri.[3] The functions of these three gyri are the topic of much research currently. The dominant superior (L) frontal gyrus processes working memory in the neural network and spatial processing.[4] The nondominant (R) superior frontal gyrus processes impulse(s), inhibition, and urgency.

Separated from it by the superior frontal sulcus, is the middle frontal gyrus is dominant (L) middle frontal gyrus which encourages literacy growth[5]. The middle frontal gyrus is the nondominant (R) responsible for numeric processes,[6] the middle frontal gyrus, is home to the caudal portion, intersecting the precentral gyrus (Brodmann area 8) the frontal eye fields controlling saccadic eye movements, rapid, and conjugate eye movements that allow the central vision to understand detail.[7]

The inferior frontal gyrus is the lowest gyrus of the frontal lobe, separated from the middle frontal gyrus by the inferior frontal sulcus. The caudal portion of the dominant (L) inferior frontal gyrus contains Broca's area (Brodmann area 44 and 45), which is responsible for speech production[8].

References

[1] Seladi-Schulman, Jill. (2020) What to Know About Your Brain’s Frontal Lobe, Healthline

[2] Stiles J, Jernigan TL. (2010) The basics of brain development. Neuropsychol Rev.

[3] Bui T, M Das J. StatPearls (2020). StatPearls Publishing

[4] du Boisgueheneuc F, Levy R, Volle E, Seassau M, Duffau H, Kinkingnehun S, Samson Y, Zhang S, Dubois B. (2006) Functions of the left superior frontal gyrus in humans: a lesion study. Brain.

[5] Hu S, Ide JS, Zhang S, Li CR. (2016) The Right Superior Frontal Gyrus and Individual Variation in Proactive Control of Impulsive Response. J Neurosci.

[6] Koyama MS, O'Connor D, Shehzad Z, Milham MP. (2017) Differential contributions of the middle frontal gyrus functional connectivity to literacy and numeracy. Sci Rep

[7] Termsarasab P, Thammongkolchai T, Rucker JC, Frucht SJ. (2015) The diagnostic value of saccades in movement disorder patients: a practical guide and review.

[8] Stinnett TJ, Reddy V, Zabel MK. (2020) StatPearls [Internet]. StatPearls Publishing

mental health

Patrick di Santo

Research Scientist affiliated with the University of Kansas

and The Union Center for Cultural and Environmental Research

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